Java 多线程小球实现

java 多线程的练习，实现一个线程控制一个小球，多个小球在面板上运动的效果，主要包括4个类：

• Ball类，用于保存一个小球的位置，实现移动小球的具体方法，返回小球的形状范围以便其他类使用这个形状来绘制小球。

• BallPanel类，用于管理所有的小球，继承自Jpanel 类，重写了paintComponent方法，给出了面板重新绘制的具体操作。

• BallThread类，用于管理单个小球的运动，线程的run方法主要操作是每过一定的时间就调用一下Ball 的move 方法，间隔很短，小球就好像运动的一样。

• BallRun类，这是图像面板类，也是主类，用于启动和退出程序，同时也可以添加若干小球线程加入到面板中。

实现的效果图如下：

代码如下：

package ball;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import java.util.Random;
class Ball{
    private Double x;
    private Double y;
    private Double speedx;
    private Double speedy;
    private Rectangle2D bounds;
    private Double radius;
    public Ball(Double[] postion,Rectangle2D bounds){
        this.x=postion[0];
        this.y=postion[1];
        this.bounds=bounds;
        this.speedx=1.0;
        this.speedy=1.0;
        this.radius=20.0;
    }
    public void move(){
        x+=speedx;
        y+=speedy;
        if(x<radius+bounds.getMinX()){
            x=bounds.getMinX()+radius;
            speedx=-speedx;
        }
        if(x+radius>=bounds.getMaxX()){
            x=bounds.getMaxX()-radius;
            speedx=-speedx;
        }
        if(y<radius+bounds.getMinX()){
            y=bounds.getMinY()+radius;
            speedy=-speedy;
        }
        if(y+radius>=bounds.getMaxY()){
            y=bounds.getMaxY()-radius;
            speedy=-speedy;
        }
    }
    public Ellipse2D shape(){
        return new Ellipse2D.Double(x,y,radius,radius);
    }
}
class BallPanel extends JPanel{
    private ArrayList<Ball> balls;
    public BallPanel(){
        this.balls=new ArrayList<Ball>();
        this.setSize(1000,960);
    }
    public void add(Ball ball){
        this.balls.add(ball);
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D graphics2D=(Graphics2D) g;
        for(Ball ball:balls){
            graphics2D.fill(ball.shape());
        }
    }
}
class BallThread extends Thread{
    private Ball ball;
    private BallPanel ballPanel;
    private static Integer steps=4000;
    public BallThread(Ball ball,BallPanel ballPanel){
        this.ball=ball;
        this.ballPanel=ballPanel;
    }
    @Override
    public void run() {
        for(int i=0;i<steps;i++){
            ball.move();
            ballPanel.repaint();
            try {
                Thread.sleep(5);
            }catch (Exception e){}
        }
    }
}
public class BallRun {
    private JFrame frame;
    private BallPanel ballPanel;
    private Double[] RandomPostion(){
        Random random=new Random();
        Double[] position=new Double[2];
        position[0]=1000*random.nextDouble();
        position[1]=1000*random.nextDouble();
        return position;
    }
    public BallRun(){
        this.frame=new JFrame("多线程小球");
        frame.setSize(1000,1000);
        ballPanel=new BallPanel();
        JPanel buttonPanel=new JPanel();
        JButton addBall=new JButton("添加");
        JButton exitBtn=new JButton("退出");
        addBall.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                Ball ball=new Ball(RandomPostion(),ballPanel.getBounds());
                ballPanel.add(ball);
                BallThread thread=new BallThread(ball,ballPanel);
                thread.start();
            }
        });
        exitBtn.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                System.exit(0);
            }
        });
        buttonPanel.add(addBall);
        buttonPanel.add(exitBtn);
        frame.add(buttonPanel,BorderLayout.SOUTH);
        frame.add(ballPanel,BorderLayout.CENTER);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        BallRun ballRun=new BallRun();
    }
}