moveballbykey.java

主要是对于JAVA的编程的基本语言 希望能够帮得上你。

package applet;

import java.applet.Applet;
import java.applet.AudioClip;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

public class MoveBallByKey extends Applet implements KeyListener{
	
	int BallDiameter;  //定义小球直径
	int StepLength;    //定义移动步长
	int x, y;  //定义小球坐标		
	AudioClip impactsound,music;
	
	public void init(){			
		impactsound=this.getAudioClip(this.getCodeBase(),"applet/ding.wav");
		music=this.getAudioClip(this.getCodeBase(),"applet/情义两心知.mid");
		music.play();
		music.loop();
		this.addKeyListener(this);	
	}	
	
	public void update(Graphics g){
		paint(g);  //不进行背景清除
	}
	
	public void paint(Graphics g){
		Image offImage=this.createImage(this.getWidth(),this.getHeight());
		Graphics offGraphics=offImage.getGraphics();
		offGraphics.setColor(Color.BLACK);
		offGraphics.drawString("小球坐标("+(int)x+", "+(int)y+")",10,10);
		//offGraphics.setColor(new Color((int)(Math.random()*256),(int)(Math.random()*256),(int)(Math.random()*256)));
		offGraphics.setColor(Color.RED);
		offGraphics.fillArc(x, y, BallDiameter, BallDiameter, 0, 360);
		
		g.drawImage(offImage,0,0,this);
	}
	
	public void start() {        
        x=(int) (Math.random()*this.getWidth()*0.8); //定义小球初始横坐标
		y=(int) (Math.random()*this.getHeight()*0.8);	//定义小球初始纵坐标        
        BallDiameter=30; //定义小球的直径
    	StepLength=2; //定义小球的移动步长
    }     

	public void keyPressed(KeyEvent e) {		
		switch(e.getKeyCode()){
		case 37: //按左方向键
			x=x-StepLength;
			break;
		case 38: //按上方向键
			y=y-StepLength;
			break;
		case 39://按右方向键
			x=x+StepLength;
			break;
		case 40://按下方向键
			y=y+StepLength;
			break;
		}
		
		if(x<0){ //碰左壁
			x=0;
			impactsound.play();
		}
		if(x>=this.getWidth()-BallDiameter){ //碰右壁
			x=this.getWidth()-BallDiameter;
			impactsound.play();
		}
		if(y<0){ //碰上壁
			y=0;
			impactsound.play();
		}
		if(y>=this.getHeight()-BallDiameter){ //碰下壁
			y=this.getHeight()-BallDiameter;
			impactsound.play();
		}		
		repaint();		
	}

	public void keyTyped(KeyEvent e) {		
		
	}

	public void keyReleased(KeyEvent e) {
		
	}
	
}