Does writing data to server using Java URL class require response from server?
- by gigadot
I am trying to upload files using Java URL class and I have found a previous question on stack-overflow which explains very well about the details, so I try to follow it. And below is my code adopted from the sniplet given in the answer.
My problem is that if I don't make a call to one of connection.getResponseCode() or connection.getInputStream() or connection.getResponseMessage() or anything which is related to reponse from the server, the request will never be sent to server. Why do I need to do this? Or is there any way to write the data without getting the response?
P.S. I have developed a server-side uploading servlet which accepts multipart/form-data and save it to files using FileUpload. It is stable and definitely working without any problem so this is not where my problem is generated.
import java.io.Closeable;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import org.apache.commons.io.IOUtils;
public class URLUploader {
public static void closeQuietly(Closeable... objs) {
for (Closeable closeable : objs) {
IOUtils.closeQuietly(closeable);
}
}
public static void main(String[] args) throws IOException {
File textFile = new File("D:\\file.zip");
String boundary = Long.toHexString(System.currentTimeMillis()); // Just generate some unique random value.
HttpURLConnection connection = (HttpURLConnection) new URL("http://localhost:8080/upslet/upload").openConnection();
connection.setDoOutput(true);
connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);
OutputStream output = output = connection.getOutputStream();
PrintWriter writer = writer = new PrintWriter(output, true);
// Send text file.
writer.println("--" + boundary);
writer.println("Content-Disposition: form-data; name=\"file1\"; filename=\"" + textFile.getName() + "\"");
writer.println("Content-Type: application/octet-stream");
FileInputStream fin = new FileInputStream(textFile);
writer.println();
IOUtils.copy(fin, output);
writer.println();
// End of multipart/form-data.
writer.println("--" + boundary + "--");
output.flush();
closeQuietly(fin, writer, output);
// Above request will never be sent if .getInputStream() or .getResponseCode() or .getResponseMessage() does not get called.
connection.getResponseCode();
}
}
