animationtest.java

JAVA编程百例书中各章节的所有例子的源代码,包括套接字编程

package example.animate;

import java.io.*;
import java.util.*;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;

//该MIDlet用于显示一个动画。
public class AnimationTest
    extends MIDlet
    implements CommandListener {
  //定义动画的帧数
  private static final int BIRD_FRAMES = 7;

  //窗体上同时显示的动画数
  private static final int NUM_BIRDS = 5;
  private Display display;
  private Timer timer = new Timer();
  private AnimatedImage[] birds;
  private Random random = new Random();

  public static final Command exitCommand = new Command("退出", Command.EXIT, 1);

  //响应退出按钮
  public void commandAction(Command c, Displayable d) {
    if (c == exitCommand) {
      exitMIDlet();
    }
  }

  //销毁MIDLET
  protected void destroyApp(boolean unconditional) throws
      MIDletStateChangeException {
    exitMIDlet();
  };

  public void exitMIDlet() {
    //取消任务
    timer.cancel();
    notifyDestroyed();
  };

  //生成一个非负的随机数
  private int genRandom(int upper) {
    return (Math.abs(random.nextInt()) % upper);
  };

  public Display getDisplay() {
    return display;
  };

  protected void initMIDlet() {
    try {
      AnimatedCanvas c = new AnimatedCanvas(getDisplay());
      Image[] images = loadFrames("/images/bird", BIRD_FRAMES);

      int w = c.getWidth();
      int h = c.getHeight();

      birds = new AnimatedImage[NUM_BIRDS];
      for (int i = 0; i < NUM_BIRDS; ++i) {
        AnimatedImage b = new AnimatedImage(c, images);
        birds[i] = b;
        b.move(genRandom(w), genRandom(h));
        c.add(b);
        timer.schedule(b, genRandom(1000), genRandom(400));
      }
      c.addCommand(exitCommand);
      c.setCommandListener(this);

      getDisplay().setCurrent(c);
    }
    catch (IOException e) {
      System.out.println("装入图像失败");
      exitMIDlet();
    }
  }

  //装入动画图像，图像以PNG格式存放
  private Image[] loadFrames(String name, int frames) throws IOException {
    Image[] images = new Image[frames];
    for (int i = 0; i < frames; ++i) {
      images[i] = Image.createImage(name + i + ".png");
    }
    return images;
  };

  protected void pauseApp() {
  };

  protected void startApp() throws MIDletStateChangeException {
    if (display == null) {
      display = Display.getDisplay(this);
      initMIDlet();
    }
  }
}