progressgauge.java

j2me 校园手机客户端上载传输程序

package com.enterprisej2me.iFeedBack.midp.Task;
 
import java.util.*;
import javax.microedition.lcdui.*;

public class ProgressGauge extends Form implements Runnable, CommandListener {

  private boolean stopped; // whether this is stopped
  private Gauge g;
  private Thread th; // Gauge thread.
  private BackgroundTask bktk; // The worker thread.
  private Displayable prevScreen; // The screen to go to if the Gauge is 
                                  // failed or stopped mannually.
  private Displayable nextScreen = null;
  private Alert alertScreen = null;

  private Display display;
  private static final Command cancelCmd =
                               new Command("Cancel",Command.BACK,2);

  public ProgressGauge(BackgroundTask b, String title, 
                       Display d, Displayable p) {
    super("Please wait...");
    prevScreen = p;
    bktk = b; // the worker (background) thread
    init(title, d);
  }


  private void init(String title, Display d) {
    try {
      display = d;
      th = new Thread(this);
      th.setPriority(Thread.MIN_PRIORITY);

      g  = new Gauge(title, false, 10, 0);
      append(g);
      addCommand(cancelCmd);
      setCommandListener(this);

      start();
    } catch (Exception e) {
      System.out.println("Error starting the Gauge");
      display.setCurrent(prevScreen);
    }
  }

  public void start() {
     stopped = false;
    // only start the tread if not alive
    if (th.isAlive() == false) {
      th.start();
    }
  }

  public void stop() {
    if (nextScreen == null) {
      nextScreen = prevScreen;
    }
    stopped = true;
  }

  public void run() {

    // In rare cases, stop() might be called after the thread
    // start() called but run() is not yet called ...
    if ( !stopped ) 
      display.setCurrent(this);

    // do until notified to stop/quit
    while (stopped == false) {
      for(int i=0; i < g.getMaxValue(); i++) {
        g.setValue(i);
        th.yield();
      }
      g.setValue(0);
    }
    g = null;

    if (alertScreen == null) {
      display.setCurrent(nextScreen);
    } else {
      display.setCurrent(alertScreen, nextScreen);
    }
  }

  public void setNextScreen (Alert a, Displayable d) {
    alertScreen = a;
    nextScreen = d;
  }

  public void setNextScreen (Displayable d) {
    alertScreen = null;
    nextScreen = d;
  }

  public void commandAction(Command c, Displayable d) {
    if (c == cancelCmd) {
      stop();
      bktk.stop();
      display.setCurrent(prevScreen);
    }
  }

}