I have Java Applet(J2EE), I want to make it accessible only to a certain set of users,by authenticating them using username and password.What is the the best way of doing this?
I'm using a MySQL database and accessing it through Java.
PreparedStatement prep1 = this.connection.prepareStatement("UPDATE user_table
SET Level = 'Super'
WHERE Username = ?");
prep1.setString(1, username);
The update statement above works fine however I'd like to get the number of rows affected with this statement. Is this possible please?
This is simply for fun. This will not be used for any actual encryption. I'm only first year comp sci student and love cryptography.
This took a long time to get working. At approximately N = 18, it begins breaking down. It won't encrypt messages properly after that point. I'm not sure why. Any insights? I'd also appreciate any links you could provide me to tutorials or interesting reading about Cryptography.
import java.math.BigInteger;
import java.security.SecureRandom;
/**
* Cryptography.
*
* Generates public and private keys used in encryption and
* decryption
*
*/
public class RSA
{
private final static BigInteger one = new BigInteger("1");
private final static SecureRandom random = new SecureRandom();
// prime numbers
private BigInteger p;
private BigInteger q;
// modulus
private BigInteger n;
// totient
private BigInteger t;
// public key
private BigInteger e;
// private key
private BigInteger d;
private String cipherText;
/**
* Constructor for objects of class RSA
*/
public RSA(int N)
{
p = BigInteger.probablePrime(N/2, random);
q = BigInteger.probablePrime(N/2, random);
// initialising modulus
n = p.multiply(q);
// initialising t by euclid's totient function (p-1)(q-1)
t = (p.subtract(one)).multiply(q.subtract(one));
// initialising public key ~ 65537 is common public key
e = new BigInteger("65537");
}
public int generatePrivateKey()
{
d = e.modInverse(t);
return d.intValue();
}
public String encrypt(String plainText)
{
String encrypted = "";
int j = 0;
for(int i = 0; i < plainText.length(); i++){
char m = plainText.charAt(i);
BigInteger bi1 = BigInteger.valueOf(m);
BigInteger bi2 = bi1.modPow(e, n);
j = bi2.intValue();
m = (char) j;
encrypted += m;
}
cipherText = encrypted;
return encrypted;
}
public String decrypt()
{
String decrypted = "";
int j = 0;
for(int i = 0; i < cipherText.length(); i++){
char c = cipherText.charAt(i);
BigInteger bi1 = BigInteger.valueOf(c);
BigInteger bi2 = bi1.modPow(d, n);
j = bi2.intValue();
c = (char) j;
decrypted += c;
}
return decrypted;
}
}
Hi i'm working in task queue concept.... First i struggled to program using task queue and i asked many doubts in stack overflow and Google app engine java. After a search i got a sample program for task queue. http://gaejexperiments.wordpress.com/2009/11/24/episode-10-using-the-task-queue-service/ It will very useful for beginners Like me.
Regards,
Sharun.
What is the best was to retrieve a file from a server using SFTP (as opposed to FTPS) using Java?
I'll leave the particular definition of best up to you but in my mind it should include free :)
I've found that java.lang.Ingteger implementation of compareTo method looks as follows:
public int compareTo(Integer anotherInteger) {
int thisVal = this.value;
int anotherVal = anotherInteger.value;
return (thisVal<anotherVal ? -1 : (thisVal==anotherVal ? 0 : 1));
}
The question is why use comparison instead of subtraction:
return thisVal - anotherVal;
Hi,
I would like to open a webpage and run a javascript function from within a java app.
For example I would like to open the page www.mytestpage.com and run the following javascript code:document.getElementById("txtEmail").value="[email protected]";submit();void(0);
This works in a browser...how can I do it programatically?
Thanks!
Hi all! I'm making an android program that retrieves content of a webpage using HttpURLConnection. I'm new to both Java and Android.
Problem is: Reader reads whole page source, but in the last while iteration it doesn't append to stringBuffer that last part.
Using debbuger I have determined that, in the last loop iteration, string buff is created, but stringBuffer just doesnt append it.
I need to parse retrieved content. Is there any better way to handle the content for parsing than using strings. I've read on numerous other sites that string size in Java is limited only by available heap size. I've tried with StringBuilder too.
Anyone know what could be the problem. Btw feel free to suggest any improvements to the code.
Thanks!
URL u;
try {
u = new URL("http://feeds.timesonline.co.uk/c/32313/f/440134/index.rss");
HttpURLConnection c = (HttpURLConnection) u.openConnection();
c.setRequestProperty("User-agent","Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; InfoPath.1; .NET CLR 2.0.50727)");
c.setRequestMethod("GET");
c.setDoOutput(true);
c.setReadTimeout(3000);
c.connect();
StringBuffer stringBuffer = new StringBuffer("");
InputStream in = c.getInputStream();
InputStreamReader inp = new InputStreamReader(in);
BufferedReader reader = new BufferedReader(inp);
char[] buffer = new char[3072];
int len1 = 0;
while ( (len1 = reader.read(buffer)) != -1 )
{
String buff = new String(buffer,0,len1);
stringBuffer.append(buff);
}
String stranica = new String(stringBuffer);
c.disconnect();
reader.close();
inp.close();
in.close();
Hi,
After I read Bloch's discussion http://www.infoq.com/news/2010/04/bloch_java_future
I started to think about "Do I have to switch to scala for new web developements" or is java preferred in all cases. What is your opinion ?
Thanks,
I'm writing an application which monitors the person’s mouse and keyboard. If they have not used the keyboard or mouse for 1 minute, it should pops up a message which says “You have not used the mouse or keyboard for 1 minute” and an OK button.
How do I do this in Java?
I have been working with the Swing library for a long time, I'm working on a new project for school and due to the nature of the program it can't look like a generic/boring swing gui. So my question is does anyone know of an interesting java gui library that is not swing or awt?
I want to create a TreeMap in Java with a custom sort order. The sorted keys which are string need to be sorted according to the second character. The values are also string.
Sample map:
Za,FOO
Ab,Bar
Hello,
In which case should you use primitive types(int) or complex types(Integer)?
Ex:
http://stackoverflow.com/questions/2508918/why-java-compiler-does-not-like-integer-as-type-for-values-in-hashmap this example works with Integer type. Should we always use Integer as a complex type?
I have created a Java Swing application. It works fine.
I have created application file (.app) for that application using jar bundler.
But the main problem is that my application does not open if I click it on the Dock. I am using Mac OS. How I can launch my application by clicking on Dock
Thanks
Sunil Kumar Sahoo
how to do the 3D Animation in java? what are the packages to be needed? i am very newbie about this topic. Sample Code, Tutorials and articles are more thankful. Tell me how i have to start please?
NOTE: its for Mobile Appication.
I have an android app that I am trying to get a file path for a SAX parser. I have the following structure:
assets:(Where my xml file is)
src(same level as assets)
com
msi
androidrss(The calling java file is in here)
I tried several variations of this:
InputSource is = new InputSource("file://../../../../assets/Rss.xml");
But I always get a FNF Exception
Any suggestions?
Thanks
I have database with oracle number type. Could there any possible issues with using java Double when updating table with numeric column. Should i switch BigDecimal or Double is approriate type.
As I fas as I know, BigDecimal is used when arbitrary precision required, when deal with prices for example.
Consider simple API updatePrice(Double d) Should i persist double as is or BigDecimal.valueOf(d) is preferable ?
In my code I am using java.sql.PreparedStatement.
I then execute the setString() method to populate the wildcards of the prepared statement.
Is there a way for me to retrieve (and print out) the final query before the executeQuery() method is called and the query is executed? I Just want this for debugging purposes.
Thanks.
What JAVA library should I be using to Hash passwords for storage in a database?
I was hoping to just take the plain text password, add a random salt, then store the salt and the hashed password in the database.
Then when a user wanted to log in, I could just take their submitted password, add the random salt from their account information, hash it and see if it equates to the stored hash password with their account information.
I've looked around for a good example of this, but I haven't run into one yet. I want to pass a custom string array from java to oracle and back, using the IBATIS framework. Does anyone have a good link to an example? I'm calling stored procs from IBATIS.
Thanks
In my java application i am having latitude information in this format 28"41'44.13597 .
My need is to convert the same information into 28.705450.
Please help through code or any references
Thanks in advance
Hello,
I am writing a user defined function to DB2 on AS/400 in Java and the strangest thing happen..
I am always getting the same result from the function even when i am changing it, even if i am dropping it and create it again and even when i specify NOT DETERMINISTIC..
Does any one have ever encountered a behavior like that?
I have line in JAVA and in while i get number:
i = gzipinputstream1.read(abyte0, j, 4096);
From while number:
959
1552
1577
1617
1680
when i want use in php:
$i = fread($handle, 959):
while return:
959,
959,
959,
5
How make that in PHP result will be the some. thanks
I'm new to java and i'm trying to find a way of incrementing through an user input IP address range.
For example from 192.168.0.1 to 192.168.0.255. However the way my application works at the moment is the take the from and to ip addresses as a String.
Is there a way I can increment through all the ip addresses the user input from and to?
Hope this makes sense and please dont flame me, I have looked for an answer!