Search Results

Search found 44207 results on 1769 pages for 'java interface'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 755/1769 | < Previous Page | 751 752 753 754 755 756 757 758 759 760 761 762  | Next Page >

  • Java or C for image processing

    - by its-me
    I am looking in to learning a programming language (take a course) for image analysis and processing. Possibly Bioinformatics too. Which language should I go for? C or Java? Other languages are not an option for me. Also please explain why either of the languages is a better option for my application.

    Read the article

  • Syncing Data with a Server using Silverlight and HTTP Polling Duplex

    - by dwahlin
    Many applications have the need to stay in-sync with data provided by a service. Although web applications typically rely on standard polling techniques to check if data has changed, Silverlight provides several interesting options for keeping an application in-sync that rely on server “push” technologies. A few years back I wrote several blog posts covering different “push” technologies available in Silverlight that rely on sockets or HTTP Polling Duplex. We recently had a project that looked like it could benefit from pushing data from a server to one or more clients so I thought I’d revisit the subject and provide some updates to the original code posted. If you’ve worked with AJAX before in Web applications then you know that until browsers fully support web sockets or other duplex (bi-directional communication) technologies that it’s difficult to keep applications in-sync with a server without relying on polling. The problem with polling is that you have to check for changes on the server on a timed-basis which can often be wasteful and take up unnecessary resources. With server “push” technologies, data can be pushed from the server to the client as it changes. Once the data is received, the client can update the user interface as appropriate. Using “push” technologies allows the client to listen for changes from the data but stay 100% focused on client activities as opposed to worrying about polling and asking the server if anything has changed. Silverlight provides several options for pushing data from a server to a client including sockets, TCP bindings and HTTP Polling Duplex.  Each has its own strengths and weaknesses as far as performance and setup work with HTTP Polling Duplex arguably being the easiest to setup and get going.  In this article I’ll demonstrate how HTTP Polling Duplex can be used in Silverlight 4 applications to push data and show how you can create a WCF server that provides an HTTP Polling Duplex binding that a Silverlight client can consume.   What is HTTP Polling Duplex? Technologies that allow data to be pushed from a server to a client rely on duplex functionality. Duplex (or bi-directional) communication allows data to be passed in both directions.  A client can call a service and the server can call the client. HTTP Polling Duplex (as its name implies) allows a server to communicate with a client without forcing the client to constantly poll the server. It has the benefit of being able to run on port 80 making setup a breeze compared to the other options which require specific ports to be used and cross-domain policy files to be exposed on port 943 (as with sockets and TCP bindings). Having said that, if you’re looking for the best speed possible then sockets and TCP bindings are the way to go. But, they’re not the only game in town when it comes to duplex communication. The first time I heard about HTTP Polling Duplex (initially available in Silverlight 2) I wasn’t exactly sure how it was any better than standard polling used in AJAX applications. I read the Silverlight SDK, looked at various resources and generally found the following definition unhelpful as far as understanding the actual benefits that HTTP Polling Duplex provided: "The Silverlight client periodically polls the service on the network layer, and checks for any new messages that the service wants to send on the callback channel. The service queues all messages sent on the client callback channel and delivers them to the client when the client polls the service." Although the previous definition explained the overall process, it sounded as if standard polling was used. Fortunately, Microsoft’s Scott Guthrie provided me with a more clear definition several years back that explains the benefits provided by HTTP Polling Duplex quite well (used with his permission): "The [HTTP Polling Duplex] duplex support does use polling in the background to implement notifications – although the way it does it is different than manual polling. It initiates a network request, and then the request is effectively “put to sleep” waiting for the server to respond (it doesn’t come back immediately). The server then keeps the connection open but not active until it has something to send back (or the connection times out after 90 seconds – at which point the duplex client will connect again and wait). This way you are avoiding hitting the server repeatedly – but still get an immediate response when there is data to send." After hearing Scott’s definition the light bulb went on and it all made sense. A client makes a request to a server to check for changes, but instead of the request returning immediately, it parks itself on the server and waits for data. It’s kind of like waiting to pick up a pizza at the store. Instead of calling the store over and over to check the status, you sit in the store and wait until the pizza (the request data) is ready. Once it’s ready you take it back home (to the client). This technique provides a lot of efficiency gains over standard polling techniques even though it does use some polling of its own as a request is initially made from a client to a server. So how do you implement HTTP Polling Duplex in your Silverlight applications? Let’s take a look at the process by starting with the server. Creating an HTTP Polling Duplex WCF Service Creating a WCF service that exposes an HTTP Polling Duplex binding is straightforward as far as coding goes. Add some one way operations into an interface, create a client callback interface and you’re ready to go. The most challenging part comes into play when configuring the service to properly support the necessary binding and that’s more of a cut and paste operation once you know the configuration code to use. To create an HTTP Polling Duplex service you’ll need to expose server-side and client-side interfaces and reference the System.ServiceModel.PollingDuplex assembly (located at C:\Program Files (x86)\Microsoft SDKs\Silverlight\v4.0\Libraries\Server on my machine) in the server project. For the demo application I upgraded a basketball simulation service to support the latest polling duplex assemblies. The service simulates a simple basketball game using a Game class and pushes information about the game such as score, fouls, shots and more to the client as the game changes over time. Before jumping too far into the game push service, it’s important to discuss two interfaces used by the service to communicate in a bi-directional manner. The first is called IGameStreamService and defines the methods/operations that the client can call on the server (see Listing 1). The second is IGameStreamClient which defines the callback methods that a server can use to communicate with a client (see Listing 2).   [ServiceContract(Namespace = "Silverlight", CallbackContract = typeof(IGameStreamClient))] public interface IGameStreamService { [OperationContract(IsOneWay = true)] void GetTeamData(); } Listing 1. The IGameStreamService interface defines server operations that can be called on the server.   [ServiceContract] public interface IGameStreamClient { [OperationContract(IsOneWay = true)] void ReceiveTeamData(List<Team> teamData); [OperationContract(IsOneWay = true, AsyncPattern=true)] IAsyncResult BeginReceiveGameData(GameData gameData, AsyncCallback callback, object state); void EndReceiveGameData(IAsyncResult result); } Listing 2. The IGameStreamClient interfaces defines client operations that a server can call.   The IGameStreamService interface is decorated with the standard ServiceContract attribute but also contains a value for the CallbackContract property.  This property is used to define the interface that the client will expose (IGameStreamClient in this example) and use to receive data pushed from the service. Notice that each OperationContract attribute in both interfaces sets the IsOneWay property to true. This means that the operation can be called and passed data as appropriate, however, no data will be passed back. Instead, data will be pushed back to the client as it’s available.  Looking through the IGameStreamService interface you can see that the client can request team data whereas the IGameStreamClient interface allows team and game data to be received by the client. One interesting point about the IGameStreamClient interface is the inclusion of the AsyncPattern property on the BeginReceiveGameData operation. I initially created this operation as a standard one way operation and it worked most of the time. However, as I disconnected clients and reconnected new ones game data wasn’t being passed properly. After researching the problem more I realized that because the service could take up to 7 seconds to return game data, things were getting hung up. By setting the AsyncPattern property to true on the BeginReceivedGameData operation and providing a corresponding EndReceiveGameData operation I was able to get around this problem and get everything running properly. I’ll provide more details on the implementation of these two methods later in this post. Once the interfaces were created I moved on to the game service class. The first order of business was to create a class that implemented the IGameStreamService interface. Since the service can be used by multiple clients wanting game data I added the ServiceBehavior attribute to the class definition so that I could set its InstanceContextMode to InstanceContextMode.Single (in effect creating a Singleton service object). Listing 3 shows the game service class as well as its fields and constructor.   [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, InstanceContextMode = InstanceContextMode.Single)] public class GameStreamService : IGameStreamService { object _Key = new object(); Game _Game = null; Timer _Timer = null; Random _Random = null; Dictionary<string, IGameStreamClient> _ClientCallbacks = new Dictionary<string, IGameStreamClient>(); static AsyncCallback _ReceiveGameDataCompleted = new AsyncCallback(ReceiveGameDataCompleted); public GameStreamService() { _Game = new Game(); _Timer = new Timer { Enabled = false, Interval = 2000, AutoReset = true }; _Timer.Elapsed += new ElapsedEventHandler(_Timer_Elapsed); _Timer.Start(); _Random = new Random(); }} Listing 3. The GameStreamService implements the IGameStreamService interface which defines a callback contract that allows the service class to push data back to the client. By implementing the IGameStreamService interface, GameStreamService must supply a GetTeamData() method which is responsible for supplying information about the teams that are playing as well as individual players.  GetTeamData() also acts as a client subscription method that tracks clients wanting to receive game data.  Listing 4 shows the GetTeamData() method. public void GetTeamData() { //Get client callback channel var context = OperationContext.Current; var sessionID = context.SessionId; var currClient = context.GetCallbackChannel<IGameStreamClient>(); context.Channel.Faulted += Disconnect; context.Channel.Closed += Disconnect; IGameStreamClient client; if (!_ClientCallbacks.TryGetValue(sessionID, out client)) { lock (_Key) { _ClientCallbacks[sessionID] = currClient; } } currClient.ReceiveTeamData(_Game.GetTeamData()); //Start timer which when fired sends updated score information to client if (!_Timer.Enabled) { _Timer.Enabled = true; } } Listing 4. The GetTeamData() method subscribes a given client to the game service and returns. The key the line of code in the GetTeamData() method is the call to GetCallbackChannel<IGameStreamClient>().  This method is responsible for accessing the calling client’s callback channel. The callback channel is defined by the IGameStreamClient interface shown earlier in Listing 2 and used by the server to communicate with the client. Before passing team data back to the client, GetTeamData() grabs the client’s session ID and checks if it already exists in the _ClientCallbacks dictionary object used to track clients wanting callbacks from the server. If the client doesn’t exist it adds it into the collection. It then pushes team data from the Game class back to the client by calling ReceiveTeamData().  Since the service simulates a basketball game, a timer is then started if it’s not already enabled which is then used to randomly send data to the client. When the timer fires, game data is pushed down to the client. Listing 5 shows the _Timer_Elapsed() method that is called when the timer fires as well as the SendGameData() method used to send data to the client. void _Timer_Elapsed(object sender, ElapsedEventArgs e) { int interval = _Random.Next(3000, 7000); lock (_Key) { _Timer.Interval = interval; _Timer.Enabled = false; } SendGameData(_Game.GetGameData()); } private void SendGameData(GameData gameData) { var cbs = _ClientCallbacks.Where(cb => ((IContextChannel)cb.Value).State == CommunicationState.Opened); for (int i = 0; i < cbs.Count(); i++) { var cb = cbs.ElementAt(i).Value; try { cb.BeginReceiveGameData(gameData, _ReceiveGameDataCompleted, cb); } catch (TimeoutException texp) { //Log timeout error } catch (CommunicationException cexp) { //Log communication error } } lock (_Key) _Timer.Enabled = true; } private static void ReceiveGameDataCompleted(IAsyncResult result) { try { ((IGameStreamClient)(result.AsyncState)).EndReceiveGameData(result); } catch (CommunicationException) { // empty } catch (TimeoutException) { // empty } } LIsting 5. _Timer_Elapsed is used to simulate time in a basketball game. When _Timer_Elapsed() fires the SendGameData() method is called which iterates through the clients wanting to be notified of changes. As each client is identified, their respective BeginReceiveGameData() method is called which ultimately pushes game data down to the client. Recall that this method was defined in the client callback interface named IGameStreamClient shown earlier in Listing 2. Notice that BeginReceiveGameData() accepts _ReceiveGameDataCompleted as its second parameter (an AsyncCallback delegate defined in the service class) and passes the client callback as the third parameter. The initial version of the sample application had a standard ReceiveGameData() method in the client callback interface. However, sometimes the client callbacks would work properly and sometimes they wouldn’t which was a little baffling at first glance. After some investigation I realized that I needed to implement an asynchronous pattern for client callbacks to work properly since 3 – 7 second delays are occurring as a result of the timer. Once I added the BeginReceiveGameData() and ReceiveGameDataCompleted() methods everything worked properly since each call was handled in an asynchronous manner. The final task that had to be completed to get the server working properly with HTTP Polling Duplex was adding configuration code into web.config. In the interest of brevity I won’t post all of the code here since the sample application includes everything you need. However, Listing 6 shows the key configuration code to handle creating a custom binding named pollingDuplexBinding and associate it with the service’s endpoint.   <bindings> <customBinding> <binding name="pollingDuplexBinding"> <binaryMessageEncoding /> <pollingDuplex maxPendingSessions="2147483647" maxPendingMessagesPerSession="2147483647" inactivityTimeout="02:00:00" serverPollTimeout="00:05:00"/> <httpTransport /> </binding> </customBinding> </bindings> <services> <service name="GameService.GameStreamService" behaviorConfiguration="GameStreamServiceBehavior"> <endpoint address="" binding="customBinding" bindingConfiguration="pollingDuplexBinding" contract="GameService.IGameStreamService"/> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services>   Listing 6. Configuring an HTTP Polling Duplex binding in web.config and associating an endpoint with it. Calling the Service and Receiving “Pushed” Data Calling the service and handling data that is pushed from the server is a simple and straightforward process in Silverlight. Since the service is configured with a MEX endpoint and exposes a WSDL file, you can right-click on the Silverlight project and select the standard Add Service Reference item. After the web service proxy is created you may notice that the ServiceReferences.ClientConfig file only contains an empty configuration element instead of the normal configuration elements created when creating a standard WCF proxy. You can certainly update the file if you want to read from it at runtime but for the sample application I fed the service URI directly to the service proxy as shown next: var address = new EndpointAddress("http://localhost.:5661/GameStreamService.svc"); var binding = new PollingDuplexHttpBinding(); _Proxy = new GameStreamServiceClient(binding, address); _Proxy.ReceiveTeamDataReceived += _Proxy_ReceiveTeamDataReceived; _Proxy.ReceiveGameDataReceived += _Proxy_ReceiveGameDataReceived; _Proxy.GetTeamDataAsync(); This code creates the proxy and passes the endpoint address and binding to use to its constructor. It then wires the different receive events to callback methods and calls GetTeamDataAsync().  Calling GetTeamDataAsync() causes the server to store the client in the server-side dictionary collection mentioned earlier so that it can receive data that is pushed.  As the server-side timer fires and game data is pushed to the client, the user interface is updated as shown in Listing 7. Listing 8 shows the _Proxy_ReceiveGameDataReceived() method responsible for handling the data and calling UpdateGameData() to process it.   Listing 7. The Silverlight interface. Game data is pushed from the server to the client using HTTP Polling Duplex. void _Proxy_ReceiveGameDataReceived(object sender, ReceiveGameDataReceivedEventArgs e) { UpdateGameData(e.gameData); } private void UpdateGameData(GameData gameData) { //Update Score this.tbTeam1Score.Text = gameData.Team1Score.ToString(); this.tbTeam2Score.Text = gameData.Team2Score.ToString(); //Update ball visibility if (gameData.Action != ActionsEnum.Foul) { if (tbTeam1.Text == gameData.TeamOnOffense) { AnimateBall(this.BB1, this.BB2); } else //Team 2 { AnimateBall(this.BB2, this.BB1); } } if (this.lbActions.Items.Count > 9) this.lbActions.Items.Clear(); this.lbActions.Items.Add(gameData.LastAction); if (this.lbActions.Visibility == Visibility.Collapsed) this.lbActions.Visibility = Visibility.Visible; } private void AnimateBall(Image onBall, Image offBall) { this.FadeIn.Stop(); Storyboard.SetTarget(this.FadeInAnimation, onBall); Storyboard.SetTarget(this.FadeOutAnimation, offBall); this.FadeIn.Begin(); } Listing 8. As the server pushes game data, the client’s _Proxy_ReceiveGameDataReceived() method is called to process the data. In a real-life application I’d go with a ViewModel class to handle retrieving team data, setup data bindings and handle data that is pushed from the server. However, for the sample application I wanted to focus on HTTP Polling Duplex and keep things as simple as possible.   Summary Silverlight supports three options when duplex communication is required in an application including TCP bindins, sockets and HTTP Polling Duplex. In this post you’ve seen how HTTP Polling Duplex interfaces can be created and implemented on the server as well as how they can be consumed by a Silverlight client. HTTP Polling Duplex provides a nice way to “push” data from a server while still allowing the data to flow over port 80 or another port of your choice.   Sample Application Download

    Read the article

  • Using the ASP.NET Cache to cache data in a Model or Business Object layer, without a dependency on System.Web in the layer - Part One.

    - by Rhames
    ASP.NET applications can make use of the System.Web.Caching.Cache object to cache data and prevent repeated expensive calls to a database or other store. However, ideally an application should make use of caching at the point where data is retrieved from the database, which typically is inside a Business Objects or Model layer. One of the key features of using a UI pattern such as Model-View-Presenter (MVP) or Model-View-Controller (MVC) is that the Model and Presenter (or Controller) layers are developed without any knowledge of the UI layer. Introducing a dependency on System.Web into the Model layer would break this independence of the Model from the View. This article gives a solution to this problem, using dependency injection to inject the caching implementation into the Model layer at runtime. This allows caching to be used within the Model layer, without any knowledge of the actual caching mechanism that will be used. Create a sample application to use the caching solution Create a test SQL Server database This solution uses a SQL Server database with the same Sales data used in my previous post on calculating running totals. The advantage of using this data is that it gives nice slow queries that will exaggerate the effect of using caching! To create the data, first create a new SQL database called CacheSample. Next run the following script to create the Sale table and populate it: USE CacheSample GO   CREATE TABLE Sale(DayCount smallint, Sales money) CREATE CLUSTERED INDEX ndx_DayCount ON Sale(DayCount) go INSERT Sale VALUES (1,120) INSERT Sale VALUES (2,60) INSERT Sale VALUES (3,125) INSERT Sale VALUES (4,40)   DECLARE @DayCount smallint, @Sales money SET @DayCount = 5 SET @Sales = 10   WHILE @DayCount < 5000  BEGIN  INSERT Sale VALUES (@DayCount,@Sales)  SET @DayCount = @DayCount + 1  SET @Sales = @Sales + 15  END Next create a stored procedure to calculate the running total, and return a specified number of rows from the Sale table, using the following script: USE [CacheSample] GO   SET ANSI_NULLS ON GO   SET QUOTED_IDENTIFIER ON GO   -- ============================================= -- Author:        Robin -- Create date: -- Description:   -- ============================================= CREATE PROCEDURE [dbo].[spGetRunningTotals]       -- Add the parameters for the stored procedure here       @HighestDayCount smallint = null AS BEGIN       -- SET NOCOUNT ON added to prevent extra result sets from       -- interfering with SELECT statements.       SET NOCOUNT ON;         IF @HighestDayCount IS NULL             SELECT @HighestDayCount = MAX(DayCount) FROM dbo.Sale                   DECLARE @SaleTbl TABLE (DayCount smallint, Sales money, RunningTotal money)         DECLARE @DayCount smallint,                   @Sales money,                   @RunningTotal money         SET @RunningTotal = 0       SET @DayCount = 0         DECLARE rt_cursor CURSOR       FOR       SELECT DayCount, Sales       FROM Sale       ORDER BY DayCount         OPEN rt_cursor         FETCH NEXT FROM rt_cursor INTO @DayCount,@Sales         WHILE @@FETCH_STATUS = 0 AND @DayCount <= @HighestDayCount        BEGIN        SET @RunningTotal = @RunningTotal + @Sales        INSERT @SaleTbl VALUES (@DayCount,@Sales,@RunningTotal)        FETCH NEXT FROM rt_cursor INTO @DayCount,@Sales        END         CLOSE rt_cursor       DEALLOCATE rt_cursor         SELECT DayCount, Sales, RunningTotal       FROM @SaleTbl   END   GO   Create the Sample ASP.NET application In Visual Studio create a new solution and add a class library project called CacheSample.BusinessObjects and an ASP.NET web application called CacheSample.UI. The CacheSample.BusinessObjects project will contain a single class to represent a Sale data item, with all the code to retrieve the sales from the database included in it for simplicity (normally I would at least have a separate Repository or other object that is responsible for retrieving data, and probably a data access layer as well, but for this sample I want to keep it simple). The C# code for the Sale class is shown below: using System; using System.Collections.Generic; using System.Data; using System.Data.SqlClient;   namespace CacheSample.BusinessObjects {     public class Sale     {         public Int16 DayCount { get; set; }         public decimal Sales { get; set; }         public decimal RunningTotal { get; set; }           public static IEnumerable<Sale> GetSales(int? highestDayCount)         {             List<Sale> sales = new List<Sale>();               SqlParameter highestDayCountParameter = new SqlParameter("@HighestDayCount", SqlDbType.SmallInt);             if (highestDayCount.HasValue)                 highestDayCountParameter.Value = highestDayCount;             else                 highestDayCountParameter.Value = DBNull.Value;               string connectionStr = System.Configuration.ConfigurationManager .ConnectionStrings["CacheSample"].ConnectionString;               using(SqlConnection sqlConn = new SqlConnection(connectionStr))             using (SqlCommand sqlCmd = sqlConn.CreateCommand())             {                 sqlCmd.CommandText = "spGetRunningTotals";                 sqlCmd.CommandType = CommandType.StoredProcedure;                 sqlCmd.Parameters.Add(highestDayCountParameter);                   sqlConn.Open();                   using (SqlDataReader dr = sqlCmd.ExecuteReader())                 {                     while (dr.Read())                     {                         Sale newSale = new Sale();                         newSale.DayCount = dr.GetInt16(0);                         newSale.Sales = dr.GetDecimal(1);                         newSale.RunningTotal = dr.GetDecimal(2);                           sales.Add(newSale);                     }                 }             }               return sales;         }     } }   The static GetSale() method makes a call to the spGetRunningTotals stored procedure and then reads each row from the returned SqlDataReader into an instance of the Sale class, it then returns a List of the Sale objects, as IEnnumerable<Sale>. A reference to System.Configuration needs to be added to the CacheSample.BusinessObjects project so that the connection string can be read from the web.config file. In the CacheSample.UI ASP.NET project, create a single web page called ShowSales.aspx, and make this the default start up page. This page will contain a single button to call the GetSales() method and a label to display the results. The html mark up and the C# code behind are shown below: ShowSales.aspx <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="ShowSales.aspx.cs" Inherits="CacheSample.UI.ShowSales" %>   <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">   <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server">     <title>Cache Sample - Show All Sales</title> </head> <body>     <form id="form1" runat="server">     <div>         <asp:Button ID="btnTest1" runat="server" onclick="btnTest1_Click"             Text="Get All Sales" />         &nbsp;&nbsp;&nbsp;         <asp:Label ID="lblResults" runat="server"></asp:Label>         </div>     </form> </body> </html>   ShowSales.aspx.cs using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls;   using CacheSample.BusinessObjects;   namespace CacheSample.UI {     public partial class ShowSales : System.Web.UI.Page     {         protected void Page_Load(object sender, EventArgs e)         {         }           protected void btnTest1_Click(object sender, EventArgs e)         {             System.Diagnostics.Stopwatch stopWatch = new System.Diagnostics.Stopwatch();             stopWatch.Start();               var sales = Sale.GetSales(null);               var lastSales = sales.Last();               stopWatch.Stop();               lblResults.Text = string.Format( "Count of Sales: {0}, Last DayCount: {1}, Total Sales: {2}. Query took {3} ms", sales.Count(), lastSales.DayCount, lastSales.RunningTotal, stopWatch.ElapsedMilliseconds);         }       } }   Finally we need to add a connection string to the CacheSample SQL Server database, called CacheSample, to the web.config file: <?xmlversion="1.0"?>   <configuration>    <connectionStrings>     <addname="CacheSample"          connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;Initial Catalog=CacheSample"          providerName="System.Data.SqlClient" />  </connectionStrings>    <system.web>     <compilationdebug="true"targetFramework="4.0" />  </system.web>   </configuration>   Run the application and click the button a few times to see how long each call to the database takes. On my system, each query takes about 450ms. Next I shall look at a solution to use the ASP.NET caching to cache the data returned by the query, so that subsequent requests to the GetSales() method are much faster. Adding Data Caching Support I am going to create my caching support in a separate project called CacheSample.Caching, so the next step is to add a class library to the solution. We shall be using the application configuration to define the implementation of our caching system, so we need a reference to System.Configuration adding to the project. ICacheProvider<T> Interface The first step in adding caching to our application is to define an interface, called ICacheProvider, in the CacheSample.Caching project, with methods to retrieve any data from the cache or to retrieve the data from the data source if it is not present in the cache. Dependency Injection will then be used to inject an implementation of this interface at runtime, allowing the users of the interface (i.e. the CacheSample.BusinessObjects project) to be completely unaware of how the caching is actually implemented. As data of any type maybe retrieved from the data source, it makes sense to use generics in the interface, with a generic type parameter defining the data type associated with a particular instance of the cache interface implementation. The C# code for the ICacheProvider interface is shown below: using System; using System.Collections.Generic;   namespace CacheSample.Caching {     public interface ICacheProvider     {     }       public interface ICacheProvider<T> : ICacheProvider     {         T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry);           IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry);     } }   The empty non-generic interface will be used as a type in a Dictionary generic collection later to store instances of the ICacheProvider<T> implementation for reuse, I prefer to use a base interface when doing this, as I think the alternative of using object makes for less clear code. The ICacheProvider<T> interface defines two overloaded Fetch methods, the difference between these is that one will return a single instance of the type T and the other will return an IEnumerable<T>, providing support for easy caching of collections of data items. Both methods will take a key parameter, which will uniquely identify the cached data, a delegate of type Func<T> or Func<IEnumerable<T>> which will provide the code to retrieve the data from the store if it is not present in the cache, and absolute or relative expiry policies to define when a cached item should expire. Note that at present there is no support for cache dependencies, but I shall be showing a method of adding this in part two of this article. CacheProviderFactory Class We need a mechanism of creating instances of our ICacheProvider<T> interface, using Dependency Injection to get the implementation of the interface. To do this we shall create a CacheProviderFactory static class in the CacheSample.Caching project. This factory will provide a generic static method called GetCacheProvider<T>(), which shall return instances of ICacheProvider<T>. We can then call this factory method with the relevant data type (for example the Sale class in the CacheSample.BusinessObject project) to get a instance of ICacheProvider for that type (e.g. call CacheProviderFactory.GetCacheProvider<Sale>() to get the ICacheProvider<Sale> implementation). The C# code for the CacheProviderFactory is shown below: using System; using System.Collections.Generic;   using CacheSample.Caching.Configuration;   namespace CacheSample.Caching {     public static class CacheProviderFactory     {         private static Dictionary<Type, ICacheProvider> cacheProviders = new Dictionary<Type, ICacheProvider>();         private static object syncRoot = new object();           ///<summary>         /// Factory method to create or retrieve an implementation of the  /// ICacheProvider interface for type <typeparamref name="T"/>.         ///</summary>         ///<typeparam name="T">  /// The type that this cache provider instance will work with  ///</typeparam>         ///<returns>An instance of the implementation of ICacheProvider for type  ///<typeparamref name="T"/>, as specified by the application  /// configuration</returns>         public static ICacheProvider<T> GetCacheProvider<T>()         {             ICacheProvider<T> cacheProvider = null;             // Get the Type reference for the type parameter T             Type typeOfT = typeof(T);               // Lock the access to the cacheProviders dictionary             // so multiple threads can work with it             lock (syncRoot)             {                 // First check if an instance of the ICacheProvider implementation  // already exists in the cacheProviders dictionary for the type T                 if (cacheProviders.ContainsKey(typeOfT))                     cacheProvider = (ICacheProvider<T>)cacheProviders[typeOfT];                 else                 {                     // There is not already an instance of the ICacheProvider in       // cacheProviders for the type T                     // so we need to create one                       // Get the Type reference for the application's implementation of       // ICacheProvider from the configuration                     Type cacheProviderType = Type.GetType(CacheProviderConfigurationSection.Current. CacheProviderType);                     if (cacheProviderType != null)                     {                         // Now get a Type reference for the Cache Provider with the                         // type T generic parameter                         Type typeOfCacheProviderTypeForT = cacheProviderType.MakeGenericType(new Type[] { typeOfT });                         if (typeOfCacheProviderTypeForT != null)                         {                             // Create the instance of the Cache Provider and add it to // the cacheProviders dictionary for future use                             cacheProvider = (ICacheProvider<T>)Activator. CreateInstance(typeOfCacheProviderTypeForT);                             cacheProviders.Add(typeOfT, cacheProvider);                         }                     }                 }             }               return cacheProvider;                 }     } }   As this code uses Activator.CreateInstance() to create instances of the ICacheProvider<T> implementation, which is a slow process, the factory class maintains a Dictionary of the previously created instances so that a cache provider needs to be created only once for each type. The type of the implementation of ICacheProvider<T> is read from a custom configuration section in the application configuration file, via the CacheProviderConfigurationSection class, which is described below. CacheProviderConfigurationSection Class The implementation of ICacheProvider<T> will be specified in a custom configuration section in the application’s configuration. To handle this create a folder in the CacheSample.Caching project called Configuration, and add a class called CacheProviderConfigurationSection to this folder. This class will extend the System.Configuration.ConfigurationSection class, and will contain a single string property called CacheProviderType. The C# code for this class is shown below: using System; using System.Configuration;   namespace CacheSample.Caching.Configuration {     internal class CacheProviderConfigurationSection : ConfigurationSection     {         public static CacheProviderConfigurationSection Current         {             get             {                 return (CacheProviderConfigurationSection) ConfigurationManager.GetSection("cacheProvider");             }         }           [ConfigurationProperty("type", IsRequired=true)]         public string CacheProviderType         {             get             {                 return (string)this["type"];             }         }     } }   Adding Data Caching to the Sales Class We now have enough code in place to add caching to the GetSales() method in the CacheSample.BusinessObjects.Sale class, even though we do not yet have an implementation of the ICacheProvider<T> interface. We need to add a reference to the CacheSample.Caching project to CacheSample.BusinessObjects so that we can use the ICacheProvider<T> interface within the GetSales() method. Once the reference is added, we can first create a unique string key based on the method name and the parameter value, so that the same cache key is used for repeated calls to the method with the same parameter values. Then we get an instance of the cache provider for the Sales type, using the CacheProviderFactory, and pass the existing code to retrieve the data from the database as the retrievalMethod delegate in a call to the Cache Provider Fetch() method. The C# code for the modified GetSales() method is shown below: public static IEnumerable<Sale> GetSales(int? highestDayCount) {     string cacheKey = string.Format("CacheSample.BusinessObjects.GetSalesWithCache({0})", highestDayCount);       return CacheSample.Caching.CacheProviderFactory. GetCacheProvider<Sale>().Fetch(cacheKey,         delegate()         {             List<Sale> sales = new List<Sale>();               SqlParameter highestDayCountParameter = new SqlParameter("@HighestDayCount", SqlDbType.SmallInt);             if (highestDayCount.HasValue)                 highestDayCountParameter.Value = highestDayCount;             else                 highestDayCountParameter.Value = DBNull.Value;               string connectionStr = System.Configuration.ConfigurationManager. ConnectionStrings["CacheSample"].ConnectionString;               using (SqlConnection sqlConn = new SqlConnection(connectionStr))             using (SqlCommand sqlCmd = sqlConn.CreateCommand())             {                 sqlCmd.CommandText = "spGetRunningTotals";                 sqlCmd.CommandType = CommandType.StoredProcedure;                 sqlCmd.Parameters.Add(highestDayCountParameter);                   sqlConn.Open();                   using (SqlDataReader dr = sqlCmd.ExecuteReader())                 {                     while (dr.Read())                     {                         Sale newSale = new Sale();                         newSale.DayCount = dr.GetInt16(0);                         newSale.Sales = dr.GetDecimal(1);                         newSale.RunningTotal = dr.GetDecimal(2);                           sales.Add(newSale);                     }                 }             }               return sales;         },         null,         new TimeSpan(0, 10, 0)); }     This example passes the code to retrieve the Sales data from the database to the Cache Provider as an anonymous method, however it could also be written as a lambda. The main advantage of using an anonymous function (method or lambda) is that the code inside the anonymous function can access the parameters passed to the GetSales() method. Finally the absolute expiry is set to null, and the relative expiry set to 10 minutes, to indicate that the cache entry should be removed 10 minutes after the last request for the data. As the ICacheProvider<T> has a Fetch() method that returns IEnumerable<T>, we can simply return the results of the Fetch() method to the caller of the GetSales() method. This should be all that is needed for the GetSales() method to now retrieve data from a cache after the first time the data has be retrieved from the database. Implementing a ASP.NET Cache Provider The final step is to actually implement the ICacheProvider<T> interface, and add the implementation details to the web.config file for the dependency injection. The cache provider implementation needs to have access to System.Web. Therefore it could be placed in the CacheSample.UI project, or in its own project that has a reference to System.Web. Implementing the Cache Provider in a separate project is my favoured approach. Create a new project inside the solution called CacheSample.CacheProvider, and add references to System.Web and CacheSample.Caching to this project. Add a class to the project called AspNetCacheProvider. Make the class a generic class by adding the generic parameter <T> and indicate that the class implements ICacheProvider<T>. The C# code for the AspNetCacheProvider class is shown below: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Caching;   using CacheSample.Caching;   namespace CacheSample.CacheProvider {     public class AspNetCacheProvider<T> : ICacheProvider<T>     {         #region ICacheProvider<T> Members           public T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry)         {             return FetchAndCache<T>(key, retrieveData, absoluteExpiry, relativeExpiry);         }           public IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry)         {             return FetchAndCache<IEnumerable<T>>(key, retrieveData, absoluteExpiry, relativeExpiry);         }           #endregion           #region Helper Methods           private U FetchAndCache<U>(string key, Func<U> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry)         {             U value;             if (!TryGetValue<U>(key, out value))             {                 value = retrieveData();                 if (!absoluteExpiry.HasValue)                     absoluteExpiry = Cache.NoAbsoluteExpiration;                   if (!relativeExpiry.HasValue)                     relativeExpiry = Cache.NoSlidingExpiration;                   HttpContext.Current.Cache.Insert(key, value, null, absoluteExpiry.Value, relativeExpiry.Value);             }             return value;         }           private bool TryGetValue<U>(string key, out U value)         {             object cachedValue = HttpContext.Current.Cache.Get(key);             if (cachedValue == null)             {                 value = default(U);                 return false;             }             else             {                 try                 {                     value = (U)cachedValue;                     return true;                 }                 catch                 {                     value = default(U);                     return false;                 }             }         }           #endregion       } }   The two interface Fetch() methods call a private method called FetchAndCache(). This method first checks for a element in the HttpContext.Current.Cache with the specified cache key, and if so tries to cast this to the specified type (either T or IEnumerable<T>). If the cached element is found, the FetchAndCache() method simply returns it. If it is not found in the cache, the method calls the retrievalMethod delegate to get the data from the data source, and then adds this to the HttpContext.Current.Cache. The final step is to add the AspNetCacheProvider class to the relevant custom configuration section in the CacheSample.UI.Web.Config file. To do this there needs to be a <configSections> element added as the first element in <configuration>. This will match a custom section called <cacheProvider> with the CacheProviderConfigurationSection. Then we add a <cacheProvider> element, with a type property set to the fully qualified assembly name of the AspNetCacheProvider class, as shown below: <?xmlversion="1.0"?>   <configuration>  <configSections>     <sectionname="cacheProvider" type="CacheSample.Base.Configuration.CacheProviderConfigurationSection, CacheSample.Base" />  </configSections>    <connectionStrings>     <addname="CacheSample"          connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;Initial Catalog=CacheSample"          providerName="System.Data.SqlClient" />  </connectionStrings>    <cacheProvidertype="CacheSample.CacheProvider.AspNetCacheProvider`1, CacheSample.CacheProvider, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null">  </cacheProvider>    <system.web>     <compilationdebug="true"targetFramework="4.0" />  </system.web>   </configuration>   One point to note is that the fully qualified assembly name of the AspNetCacheProvider class includes the notation `1 after the class name, which indicates that it is a generic class with a single generic type parameter. The CacheSample.UI project needs to have references added to CacheSample.Caching and CacheSample.CacheProvider so that the actual application is aware of the relevant cache provider implementation. Conclusion After implementing this solution, you should have a working cache provider mechanism, that will allow the middle and data access layers to implement caching support when retrieving data, without any knowledge of the actually caching implementation. If the UI is not ASP.NET based, if for example it is Winforms or WPF, the implementation of ICacheProvider<T> would be written around whatever technology is available. It could even be a standalone caching system that takes full responsibility for adding and removing items from a global store. The next part of this article will show how this caching mechanism may be extended to provide support for cache dependencies, such as the System.Web.Caching.SqlCacheDependency. Another possible extension would be to cache the cache provider implementations instead of storing them in a static Dictionary in the CacheProviderFactory. This would prevent a build up of seldom used cache providers in the application memory, as they could be removed from the cache if not used often enough, although in reality there are probably unlikely to be vast numbers of cache provider implementation instances, as most applications do not have a massive number of business object or model types.

    Read the article

  • How to open new view (call an activity) from options menu defined in XML? (android)

    - by Portablejim
    I cant seem to open a new view from an options menu item. The program keeps crashing as it applies the intent and listener to the item. I am just beginning, so please be nice. The current view is mnfsms, and the view I am trying to open is mnfsms_settings. I am developing for 1.5. Could someone please help me get the menu working. The menu (called options_menu.xml): <menu xmlns:android="http://schemas.android.com/apk/res/android"> <item android:id="@+id/settings_button" android:title="Settings" android:icon="@android:drawable/ic_menu_preferences" /> <item android:id="@+id/about_button" android:title="About" android:icon="@android:drawable/ic_menu_myplaces" /> </menu> The main view (called mnfsms.java): package com.example.mnfsms; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; public class mnfsms extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); /* OnClickListener myocl = new View.OnClickListener() { public void onClick(View v){ Intent myi = new Intent(mnfsms.this, mnfsms_settings.class); startActivity(myi); } };*/ } public boolean onCreateOptionsMenu(Menu menu) { MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.options_menu, menu); MenuItem mi_settings = (MenuItem)findViewById(R.id.settings_button); mi_settings.setIntent(new Intent(this, mnfsms_settings.class)); return true; } } The manifest: <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.mnfsms" android:versionCode="1" android:versionName="1.0"> <application android:icon="@drawable/icon" android:label="@string/app_name"> <activity android:name=".mnfsms" android:label="@string/main_window_name"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name=".mnfsms_settings" android:label="string/main_window_name"> </activity> </application> <uses-sdk android:minSdkVersion="3" /> </manifest> The stacktrace: 01-06 15:07:58.045: ERROR/AndroidRuntime(2123): Uncaught handler: thread main exiting due to uncaught exception 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): java.lang.NullPointerException 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at com.example.mnfsms.mnfsms.onCreateOptionsMenu(mnfsms.java:30) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at android.app.Activity.onCreatePanelMenu(Activity.java:2038) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at com.android.internal.policy.impl.PhoneWindow.preparePanel(PhoneWindow.java:421) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at com.android.internal.policy.impl.PhoneWindow.onKeyDownPanel(PhoneWindow.java:664) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at com.android.internal.policy.impl.PhoneWindow.onKeyDown(PhoneWindow.java:1278) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1735) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:2188) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2158) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at android.view.ViewRoot.handleMessage(ViewRoot.java:1490) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at android.os.Handler.dispatchMessage(Handler.java:99) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at android.os.Looper.loop(Looper.java:123) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at android.app.ActivityThread.main(ActivityThread.java:3948) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at java.lang.reflect.Method.invokeNative(Native Method) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at java.lang.reflect.Method.invoke(Method.java:521) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:782) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:540) 01-06 15:07:58.055: ERROR/AndroidRuntime(2123): at dalvik.system.NativeStart.main(Native Method)

    Read the article

  • Maven not setting classpath for dependencies properly

    - by Matthew
    OS name: "linux" version: "2.6.32-27-generic" arch: "i386" Family: "unix" Apache Maven 2.2.1 (r801777; 2009-08-06 12:16:01-0700) Java version: 1.6.0_20 I am trying to use the mysql dependency in with maven in ubuntu. If I move the "mysql-connector-java-5.1.14.jar" file that maven downloaded into my $JAVA_HOME/jre/lib/ext/ folder, everything is fine when I run the jar. I think I should be able to just specify the dependency in the pom.xml file and maven should take care of setting the classpath for the dependency jars automatically. Is this incorrect? My pom.xml file looks like this: <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.ion.common</groupId> <artifactId>TestPreparation</artifactId> <version>1.0-SNAPSHOT</version> <packaging>jar</packaging> <name>TestPrep</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> <configuration> <archive> <manifest> <addClasspath>true</addClasspath> <mainClass>com.ion.common.App</mainClass> </manifest> </archive> </configuration> </plugin> </plugins> </build> <dependencies> <!-- JUnit testing dependency --> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> <!-- MySQL database driver --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.14</version> <scope>compile</scope> </dependency> </dependencies> </project> The command "mvn package" builds it without any problems, and I can run it, but when the application attempts to access the database, this error is presented: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver at java.net.URLClassLoader$1.run(URLClassLoader.java:217) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:205) at java.lang.ClassLoader.loadClass(ClassLoader.java:321) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294) at java.lang.ClassLoader.loadClass(ClassLoader.java:266) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:186) at com.ion.common.Functions.databases(Functions.java:107) at com.ion.common.App.main(App.java:31) The line it is failing on is: Class.forName("com.mysql.jdbc.Driver"); Can anyone tell me what I'm doing wrong or how to fix it?

    Read the article

  • missing table in SQLite with specific version of HTC DESIRE HD

    - by William
    My application has a SQLite database in the asset folder. When the user launches my application, the database is created and the tables too. This works fine with a lot of devices (Nexus One, Htc Magic, SGS, X10… and even Htc Desire HD v2.2). My application works with all versions of Android (tested on my device (1.6, 2.2, 2.2.1 Htc Magic) and on the emulator (v1,5 until v2.3). I have just a problem with HTC DESIRE HD v2.2.1 1.72.405.3. The logcat: android.database.sqlite.SQLiteException: no such table: LISTE: , while compiling: select _id from LISTE at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2833) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2854) at android.app.ActivityThread.access$2300(ActivityThread.java:136) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2179) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:143) at android.app.ActivityThread.main(ActivityThread.java:5068) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:521) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) at dalvik.system.NativeStart.main(Native Method) Caused by: android.database.sqlite.SQLiteException: no such table: LISTE: , while compiling: select _id from LISTE at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method) at android.database.sqlite.SQLiteCompiledSql.compile(SQLiteCompiledSql.java:91) at android.database.sqlite.SQLiteCompiledSql.(SQLiteCompiledSql.java:64) at android.database.sqlite.SQLiteProgram.(SQLiteProgram.java:80) at android.database.sqlite.SQLiteQuery.(SQLiteQuery.java:46) at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:53) at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1417) at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1387) ... 11 more My application create the database but it doesn’t copy the tables of the file of the asset folder in data\data\packagename\databases\mydatabase. My code: public void createDataBase() throws IOException{ boolean dbExist = checkDataBase(); if(dbExist){ //do nothing - database already exist }else{ //By calling this method and empty database will be created into the default system path //of your application so we are gonna be able to overwrite that database with our database. this.getReadableDatabase(); try { copyDataBase(); } catch (IOException e) { throw new Error("Error copying database"); } } } private void copyDataBase() throws IOException{ //Open your local db as the input stream InputStream myInput = myContext.getAssets().open(DB_NAME); // Path to the just created empty db String outFileName = DB_PATH + DB_NAME; //Open the empty db as the output stream OutputStream myOutput = new FileOutputStream(outFileName); //transfer bytes from the inputfile to the outputfile byte[] buffer = new byte[1024]; int length; while ((length = myInput.read(buffer))!= -1){ if (length > 0){ myOutput.write(buffer, 0, length); } } //Close the streams myOutput.flush(); myOutput.close(); myInput.close(); } I think that the copydatabase function has a problem but I don't see. This code works fine with all devices except the HTC DESIRE HD v2.2.1 1.72.405.3. What problems might exist here for the HTC Desire with the given version above? How can this be remedied?

    Read the article

  • why is my intent not useful?

    - by user1634887
    This is my first to ask here. I write the code for a Broadcast A start another Broadcast B. But the Broadcast B didn't get the intent's value. Broadcast A:get the sms contain message and start B public void onReceive(Context context, Intent intent) { Object[] pdus=(Object[])intent.getExtras().get("pdus"); for(Object pdu:pdus) { byte[] date=(byte[])pdu; SmsMessage message=SmsMessage.createFromPdu(date); String sender=message.getOriginatingAddress(); String body=message.getMessageBody(); if(sender.equals(AppUtil.herPhone)&&body.regionMatches(0, AppUtil.herSmsText, 0, 18)) { Toast.makeText(context, body, Toast.LENGTH_LONG).show(); String [] bodyArray=body.split(" "); String longitude=bodyArray[1]; String latitude=bodyArray[2]; **Intent uiIntent=new Intent(); Bundle bundle=new Bundle(); bundle.putString("longitude", longitude); bundle.putString("latitude", latitude); uiIntent.putExtras(bundle); uiIntent.setAction("android.janmac.location"); context.sendBroadcast(uiIntent);** abortBroadcast(); } } } Boardcast B: it nest in an Activity. register: button.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { AppUtil.SendMessage(MainActivity.this); uiReceiver=new UIReceiver(); IntentFilter filter=new IntentFilter(); filter.addAction("android.janmac.location"); registerReceiver(uiReceiver, filter); } }); extend: private class UIReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { Log.v("location","uireceiver????!"); **Bundle bundle=new Bundle(); bundle=intent.getExtras(); herLongitude=Double.valueOf(bundle.getString("longitude")); herLatitude=Double.valueOf(bundle.getString("latitude"));** } } but the bundle couldn't get any values. here is log: 08-30 11:17:40.494: D/AndroidRuntime(2359): Shutting down VM 08-30 11:17:40.514: W/dalvikvm(2359): threadid=1: thread exiting with uncaught exception (group=0x40018560) 08-30 11:17:40.544: E/AndroidRuntime(2359): FATAL EXCEPTION: main 08-30 11:17:40.544: E/AndroidRuntime(2359): java.lang.RuntimeException: Error receiving broadcast Intent { act=android.janmac.location (has extras) } in com.example.locationclient.MainActivity$UIReceiver@40513690 08-30 11:17:40.544: E/AndroidRuntime(2359): at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:722) 08-30 11:17:40.544: E/AndroidRuntime(2359): at android.os.Handler.handleCallback(Handler.java:587) 08-30 11:17:40.544: E/AndroidRuntime(2359): at android.os.Handler.dispatchMessage(Handler.java:92) 08-30 11:17:40.544: E/AndroidRuntime(2359): at android.os.Looper.loop(Looper.java:130) 08-30 11:17:40.544: E/AndroidRuntime(2359): at android.app.ActivityThread.main(ActivityThread.java:3835) 08-30 11:17:40.544: E/AndroidRuntime(2359): at java.lang.reflect.Method.invokeNative(Native Method) 08-30 11:17:40.544: E/AndroidRuntime(2359): at java.lang.reflect.Method.invoke(Method.java:507) 08-30 11:17:40.544: E/AndroidRuntime(2359): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:864) 08-30 11:17:40.544: E/AndroidRuntime(2359): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:622) 08-30 11:17:40.544: E/AndroidRuntime(2359): at dalvik.system.NativeStart.main(Native Method) 08-30 11:17:40.544: E/AndroidRuntime(2359): Caused by: java.lang.NumberFormatException 08-30 11:17:40.544: E/AndroidRuntime(2359): at org.apache.harmony.luni.util.FloatingPointParser.parseDblImpl(Native Method) 08-30 11:17:40.544: E/AndroidRuntime(2359): at org.apache.harmony.luni.util.FloatingPointParser.parseDouble(FloatingPointParser.java:283) 08-30 11:17:40.544: E/AndroidRuntime(2359): at java.lang.Double.parseDouble(Double.java:318) 08-30 11:17:40.544: E/AndroidRuntime(2359): at java.lang.Double.valueOf(Double.java:356) 08-30 11:17:40.544: E/AndroidRuntime(2359): at com.example.locationclient.MainActivity$UIReceiver.onReceive(MainActivity.java:231) 08-30 11:17:40.544: E/AndroidRuntime(2359): at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:709) 08-30 11:17:40.544: E/AndroidRuntime(2359): ... 9 more enter code here

    Read the article

  • Eclipse Hell . . . Failed to read the project description file (.project)

    - by Kobojunkie
    I think Eclipse is trying to make me miserable. A couple of hours ago, my project was working and compiling well. Suddenly that all changed. Eclipse somehow wipes out all changes I have made to my files(activity, manifest etc.) I make sure to save often but when I go to run the project, I get the error that I have a build error. I checked and there was none, so I go to close Eclipse, so I can reopen and see if the errors will go away. Instead what happens is Eclipse wipes clean all my files and I end up with a project on disk with lots of blank code files. I try to run anyway, and I get the error message below. Failed to read the project description file (.project) for 'com.example.android.nfc.simulator.FakeTagsActivity.FakeTagsActivity'. The file has been changed on disk, and it now contains invalid information. The project will not function properly until the description file is restored to a valid state. Anyone have an idea what in the world this is about and how I can rectify this?

    Read the article

  • Play audio file data - Spring MVC

    - by Vijay Veeraraghavan
    In my web-application, I have various audio clips uploaded by the users in the database stored in the BLOB column. The audio files are low bit rate WAV files. The clips are secured, one can see only those clips he has uploaded. Instead of user downloading the clip and playing it in his player, I need it be steamed online in the web page itself. In the jsp I use the <audio> tag with the source mapping to the controller mappping url. <td> <audio controls><source src="recfile/${au.id}" type="audio/mpeg" /></audio> </td> Where, the recfile is the request mapping and the au.id is the audio id. In the controller I process the request like below @RequestMapping(value = "/recfile/{id}", method = RequestMethod.GET, produces = { MediaType.APPLICATION_OCTET_STREAM_VALUE }) public HttpEntity<byte[]> downloadRecipientFile(@PathVariable("id") int id, ModelMap model, HttpServletResponse response) throws IOException, ServletException { LOGGER.debug("[GroupListController downloadRecipientFile]"); VoiceAudioLibrary dGroup = audioClipService.findAudioClip(id); if (dGroup == null || dGroup.getAudioData() == null || dGroup.getAudioData().length <= 0) { throw new ServletException("No clip found/clip has not data, id=" + id); } HttpHeaders header = new HttpHeaders(); I tried this too //header.setContentType(new MediaType("audio", "mp3")); header.setContentType(new MediaType("audio", "vnd.wave"); header.setContentLength(dGroup.getAudioData().length); return new HttpEntity<byte[]>(dGroup.getAudioData(), header); } When the jsp loads, the controller get the request, it serves back the audio data fetched from the database, the jsp too shows the player with the controls. But when I play it nothing happens. Why is it? Am I missing anything in the configuration? Am I doing it right?

    Read the article

  • Make @JsonTypeInfo property optional

    - by Mark Peters
    I'm using @JsonTypeInfo to instruct Jackson to look in the @class property for concrete type information. However, sometimes I don't want to have to specify @class, particularly when the subtype can be inferred given the context. What's the best way to do that? Here's an example of the JSON: { "owner": {"name":"Dave"}, "residents":[ {"@class":"jacksonquestion.Dog","breed":"Greyhound"}, {"@class":"jacksonquestion.Human","name":"Cheryl"}, {"@class":"jacksonquestion.Human","name":"Timothy"} ] } and I'm trying to deserialize them into these classes (all in jacksonquestion.*): public class Household { private Human owner; private List<Animal> residents; public Human getOwner() { return owner; } public void setOwner(Human owner) { this.owner = owner; } public List<Animal> getResidents() { return residents; } public void setResidents(List<Animal> residents) { this.residents = residents; } } public class Animal {} public class Dog extends Animal { private String breed; public String getBreed() { return breed; } public void setBreed(String breed) { this.breed = breed; } } public class Human extends Animal { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } } using this config: @JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "@class") private static class AnimalMixin { } //... ObjectMapper objectMapper = new ObjectMapper(); objectMapper.getDeserializationConfig().addMixInAnnotations(Animal.class, AnimalMixin.class); Household household = objectMapper.readValue(json, Household.class); System.out.println(household); As you can see, the owner is declared as a Human, not an Animal, so I want to be able to omit @class and have Jackson infer the type as it normally would. When I run this though, I get org.codehaus.jackson.map.JsonMappingException: Unexpected token (END_OBJECT), expected FIELD_NAME: missing property '@class' that is to contain type id (for class jacksonquestion.Human) Since "owner" doesn't specify @class. Any ideas? One initial thought I had was to use @JsonTypeInfo on the property rather than the type. However, this cannot be leveraged to annotate the element type of a list.

    Read the article

  • Set width of Button in Android

    - by Mohit Deshpande
    How can I set a fixed width for an Android button? Everytime I try to set a fixed width it fills the current parent (the RelativeView). Here is my XML: <?xml version="1.0" encoding="utf-8"?> <RelativeLayout android:id="@+id/relativelayout" android:layout_width="fill_parent" android:layout_height="fill_parent" xmlns:android="http://schemas.android.com/apk/res/android"> <EditText android:layout_height="wrap_content" android:editable="false" android:layout_width="fill_parent" android:id="@+id/output"></EditText> <Button android:layout_height="wrap_content" android:id="@+id/Button01" android:layout_below="@id/output" android:text="7" android:layout_width="wrap_content"></Button> <Button android:layout_below="@id/output" android:layout_height="wrap_content" android:layout_width="wrap_content" android:id="@+id/Button02" android:layout_toRightOf="@+id/Button01" android:text="8"></Button> <Button android:layout_below="@id/output" android:layout_height="wrap_content" android:layout_width="wrap_content" android:id="@+id/Button03" android:layout_toRightOf="@+id/Button02" android:text="9"></Button> </RelativeLayout> How would I give it a FIXED width?

    Read the article

  • Maven 3 - duplicate declaration of version

    - by Taylor Leese
    I just upgraded to m2eclipse version 0.10 which includes an embedded Maven 3 and I'm now getting the following error when trying to run a build. I've already set Maven-Installations to my Maven 2 installation, but it had no effect. How do I resolve this? [INFO] Scanning for projects... [ERROR] The build could not read 1 project -> [Help 1] [ERROR] The project com.stuff:sutff-web:0.0.1-SNAPSHOT (C:\development\taylor\stuff\pom.xml) has 1 error [ERROR] 'dependencies.dependency.(groupId:artifactId:type:classifier)' must be unique: com.google.appengine:appengine-api-labs:jar -> duplicate declaration of version ${gae.version} [ERROR] [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch. [ERROR] Re-run Maven using the -X switch to enable full debug logging. [ERROR] [ERROR] For more information about the errors and possible solutions, please read the following articles: [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/ProjectBuildingException

    Read the article

  • JAXB 'generateElementProperty' tag not having any effect.

    - by Sionide21
    I am trying to remove the JAXBElement wrapper from a field that was a substitution group in my schema. I have tried both <jaxb:globalBindings generateElementProperty="false"/> and <jaxb:globalBindings> <xjc:generateElementProperty>false</xjc:generateElementProperty> </jaxb:globalBindings> But in both cases it seems to be completely ignored. Is there a problem trying to use this for substitution groups or am I missing something?

    Read the article

  • Displaying Multiple Tables in a Page in Jasper Reports using ireports/Jasper Assistant

    - by Karthikeyan
    Hi all, I have a report to be printed / exported to PDF format. for that i am using jasper reports. I have 8 individual pages to be exported. so i prepared 8 separate design files. In that 6 pages are having more static text and mere direct mapping and remaining two pages consists of table like data. one page contains huge table so i filled it directly with no problem by keeping a single table in detail band. now problem is that remaining one page. that page is having more than 5 small tables (two or four column). is t possible to have more that one table in a page in jasper reports ? i am using jasper reports and for designing jasper assistant/ireports.

    Read the article

  • Setting values and display Text in Android Spinner

    - by kaibuki
    Hi, I need help in setting up value and display text in spinner. as per now I am populating my spinner by array adapter e.g mySpinner.setAdapter(myAdapter); and as far as I know after doing this the display text and the value of spinner at same position is same. The other attribute that I can get from spinner is the position on the item. now in my case I want to make spinner like the drop down box, which we have in .NET. which holds a text and value. where as text is displayed and value is at back end. so if I change drop down box , I can either use its selected text or value. but its not happening in android spinner case. For Example: Text Value Cat 10 Mountain 5 Stone 9 Fish 14 River 13 Loin 17 so from above array I am only displaying non-living objects text, and what i want is that when user select them I get there value i.e. like when Mountain selected i get 5 I hope this example made my question a bit more clear... thankx

    Read the article

  • Null Validation on EditText box in Alert Dialog - Android

    - by LordSnoutimus
    Hi, I am trying to add some text validation to an edit text field located within an alert dialog box. It prompts a user to enter in a name. I want to add some validation so that if what they have entered is blank or null, it does not do anything apart from creating a Toast saying error. So far I have: AlertDialog.Builder alert = new AlertDialog.Builder(this); alert.setTitle("Record New Track"); alert.setMessage("Please Name Your Track:"); // Set an EditText view to get user input final EditText trackName = new EditText(this); alert.setView(trackName); alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int whichButton) { String textString = trackName.getText().toString(); // Converts the value of getText to a string. if (textString != null && textString.trim().length() ==0) { Context context = getApplicationContext(); CharSequence error = "Please enter a track name" + textString; int duration = Toast.LENGTH_LONG; Toast toast = Toast.makeText(context, error, duration); toast.show(); } else { SQLiteDatabase db = waypoints.getWritableDatabase(); ContentValues trackvalues = new ContentValues(); trackvalues.put(TRACK_NAME, textString); trackvalues.put(TRACK_START_TIME,tracktimeidentifier ); insertid=db.insertOrThrow(TRACK_TABLE_NAME, null, trackvalues); } But this just closes the Alert Dialog and then displays the Toast. I want the Alert Dialog to still be on the screen. Thanks

    Read the article

  • Android : Cannot cast from View to Button

    - by Mick
    I just started working with the Android, but seem to have come across a problem that I simply can't find the answer to. I get the error "Cannot cast from View to Button" on this line : Button myButton = (Button)findViewById(R.id.my_button); I've tried many different things to get it going, and I've searched for the answer, but for some reason it just refuses to work right. If anybody could point me in the right direction it'd be most appreciated. Thank you in advance.

    Read the article

  • android listview button control

    - by Josemalive
    Hi, I have an android listview filled with items. Every item has a button. This is the template of the my listview. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:paddingBottom="6dip" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" android:paddingLeft="5px" android:paddingTop="5px" android:paddingRight="5px" android:gravity="left"> <TextView android:id="@+id/TextView_test1" android:layout_width="200dip" android:paddingLeft="0px" android:layout_height="wrap_content"/> <TextView android:id="@+id/TextView_test2" android:layout_width="250dip" android:paddingLeft="0px" android:layout_height="wrap_content" android:layout_weight="1"/> <TextView android:id="@+id/TextView_test3" android:layout_width="400dip" android:paddingLeft="0px" android:layout_height="wrap_content" android:layout_weight="1"/> <Button android:id="@+id/Button_buttontest" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/Button_buttontest"/> </LinearLayout> How could i handle the click of each button in the activity code? Each button has the same id "Button_buttontest"? Thanks in advance. Best Regards. Jose

    Read the article

  • Android: Conversion to Dalvik format failed: Unable to execute dex: null

    - by Adam Haile
    I'm trying to use the SmugFig SmugMug API on Android. It was designed for J2SE I would imagine, so I'm not sure it will even work on Android, but I figured it was worth trying as opposed to trying to create my own API. When I load the project though, I get the following error: Conversion to Dalvik format failed: Unable to execute dex: null It doesn't say what package it fails on, just "Android Packaging Problem", but it did not do this before I added SmugFig and it's dependency JARS to the build path. Where should I look? Or does this mainly me that it just won't work with those libraries?

    Read the article

  • WebView and Cookies on Android

    - by dave smith
    I have an application on appspot that works fine through regular browser, however when used through Android WebView, it cannot set and read cookies. I am not trying to get cookies "outside" this web application BTW, once the URL is visited by WebView, all processing, ids, etc. can stay there, all I need is session management inside that application. First screen also loads fine, so I know WebView + server interactivity is not broken. I looked at WebSettings class, there was no call like setEnableCookies. I load url like this: public class MyActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); WebView webview = new WebView(this); setContentView(webview); webview.loadUrl([MY URL]); } .. } Any ideas?

    Read the article

  • Spring Security - Interactive login attempt was unsuccessful

    - by Taylor L
    I've been trying to track down why Spring Security isn't creating the SPRING_SECURITY_REMEMBER_ME_COOKIE so I turned on logging for org.springframework.security.web.authentication.rememberme. At first glance, the logs make it seem like the login is failing but the login is actually successful in the sense that if I navigate to a page that requires authentication I am not redirected back to the login page. However, the logs appear to be saying the login credentials are invalid. Any ideas as to what is going on? Mar 16, 2010 10:05:56 AM org.springframework.security.web.authentication.rememberme.PersistentTokenBasedRememberMeServices onLoginSuccess FINE: Creating new persistent login for user [email protected] Mar 16, 2010 10:10:07 AM org.springframework.security.web.authentication.rememberme.AbstractRememberMeServices loginFail FINE: Interactive login attempt was unsuccessful. Mar 16, 2010 10:10:07 AM org.springframework.security.web.authentication.rememberme.AbstractRememberMeServices cancelCookie FINE: Cancelling cookie <http auto-config="false"> <intercept-url pattern="/css/**" filters="none" /> <intercept-url pattern="/img/**" filters="none" /> <intercept-url pattern="/js/**" filters="none" /> <intercept-url pattern="/app/admin/**" filters="none" /> <intercept-url pattern="/app/login/**" filters="none" /> <intercept-url pattern="/app/register/**" filters="none" /> <intercept-url pattern="/app/error/**" filters="none" /> <intercept-url pattern="/" filters="none" /> <intercept-url pattern="/**" access="ROLE_USER" /> <logout logout-success-url="/" /> <form-login login-page="/app/login" default-target-url="/" authentication-failure-url="/app/login?login_error=1" /> <session-management invalid-session-url="/app/login" /> <remember-me services-ref="rememberMeServices" key="myKey" /> </http> <authentication-manager alias="authenticationManager"> <authentication-provider user-service-ref="userDetailsService"> <password-encoder hash="sha-256" base64="true"> <salt-source user-property="username" /> </password-encoder> </authentication-provider> </authentication-manager> <beans:bean id="userDetailsService" class="com.my.service.auth.UserDetailsServiceImpl" /> <beans:bean id="rememberMeServices" class="org.springframework.security.web.authentication.rememberme.PersistentTokenBasedRememberMeServices"> <beans:property name="userDetailsService" ref="userDetailsService" /> <beans:property name="tokenRepository" ref="persistentTokenRepository" /> <beans:property name="key" value="myKey" /> </beans:bean> <beans:bean id="persistentTokenRepository" class="com.my.service.auth.PersistentTokenRepositoryImpl" />

    Read the article

  • Spring 3.0 making JSON response using jackson message converter

    - by dupdup
    i configure my messageconverter as Jackson's then class Foo{int x; int y} and in controller @ResponseBody public Foo method(){ return new Foo(3,4) } from that i m expecting to return a JSON string {x:'3',y:'4'} from server without any other configuration. but getting 404 error response to my ajax request If the method is annotated with @ResponseBody, the return type is written to the response HTTP body. The return value will be converted to the declared method argument type using HttpMessageConverters. Am I wrong ? or should I convert my response Object to Json string myself using serializer and then returning that string as response.(I could make string responses correctly) or should I make some other configurations ? like adding annotations for class Foo here is my conf.xml <bean id="jacksonMessageConverter" class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"> <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"> <property name="messageConverters"> <list> <ref bean="jacksonMessageConverter"/> </list> </property>

    Read the article

  • Jackson Vs. Gson

    - by Null Pointer
    After searching through some existing libraries for JSON, I have finally ended up with these two: Jackson Google GSon I am a bit partial towards GSON, but word on the net is that GSon suffers from certain celestial performance issue. I am continuing my comparison, in the meanwhile I was looking for help to make up my mind.

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 751 752 753 754 755 756 757 758 759 760 761 762  | Next Page >