Source Code : Preventing multiple instances of an application: The file lock technique

Java Is Open Source Programming Language You Can Download From Java and Java Libraries From http://www.oracle.com. Click Here to download
We provide this code related to title for you to solve your developing problem easily. Libraries which is import in this program you can download from http://www.oracle.com. Click Here or search from google with Libraries Name you get jar file related it

Preventing multiple instances of an application: The file lock technique

 

import java.io.File;
import java.io.RandomAccessFile;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;

class JustOneLock {
  private String appName;

  FileLock lock;

  FileChannel channel;

  public JustOneLock(String appName) {
    this.appName = appName;
  }

  public boolean isAppActive() throws Exception{
    File file = new File(System.getProperty("user.home"), appName + ".tmp");
    channel = new RandomAccessFile(file, "rw").getChannel();

    lock = channel.tryLock();
    if (lock == null) {
      lock.release();
      channel.close();
      return true;
    }
    Runtime.getRuntime().addShutdownHook(new Thread() {
      public void run() {
        try {
          lock.release();
          channel.close();
        } catch (Exception e) {
          e.printStackTrace();
        }
      }
    });
    return false;
  }
}

public class Main {
  public static void main(String[] args)throws Exception {
    JustOneLock ua = new JustOneLock("JustOneId");
    if (ua.isAppActive()) {
      System.out.println("Already active.");
      System.exit(1);
    } else {
      System.out.println("NOT already active.");
    }
  }
}

   
  

Thank with us