小球动态屏保

Java第一课，屏幕保护程序的制作。

1. 首先建立包ball，然后创建模板类BallModel，在此类中定义小球的属性。

BallModel类代码如下 :

package ball;

import java.awt.Color;
import java.awt.Graphics;

public class BallModel {
    int x,y,d,speed; //定义小球的x,y坐标，小球直径和速度
    Color c; 
    
    //构造方法
    public BallModel() {
        x=(int)(Math.random()*1920); //随机生成x坐标
        y=(int)(Math.random()*1080);  //随机生成y坐标
        d=(int)(Math.random()*50)+10; //小球直径
        speed=12-d/6; //球直径越小速度越快
        c=new Color((int)(Math.random()*256), (int)(Math.random()*256), (int)(Math.random()*256));  //随机生成小球颜色
    }
    
    //画出小球
    public void drawBall(Graphics g){
        g.setColor(c); 
        g.fillOval(x, y, d, d);
    }

}

2. 新建BallPanel类，用来画出和移动小球。

BallPanel类代码如下 :

package ball;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import javax.swing.JPanel;

public class BallPanel extends JPanel implements MouseMotionListener{
    /**
     * 
     */
    private static final long serialVersionUID = 5088665161758943179L;
    
    int[] dir=new int[200];  //小球路径数组    
    BallModel[] ba=new BallModel[200];  //小球对象数组
    
    public BallPanel (){
        for (int i = 0; i < ba.length; i++) {
            ba[i]=new BallModel();  //创建小球对象
            dir[i]=(int)(Math.random()*4+1);  //生成小球路径
        }
    }
            
    //画出小球
    @Override
    public void paint(Graphics g) {
        super.paint(g);
        setOpaque(false);
        for (int i = 0; i < ba.length; i++) {
            ba[i].drawBall(g);  //调用模板中画小球的方法
            
        }
        
    }
    
    //小球的移动轨迹控制
    public void moveBall(){
        new Thread(){
            public void run() {  //重写run方法
                super.run();
                while(true){
                    for (int i=0;i<ba.length;i++){  //循环所有小球
                        
                        //判断路径，增加值使小球前进
                        switch (dir[i]) {
                        case 1:{
                            ba[i].x+=ba[i].speed;
                            ba[i].y+=ba[i].speed;
                            break;
                        }case 2:{
                            ba[i].x-=ba[i].speed;
                            ba[i].y+=ba[i].speed;
                            break;
                        }case 3:{
                            ba[i].x-=ba[i].speed;
                            ba[i].y-=ba[i].speed;
                            break;
                        }case 4:{
                            ba[i].x+=ba[i].speed;
                            ba[i].y-=ba[i].speed;
                            break;
                        }default:
                            break;
                        }
                      
                        //判断边界值，改变小球路径
                        if(ba[i].x>1920 - ba[i].d){
                            if(dir[i]==1){dir[i]=2;}
                            if(dir[i]==4){dir[i]=3;}
                            ba[i].c=new Color((int)(Math.random()*256), (int)(Math.random()*256), (int)(Math.random()*256));
                        }
                        if(ba[i].x<0){
                            if(dir[i]==2){dir[i]=1;}
                            if(dir[i]==3){dir[i]=4;}
                            ba[i].c=new Color((int)(Math.random()*256), (int)(Math.random()*256), (int)(Math.random()*256));
                        }
                        if(ba[i].y>1080 - ba[i].d){
                            if(dir[i]==1){dir[i]=4;}
                            if(dir[i]==2){dir[i]=3;}
                            ba[i].c=new Color((int)(Math.random()*256), (int)(Math.random()*256), (int)(Math.random()*256));
                        }
                        if(ba[i].y<0){
                            if(dir[i]==4){dir[i]=1;}
                            if(dir[i]==3){dir[i]=2;}
                            ba[i].c=new Color((int)(Math.random()*256), (int)(Math.random()*256), (int)(Math.random()*256));
                        }                        
                    }
                    repaint(); //重画
                    try {
                        Thread.sleep(20); //休眠20毫秒
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            };
        }.start();
    }


    @Override
    public void mouseDragged(MouseEvent e) {
        System.exit(0); //退出
        
    }


    @Override
    public void mouseMoved(MouseEvent e) {
        
    }

}

3. 新建BallFrame类，创建屏保窗口，添加各组件。

package ball;

import javax.swing.JFrame;
import com.sun.awt.AWTUtilities;

public class BallFrame {

    public static void main(String[] args) throws InterruptedException {
        JFrame j=new JFrame();
        BallPanel b=new BallPanel();
        j.add(b);
        j.setSize(1920, 1080);
        j.setUndecorated(true);  //去边框
        j.setLocationRelativeTo(null);  //居中
        j.setDefaultCloseOperation(3);  //默认关闭
        AWTUtilities.setWindowOpaque(j, false);  //设置透明
        j.setVisible(true);  //设为可见
        b.moveBall();  //调用小球移动方法
        j.addMouseMotionListener(b); //注册监听器
    }

}

OK，一个简单的屏保程序就完成了。

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