simplepong.java

java多媒体技术 7.1 播放声音文件 7.2 收音机 7.3 电子琴 7.4 吃豆游戏 7.5 简易壁球 7.6 弹球游戏 7.7 拯救生命 7.8 扫雷 7.9 双向飞碟 7

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.lang.Math;
import java.net.*;
import java.awt.image.*;

public class SimplePong extends Applet
{    
    public void init()
    {
	//设置默认值：颜色为黑色，宽度为300,高度为80
	//难度为5, 背景图为 backing.gif
	int bcRed = 0;
	int bcBlue = 0;
	int bcGreen = 0;
	int Width = 300;
	int Height = 80;
	int Difficulty = 5;
	String backimage = "backing.gif";
	//检测用户输入的参数值
	if(getParameter("Red")!=null)
	    bcRed = new Integer(getParameter("Red").trim()).intValue();
	if(getParameter("Blue")!=null)
	    bcBlue = new Integer(getParameter("Blue").trim()).intValue();
	if(getParameter("Green")!=null)
	    bcGreen = new Integer(getParameter("Green").trim()).intValue();
	if(getParameter("Width")!=null)
	    Width = new Integer(getParameter("Width").trim()).intValue() -20;
	if(getParameter("Height")!=null)
	    Height = new Integer(getParameter("Height").trim()).intValue()-20;
	if(getParameter("Difficulty")!=null)
	    Difficulty = new Integer(getParameter("Difficulty").trim()).intValue();
	if(getParameter("BackImage")!=null)
	    backimage= getParameter("BackImage");
	//设置参数
	setBackground(new Color(bcRed,bcGreen,bcBlue));
	Image ball = getImage(getCodeBase(), "ball.gif");
	Image paddle1 = getImage(getCodeBase(),"panel1.gif");
	Image paddle2 = getImage(getCodeBase(),"panel2.gif");
	Image back = getImage(getCodeBase(),backimage);
	Image toplay = getImage(getCodeBase(),"Toplay.gif");    
	//使用正确的参数值创建一个壁球平台
	PongTable pongtable = new PongTable(Width,Height,ball,paddle1,paddle2,back,toplay, Difficulty);
	setLayout(new BorderLayout());
	Panel centredpanel = new Panel();
	centredpanel.add(pongtable);
	add(centredpanel, "Center");
    }
}
//创建一个PongTable类
class PongTable extends Canvas implements Runnable, MouseMotionListener, MouseListener
{
    int Xsize, Ysize, Xball, Yball, Xbat, Ybat, XbatC, YbatC, difficulty;
    double direction[] = new double[2];
    Thread thisthread;
    int Xbatdir[] = new int[2];
    int Ybatdir[] = new int[2];
    boolean Centred = true;
    Image ball, paddle1, paddle2, back, toplay;
    //构造函数	
    PongTable(int xsize, int ysize, Image Ball, Image Paddle1, Image Paddle2, Image Back, Image Toplay, int Difficulty)
    {	
	//该方法对所有的变量进行设置
	Toolkit toolkit = Toolkit.getDefaultToolkit();
	addMouseMotionListener(this);
	addMouseListener(this);
	setSize(xsize,ysize);
	Xsize = xsize;
	Ysize = ysize;
	startpositions();
	Xball = (int)Xsize/2;
	Yball = (int)Ysize/2;
	direction[0] = 0;
	direction[1] = 0;	
	ball = Ball;
	paddle1 = Paddle1;
	paddle2 = Paddle2;
	back = Back;
	toplay = Toplay;
	difficulty = Difficulty;	
	//启动线程
	thisthread = new Thread(this);
	thisthread.start();	
    }
    
    void startpositions()
    {
	//指定开始位置
	Xball = 20;
	Yball = 20;
	Xbat = 20;
	Ybat = 40;
	XbatC = Xsize -20;
	YbatC = 40;
	direction[0] = 4.0; //X 速度向量
	direction[1] = 4.0; //Y 速度向量
    }

    public void update(Graphics g) 
    {
	//使用标准的双缓冲区技术更新数据
	Graphics offgraph;
	Image offscreen = null;
	Dimension d = getSize();
       	offscreen = createImage(d.width, d.height);
	offgraph = offscreen.getGraphics();
	offgraph.setColor(getBackground());
	offgraph.fillRect(0, 0, d.width, d.height);
	offgraph.setColor(getForeground());
	paint(offgraph);
	g.drawImage(offscreen, 0, 0, this);
	offscreen.flush();
    }
    
    public void paint(Graphics g)
    {
	//画背景图
	g.drawImage(back,5,5,Xsize-10,Ysize-10,this);
	//画用户的球拍
	g.drawImage(paddle1,XbatC-2,YbatC-10,this);
	//画计算机的球拍
	g.drawImage(paddle2,Xbat-2,Ybat-10,this);
	//画球
	g.drawImage(ball,Xball-5, Yball-5,this);
	//如果没有人开始击球，就显示"click to play"
	if(Centred)
	    g.drawImage(toplay,10, 10,this);
    }

    public void run()
    {
	double Xballdb, Yballdb;
	Xballdb = Xball;
	Yballdb = Yball;
	int n;
	while(true)
	    {
		//在每次repaint()方法中，4次检测球体是否碰撞到边界
		for(n=0;n<4;n++)
		    {
			//用速度/4来增加X & Y
			Xballdb = Xballdb + direction[0]/4;
			Yballdb = Yballdb + direction[1]/4;
			//如果有任何一方没有打中球体，就说明游戏结束
			if(Xballdb<10 || Xballdb>Xsize-10)
			    {
				Xballdb = Xsize/2;
				Yballdb = Ysize/2;
				direction[0] = 0;
				direction[1] = 0;
				Centred = true;
			    }
		
			//判断球体是否碰到上、下墙壁，如果发生碰撞，就将y调整为-y
			if(Yballdb<10 || Yballdb>Ysize-10)
			    {
				direction[1]=-1*direction[1];
			    }

			//判断球体是否被用户的球拍所碰到
			if(Xballdb>18 && Xballdb<27)//X 为球拍的厚度
			    //判断球体与球拍之间的y方向的距离小于10个象素
			    if(Math.abs(Yballdb-Ybat)<=10)
				{
				    //如果是，那么设x = -x + x为球拍运动的x方向速度 
				    //y = -y + y 为球拍运动的y方向速度
				    direction[0] = -1*direction[0]+(int)((Xbatdir[0]-Xbatdir[1])/8);
				    direction[1] = direction[1]+(int)((Ybatdir[0]-Ybatdir[1])/8);
				    //将球放置在球拍的前面
				    Xballdb=28;				    
				}
		
			//对计算机的球拍作同样的判断
			if(Xballdb<(Xsize-15) && Xballdb>(Xsize-22))
			    if(Math.abs(Yballdb-YbatC)<=10)
				{
				    //设x = -x - random .
				    direction[0] = -1*direction[0] + -1*Math.random();
				    //y = -y + random no proportional to x speed
				    //阻止球体向后运动，继续在相同的y方向上运动
				    direction[1] = direction[1] + (direction[0]/4)*Math.sin(Math.random()*2*Math.PI);
				    //将球放置在球拍的前面
				    Xballdb=Xsize-23;
				}
		    }
		
		//更新坐标值
		Xball = (int)Xballdb;
		Yball = (int)Yballdb;
		//实现计算机AI
		if(Xball>Xsize/2)
		    {
			//使用一个简单而实用的逻辑来控制球拍的运动：
			//首先判断球拍和球体不在同一高度；
			//然后在判断球体在球拍的上面还是下面
			//最后根据难度参数决定球拍向上或者向下移动的象素值
			if((Yball-YbatC)!=0)
			    YbatC = (Yball-YbatC)/(Math.abs(Yball-YbatC))*difficulty + YbatC;
		    }
		
		//重新调用paint()方法
		repaint();
		
		//让线程睡眠50 ms
		try
		    {
			thisthread.sleep(50);
		    }
	
		catch(Exception e)
		    {
			System.out.println("Error on sleep");
		    }

	    }
    }

    public void mouseMoved(MouseEvent e)
    {
	int x = e.getX();
	int y = e.getY();	
	//实现球拍与鼠标一起运动，
	if(y>15 && y<Ysize-10)
	    {
		Ybat = y;
		//设置球拍运动方向，以便用户可以影响球拍的运动方向
		Xbatdir[1] = Xbatdir[0];
		Ybatdir[1] = Ybatdir[0];
		Xbatdir[0] = x;
		Ybatdir[0] = y;
	    }
	
	repaint();
    }
    
    public void mouseDragged(MouseEvent e)
    {
    }

    public void mousePressed(MouseEvent e)
    {
    }

    public void mouseReleased(MouseEvent e)
    {
    }

    public void mouseClicked(MouseEvent e)
    {
	//检测是否开始新的游戏
	if(Centred)
	    {
		startpositions();
		Centred = false;
	    }
    }

     public void mouseEntered(MouseEvent e)
    {	
    }

     public void mouseExited(MouseEvent e)
    {
    }
}