ballapplet.java

Java程序设计实用教程源代码 本书源代码按章分别放置在不同的文件夹中,所有程序均在JDK1.6环境下编译运行正常,除了第13章需要建立ODBC数据源之外,其他程序只要有Java运行环境即可直接运行

import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;

public class ballApplet extends Applet implements Runnable {
  Dimension d;
  Font bFont = new Font("Helvetica", Font.BOLD, 24);
  Font sFont = new Font("Helvetica", Font.BOLD, 14);
  FontMetrics fmSmall, fmBig;
  Graphics goff;
  Image img;
  Thread mThread;
  boolean ingame = false;
  int ballx, bally;        //球的坐标
  int batpos;              //球拍的位置x坐标
  int batdpos = 0;         //球拍的便宜量
  int balldx = 0, balldy = 0,dxval;
  int iScroe,ballNum;      //分数和球的数量
  boolean[] showbrick;
  int brickNumOfLine;      //每行的砖块数
  final int bWidth = 5;    //border宽度
  final int batW = 20;     //球拍的宽度
  final int ballsize = 5;  //球拍的大小
  final int batH = 5;      //球拍的高度
  final int scoreH = 25;   //显示分数的相对高度
  final int brickW = 15;   //砖块的宽度
  final int brickH = 8;    //砖块的高度
  final int space = 1;     //砖块间的间隔
  final int backcol = 0x102010;//背景色
  final int line = 4;      //砖块总行数
  final int startline = 32;

  public void init() {
    Graphics g;
    d = size();
    setBackground(new Color(backcol));
    brickNumOfLine = (d.width - 2 * bWidth) / (brickW + space);
    d.width = brickNumOfLine * (brickW + space) + (2 * bWidth);
    g = getGraphics();
    g.setFont(sFont);
    fmSmall = g.getFontMetrics();
    g.setFont(bFont);
    fmBig = g.getFontMetrics();
    showbrick = new boolean[brickNumOfLine * line];
    GameInit();
  }
  public void GameInit() {
    batpos = (d.width - batW) / 2;
    ballx = (d.width - ballsize) / 2;
    bally = (d.height - ballsize - scoreH - 2 * bWidth);
    iScroe = 0;
    ballNum = 3;
    dxval = 2;
    if (Math.random() < 0.5)
      balldx = dxval;
    else
      balldx = -dxval;
    balldy = -dxval;
    batdpos = 0;
    InitBricks();
  }
  public void InitBricks() {
    int i;
    for (i = 0; i < line * brickNumOfLine; i++)
      showbrick[i] = true;
  }
  public boolean keyDown(Event e, int key) {
    if (ingame) {
      if (key == Event.LEFT)
        batdpos = -4;
      if (key == Event.RIGHT)
        batdpos = 4;
      if (key == Event.ESCAPE)
        ingame = false;
    }
    else {
      if (key == 's' || key == 'S') {
        ingame = true;
        GameInit();
      }
    }
    return true;
  }
  public boolean keyUp(Event e, int key) {
    if (key == Event.LEFT || key == Event.RIGHT)
      batdpos = 0;
    return true;
  }
  public void paint(Graphics g) {
    if (goff == null && d.width > 0 && d.height > 0) {
      img = createImage(d.width, d.height);
      goff = img.getGraphics();
    }
    if (goff == null || img == null)
      return;
    goff.setColor(new Color(backcol));
    goff.fillRect(0, 0, d.width, d.height);
    if (ingame)
      PlayGame();
    else
      ShowIntroScreen();
    g.drawImage(img, 0, 0, this);
  }
  public void PlayGame() {
    MoveBall();
    CheckBat();
    CheckBricks();
    DrawPlayField();
    DrawBricks();
    ShowScore();
  }
  public void ShowIntroScreen() {
    MoveBall();
    CheckBat();
    CheckBricks();
    BatDummyMove();
    DrawPlayField();
    DrawBricks();
    ShowScore();
    goff.setFont(bFont);
    goff.setColor(new Color(96, 128, 255));
    String s = "弹球游戏";
    goff.drawString(s, (d.width - fmBig.stringWidth(s)) / 2,
                    (d.height - scoreH - bWidth) / 2 - 20);
    goff.setFont(sFont);
    goff.setColor(new Color(128, 255, 32));
    s = "请按下'S'键开始游戏！";
    goff.drawString(s, (d.width - fmSmall.stringWidth(s)) / 2,
                    (d.height - scoreH - bWidth) / 2 + 30);
    goff.setColor(new Color(255, 160, 64));
    s = "请使用方向键来控制球拍的运动";
    goff.drawString(s, (d.width - fmSmall.stringWidth(s)) / 2,
                    (d.height - scoreH - bWidth) / 2 + 50);
  }
  public void DrawBricks() {
    int i, j;
    boolean nobricks = true;
    int colorDelta = 255 / (line - 1);
    for (j = 0; j < line; j++) {
      for (i = 0; i < brickNumOfLine; i++) {
        if (showbrick[j * brickNumOfLine + i]) {
          nobricks = false;
          goff.setColor(new Color(255, j * colorDelta, 255 - j * colorDelta));
          goff.fillRect(bWidth + i * (brickW + space),
                        startline + j * (brickH + space),brickW, brickH);
        }
      }
    }
    if (nobricks) {
      InitBricks();
      if (ingame)
        iScroe += 100;
    }
  }
  public void DrawPlayField() {
    goff.setColor(Color.white);
    goff.fillRect(0, 0, d.width, bWidth);
    goff.fillRect(0, 0, bWidth, d.height);
    goff.fillRect(d.width - bWidth, 0, bWidth, d.height);
    goff.fillRect(0,d.height - bWidth, d.width, bWidth);
    goff.fillRect(batpos, d.height - 2 * bWidth - scoreH, batW,batH); // 球拍
    goff.fillRect(ballx, bally, ballsize, ballsize); // 球
  }
  public void ShowScore() {
    goff.setFont(sFont);
    goff.setColor(Color.white);
    goff.drawString("得分: " + iScroe, 40, d.height - 10);
    String s = "生命数量: " + ballNum;
    goff.drawString(s, d.width - 40 - fmSmall.stringWidth(s), d.height - 10);
  }
  public void MoveBall() {
    ballx += balldx;
    bally += balldy;
    if (bally <= bWidth) {
      balldy = -balldy;
      bally = bWidth;
    }
    if (bally >= (d.height - ballsize - scoreH)) {
      if (ingame) {
        ballNum--;
        if (ballNum <= 0)
          ingame = false; //游戏结束
      }
      ballx = batpos + (batW - ballsize) / 2;
      bally = startline + line * (brickH + space);
      balldy = dxval;
      balldx = 0;
    }
    if (ballx >= (d.width - bWidth - ballsize)) {
      balldx = -balldx;
      ballx = d.width - bWidth - ballsize;
    }
    if (ballx <= bWidth) {
      balldx = -balldx;
      ballx = bWidth;
    }
  }
  public void BatDummyMove() {
    if (ballx < (batpos + 2))
      batpos -= 3;
    else if (ballx > (batpos + batW - 3))
      batpos += 3;
  }
  public void CheckBat() {
    batpos += batdpos;
    if (batpos < bWidth)
      batpos = bWidth;
    else if (batpos > (d.width - bWidth - batW))
      batpos = (d.width - bWidth - batW);

    if (bally >= (d.height - scoreH - 2 * bWidth - ballsize) &&
        bally < (d.height - scoreH - 2 * bWidth) &&
        (ballx + ballsize) >= batpos && ballx <= (batpos + batW)) {
      bally = d.height - scoreH - ballsize - bWidth * 2;
      balldy = -dxval;
      balldx = CheckBatBounce(balldx, ballx - batpos);
    }
  }
  public int CheckBatBounce(int dy, int delta) {
    int sign;
    int stepsize, i = -ballsize, j = 0;
    stepsize = (ballsize + batW) / 8;
    if (dy > 0)
      sign = 1;
    else
      sign = -1;
    while (i < batW && delta > i) {
      i += stepsize;
      j++;
    }
    switch (j) {
      case 0:
      case 1:
        return -4;
      case 2:
        return -3;
      case 7:
        return 3;
      case 3:
      case 6:
        return sign * 2;
      case 4:
      case 5:
        return sign * 1;
      default:
        return 4;
    }
  }
  public void CheckBricks() {
    int i, j, x, y;
    int xspeed = balldx;
    if (xspeed < 0)
      xspeed = -xspeed;
    int ydir = balldy;
    if (bally < (startline - ballsize) ||
        bally > (startline + line * (space + brickH)))
      return;
    for (j = 0; j < line; j++) {
      for (i = 0; i < brickNumOfLine; i++) {
        if (showbrick[j * brickNumOfLine + i]) {
          y = startline + j * (space + brickH);
          x = bWidth + i * (space + brickW);
          if (bally >= (y - ballsize) && bally < (y + brickH) &&
              ballx >= (x - ballsize) && ballx < (x + brickW)) {
            showbrick[j * brickNumOfLine + i] = false;
            if (ingame)
              iScroe += (line - j);
            // 敲击砖块的地点
            if (ballx >= (x - ballsize) && ballx <= (x - ballsize + 3)){
              balldx = -xspeed;
            }
            else if (ballx <= (x + brickW - 1) && ballx >= (x + brickW - 4)){
              balldx = xspeed;
            }
            balldy = -ydir;
          }
        }
      }
    }
  }
  public void run() {
    long starttime;
    Graphics g = getGraphics();
    Thread.currentThread().setPriority(Thread.MAX_PRIORITY);
    while (true) {
      starttime = System.currentTimeMillis();
      try {
        paint(g);
        starttime += 20;
        Thread.sleep(Math.max(0, starttime - System.currentTimeMillis()));
      }
      catch (InterruptedException e) {
        break;
      }
    }
  }
  public void start() {
    if (mThread == null) {
      mThread = new Thread(this);
      mThread.start();
    }
  }
  public void stop() {
    if (mThread != null) {
      mThread.stop();
      mThread = null;
    }
  }
  public static void main(String[] args) {
    Frame frame = new Frame("弹球游戏");
    ballApplet app = new ballApplet();
    frame.add("Center", app);
    frame.setSize(270, 350);
    frame.validate();
    frame.setVisible(true);
    frame.addWindowListener(new WindowControl(app));
    app.init();
    app.start();
  }
}
class WindowControl extends WindowAdapter {
  Applet app;
  public WindowControl(Applet app) {
    this.app = app;
  }
  public void windowClosing(WindowEvent e) {
  	app.stop();
    app.destroy();
    System.exit(0);
  }
}