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How to use singleinstance service with a JWS application

843802Dec 14 2007 — edited Jan 27 2008
Hello,

I have a Swing application and i am using Java web start to deploy on the user machines.
I want to know how to implement the single instance service. so that only one instance os the application is running.

Where should i use the singleinstance class provided by JNLP api.

for ex:

package test;

import java.awt.BorderLayout;

import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

import javax.swing.border.EmptyBorder;
import java.util.Date;

// classes of the web-start API, used in this example.
import javax.jnlp.SingleInstanceListener;
import javax.jnlp.SingleInstanceService;
import javax.jnlp.ServiceManager;
import javax.jnlp.UnavailableServiceException;

/** A test of the SingleInstanceService using the web-start API.
@author Andrew Thompson
@version 2007/1/8
*/
public class SingleInstanceApplication
extends JFrame
implements SingleInstanceListener {

/** A simple editing area. */
JTextArea document;

/** Assemble the GUI. */
SingleInstanceApplication() {
super("JNLP API single instance service");

try {
SingleInstanceService singleInstanceService =
(SingleInstanceService)ServiceManager.
lookup("javax.jnlp.SingleInstanceService");
// add the listener to this application!
singleInstanceService.addSingleInstanceListener(
(SingleInstanceListener)this );
} catch(UnavailableServiceException use) {
use.printStackTrace();
System.exit(-1);
}

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

document = new JTextArea(
"Try openning another version of this application\n");
document.setEditable(false);

JPanel main = new JPanel(new BorderLayout());
main.add(new JScrollPane(document));
main.setBorder( new EmptyBorder(8,8,8,8) );

getContentPane().add(main);

pack();
setSize(400,300);
setLocationRelativeTo(null);
}

/** Specified by the SingleInstanceListener interface
@param args The command line parameters used for this invocation */
public void newActivation(String[] args) {
StringBuffer sb = new StringBuffer();
for (int ii=0; ii<args.length; ii++) {
sb.append("'" + args[ii] + "' ");
}
String message = "Got new args: " + sb.toString();
// this usually serves to alert the user the app.
// wants attention. On Win. it will flash the
// apps. icon in the task bar.
JOptionPane.showMessageDialog(this, message);
// also add the new args and time to the document.
document.append( new Date() + "\t" + message + "\n" );
}

/** Construct the GUI and display it. If the user double clicked
a file to start the application, begin measures to load that file. */
public static void main(String[] args) {
SingleInstanceApplication app =
new SingleInstanceApplication();
app.setVisible(true);
}
}



in my progrma there are many clasess where should i use this.

Pls help new bie!!

Thanks and Regards

Comments

843806
Add a JTextArea to your frame, create a TextAreaOutputStream with it, and use System.setOut(...) to set System.ouot
/*
 * Created on Mar 13, 2005 by @author Tom Jacobs
 *
 */
package tjacobs;

import java.io.IOException;
import java.io.OutputStream;

import javax.swing.JTextArea;
import javax.swing.text.JTextComponent;

/**
 * TextAreaOutputStream creates an outputstream that will output to the
 * given textarea. Useful in setting System.out
 */
public class TextAreaOutputStream extends OutputStream {
	public static final int DEFAULT_BUFFER_SIZE = 1;
	
	JTextArea mText;
	byte mBuf[];
	int mLocation;
	public TextAreaOutputStream(JTextArea component) {
		this(component, DEFAULT_BUFFER_SIZE);
	}

	public TextAreaOutputStream(JTextArea component, int bufferSize) {
		mText = component;
		if (bufferSize < 1) bufferSize = 1;
		mBuf = new byte[bufferSize];
		mLocation = 0;
	}
	@Override
	public void write(int arg0) throws IOException {
		//System.err.println("arg = "  + (char) arg0);
		mBuf[mLocation++] = (byte)arg0;
		if (mLocation == mBuf.length) {
			flush();
		}
	}
	
	public void flush() {
		mText.append(new String(mBuf, 0, mLocation));
		mLocation = 0;
/*
		try {
			Thread.sleep(1);
		}
		catch (Exception ex) {}
	}
	*/
	}
}
843806
Thanks for the sample, it's very useful :)
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Locked on Feb 24 2008
Added on Dec 14 2007
#java-web-start-jnlp
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