spritedemo.java

人民邮电出版社的《J2ME手机开发入门》全部源代码

/*
 * SpriteDemo.java
 *
 * Created on 2005年5月2日, 下午12:14
 */

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

import javax.microedition.lcdui.game.*;

/**
 *
 * @author  Liu Bin
 * @version
 */
public class SpriteDemo extends MIDlet  implements CommandListener {
    Display display = null;
    private Command cmdExit = new Command("Exit", Command.STOP, 1);
    
    private SpriteDemoCanvas can = null;
    
    public SpriteDemo() {
        display = Display.getDisplay(this);
        can = new SpriteDemoCanvas(false);
        can.addCommand(cmdExit);
        can.setCommandListener(this);
    }
    
    public void startApp() throws MIDletStateChangeException {
        display.setCurrent(can);
        can.startgame();
    }
    
    public void pauseApp() {
    }
    
    public void destroyApp(boolean unconditional) {
        can.gameover();
    }
    
    /**
     * 命令按钮事件
     */
    public void commandAction(Command c, Displayable d) {
        if (c == cmdExit) {
            notifyDestroyed();
        }
    }
}

class SpriteDemoCanvas extends GameCanvas implements Runnable{
    //游戏结束标志
    private boolean gameover = false;
    //龙的死亡标志
    private boolean dead = false;
    
    //定义动画的dragon和非动画的missile精灵
    private Sprite dragon, missile;
    
    //游戏背景图像
    private Image imgMissile, imgBG;
    //后台缓冲屏幕宽和高
    private int canW, canH;
    
    //导弹的移动方向，缺省为向右
    private int direction = RIGHT;
    //导弹的移动速度，缺省值为10
    private int speed = 10;
    //帧的宽度和高度
    private static final int DRAGON_FRAME_WIDTH = 48;
    private static final int DRAGON_FRAME_HEIGHT = 48;
    //动画顺序
    int[] dragonAnimationSequence = {2,3,4,5,3,4,5,4};
    
    public SpriteDemoCanvas(boolean suppressKeyEvents) {
        super(suppressKeyEvents);
        //计算游戏中使用的一些值
        canW =  getWidth();
        canH = getHeight();
        out("画布的宽度：" + canW);
        out("画布的高度：" + canH);
        
        //装载游戏图像
        try {
            missile = new Sprite(
                    Image.createImage("/Res/Missile.png"));
            missile.setPosition(canW/2, canH/2);
            out("装载导弹图像...成功");
            
            dragon = new Sprite(
                    Image.createImage("/Res/dragon.png"),
                    DRAGON_FRAME_WIDTH,
                    DRAGON_FRAME_HEIGHT);
            dragon.setFrameSequence(dragonAnimationSequence);
            out("装载背景图像...成功");
            
            imgBG = Image.createImage("/Res/BG.png");
            out("装载背景图像...成功");
        } catch (Exception e) {
            out("装载游戏图像异常：" + e.toString());
        }
    }
    
    //清除屏幕
    private void clearScreen(Graphics g) {
        g.setColor(0xFFFFFF);
        g.fillRect(0, 0, canW, canH);
        g.setColor(0x000000);
        //绘制背景图像
        if (imgBG != null) {
            g.drawImage(imgBG, 0, 0, Graphics.TOP | Graphics.LEFT);
        }
    }
    
    //当用户按下0-9键时调整火箭的运行速度
    protected void keyReleased(int keyCode) {
        //有些手机实现中数字键2,4,6,8可能会被映射为up, left, right and down键，
        //因此这里通过键值调整运行速度
        if (keyCode >= KEY_NUM1 && keyCode <= KEY_NUM9) {
            speed = (keyCode - KEY_NUM0)*5;
            out("游戏速度调整为：" + speed);
        }
    }
    
    //输出调试信息
    private void out(String msg) {
        System.out.println(msg);
    }
    
    public void run() {
        //获得后台缓冲屏幕
        Graphics g = getGraphics();
        
        while (!gameover) {
            clearScreen(g);

            if (!dead) {
                //根据按钮移动导弹
                int keyState = getKeyStates();
                if ((keyState & LEFT_PRESSED) != 0) {
                    move(-speed, 0);
                } else if ((keyState & RIGHT_PRESSED) != 0) {
                    move(speed, 0);
                } else if ((keyState & UP_PRESSED) != 0) {
                    move(0, -speed);
                } else if ((keyState & DOWN_PRESSED) != 0) {
                    move(0, speed);
                }
                
                //绘制游戏屏幕
                gameRender(g);
            } else {
                gameoverAnimation(g);
            }
            
            //绘制后台缓冲屏幕
            flushGraphics();
            
            try {
                Thread.sleep(100); //暂停一段时间
            } catch(InterruptedException ex){
            }
        }
    }
    
    private void gameoverAnimation(Graphics g) {
        int[] ds = {0};
        dragon.setFrameSequence(ds);
        if (dragon.getY() < canH) {
            dragon.setPosition(dragon.getX(),
                    dragon.getY() + speed);
            dragon.paint(g);
        } else {
            String str = "游戏结束";
            g.setColor(255,0,0);
            Font f = Font.getFont(Font.FACE_SYSTEM,
                    Font.STYLE_BOLD,
                    Font.SIZE_LARGE);
            g.drawString(str, (canW - f.stringWidth(str))/2,
                    canH/2,
                    Graphics.TOP | Graphics.LEFT);
            gameover = true;
        }
    }
    
    //移动导弹
    private void move(int dx, int dy) {
        dragon.move(dx,dy);
        //碰撞检测
        dead = dragon.collidesWith(missile, true);
    }
    
    private void gameRender(Graphics g) {
        missile.paint(g);
        dragon.nextFrame();
        dragon.paint(g);
    }
    
    //结束游戏
    public void gameover() {
        gameover = true;
    }
    
    //开始游戏
    public void startgame() {
        //初始化...
        gameover = false;
        //开始游戏线程
        new Thread(this).start();
    }
}