midletdemo.java~11~

J2ME高级用户界面的学习代码

//MIDletDemo.java

package ORA.ch3;

import java.util.Timer;
import java.util.TimerTask;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

public class MIDletDemo extends MIDlet
{
  private boolean started = false;
  private Thread thread;
  private int timerInterval;
  private Timer timer;
  private TimerTask task;

  public MIDletDemo() {
    System.out.println("**************Constructor Executed!**************");
    String interval = getAppProperty("Timer-Interval");
    timerInterval = Integer.parseInt(interval);
    System.out.println("Timer interval is " + interval);
  }

  protected void startApp() throws MIDletStateChangeException
  {
    if (!started)
    {
      started = true;
      System.out.println("startApp called for the first time!");
      startTimer();
    }
    else
    {
      System.out.println("startApp called following pause!");
    }

    synchronized (this)
    {
      if (thread == null)
      {
        thread = new Thread()
        {
          public void run()
          {
            System.out.println("Thread running!");
            while (thread == this)
            {
              try {
                Thread.sleep(1000);
                System.out.println("Thread still alive!");
              }
              catch (InterruptedException ex) {
              }
            }
            System.out.println("Thread terminating!");
          }
        };
      }
    };
    thread.start();
  }

  protected void pauseApp()
  {
    System.out.println("pauseApp called!");
    synchronized (this)
    {
      if (thread != null)
      {
        thread = null;
      }
    }
  }

  protected void destroyApp(boolean unconditional) throws
      MIDletStateChangeException
  {
    System.out.println("destroyApp called - unconditional = " + unconditional);
    if (thread != null) {
      Thread bgThread = thread;
      thread = null;
      try {
        bgThread.join();
      }
      catch (InterruptedException ex) {
      }
    }
    stopTimer();
  }

  private void startTimer()
  {
    task = new TimerTask() {
      private boolean isPaused;
      private int count;

      public void run() {
        System.out.println("Timer scheduled!");
        if (count++ == 4)
        {
          //终止MIDlet
          try {
            MIDletDemo.this.destroyApp(true);
          }
          catch (MIDletStateChangeException ex) {
          }
          MIDletDemo.this.notifyDestroyed();
          return;
        }

        if (isPaused)
        {
          System.out.println(">> Resuming MIDlet");
          MIDletDemo.this.resumeRequest();
          isPaused = false;
        }
        else
        {
          System.out.println(">> Pauseing MIDlet");
          isPaused = true;
          MIDletDemo.this.pauseApp();
          MIDletDemo.this.notifyPaused();
        } //else
      } //run()
    }; //new

    timer = new Timer();
    timer.schedule(task,timerInterval,timerInterval);
    System.out.println("Timer Started!");
  } //startTimer();

  private void stopTimer()
  {
    if(timer != null)
    {
      System.out.print("Stopping the timer");
      timer.cancel();
    }
  }//stopTimer()
}//MIDletDemo