用JAVA实现雷电小游戏

效果图如下：

实现雷电小游戏，主要创建了三个类：Ball类、BallJPanel类、BallJFrame类

Ball类中定义了敌方战机、子弹和我方子弹，将该三者都看成圆，即看成同一个类
Ball类中包含dr()<画出敌机及其子弹>、mv()<敌机及其子弹的移动>、isTouch()<判断子弹之间是否碰撞>方法

public class Ball {
    int x,y;//圆角坐标
    int r;
    int ori;//方向 4向上 5向下
    int type;//标记类型，0我方发出，1敌方发出
    //awt包中Swing界面能识别图片的类
    public static Image image_fire =
            new ImageIcon("fire.gif").getImage();
    public static Image image_el =
            new ImageIcon("el_0.gif").getImage();
    //构造器
    public Ball(){

    }
    public Ball(int x, int y, int r, int ori, int type){
        this.x = x;
        this.y = y;
        this.r = r;
        this.ori = ori;
        this.type = type;
    }
    //画在相应的JPanel中
    public void dr(Graphics g){
        switch (type){
            case 0:
                g.drawImage(image_fire,x,y,
                        2*r,2*r,null);
                break;
            case 1:
                g.drawImage(image_el,x,y,
                        2*r,2*r,null);
                break;
        }
    }
    //判断两个球是否相遇
    public boolean isTouch(Ball ball2){
        boolean isTouch = false;
        //第一个圆心坐标
        int x1 = x + r;
        int y1 = y + r;
        //b2圆心坐标
        int x2 = ball2.x + ball2.r;
        int y2 = ball2.y + ball2.r;
        double s = Math.sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
        if (s<=r+ball2.r){
            isTouch = true;
        }
        return isTouch;
    }
    //我方子弹或敌机及其子弹移动
    public void mv(){
        switch (ori){
            case 4: y--;break;
            case 5: y++;break;
        }
    }
}

BallJPanel类中定义了画笔类、鼠标事件、监听器、多线程、我方飞机类等

/**
 * @author threee
 * @date 2020/2/14 - 13:20
 * 单继承 多实现
 * MouseMotionListener拖动，移动事件
 * MouseListener鼠标点击事件
 */
public class BallJPanel extends JPanel
        implements MouseListener, MouseMotionListener,Runnable {
    //我方子弹集合
    ArrayList<Ball> allBalls;
    //敌方子弹飞机集合
    ArrayList<Ball> allSnows;
    //是否开火，true开火
    boolean isFire;
    //积分
    int score;
    //我方飞机图片
    Image hero_img = new ImageIcon("hero.gif").getImage();
    //监听：随时准备好，等待事件的触发，一旦触发，相应的方法会发生效果
    //监听代码放在构造器中，表示BallJPanel一初始化就可监听了
    public BallJPanel(){
        //第一个this代表当前BallJPanel
        //第二个this代表当前鼠标事件
        this.addMouseListener(this);
        this.addMouseMotionListener(this);
        //我方飞机默认出现的位置
        plane.x = 100;
        plane.y = 400;
        //得分默认为0
        score = 0;
        allBalls = new ArrayList<>();
        allSnows = new ArrayList<>();
    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);
        //显示背景图
        //通过当前类所有的目录取路径
        URL imgURL = getClass().getResource("back.jpg");
        ImageIcon icon = new ImageIcon(imgURL);
        //放入图片
        g.drawImage(icon.getImage(),0,0,400,600,this);
        //我方飞机
        g.drawImage(hero_img,plane.x,plane.y,200,100,null);
        //积分
        g.setColor(Color.red);
        g.setFont(new Font("宋体",Font.BOLD,24));
        g.drawString("积分",300,35);
        g.drawString(String.valueOf(score),350,35);
        g.drawString("生命",300,60);
        g.drawString(String.valueOf(plane.life),350,60);
        //假设allBalls有Ball时，每个ball要画出来
        for (int i=0;i<allBalls.size(); i++){
            Ball b = allBalls.get(i);
            b.dr(g);
        }
        for (int i=0;i<allSnows.size(); i++){
            Ball b = allSnows.get(i);
            b.dr(g);
        }
    }
    //线程需要做的事
    @Override
    public void run() {
        //判断isFire是否为true
        int count = 0;
        while(true){
            //通过count控制频率
            count++;
            if (count>=Integer.MAX_VALUE){
                count = 0;
            }
            //不断落下的敌机
            if(count%60 == 0){
                Ball b = new Ball((int)(Math.random()*400),
                        -50,30,5,1);
                allSnows.add(b);
            }
            //敌方飞机子弹下移
            for (int i=0; i<allSnows.size(); i++){
                Ball b1 = allSnows.get(i);
                b1.mv();
                if (b1.y>600){
                    allSnows.remove(b1);
                }
            }
            //判断isFire是否为true
            if (isFire && count%100 == 0){
                Ball ball1 = new Ball(plane.x+100,plane.y+50,20,4,0);
                allBalls.add(ball1);
            }
            //我方子弹上移
            for (int i=0; i<allBalls.size(); i++){
                Ball b2 = allBalls.get(i);
                b2.mv();
                if (b2.y<0){
                    allBalls.remove(b2);
                }
            }
            //当我方子弹遇到敌机时，双方都消失，积分 +10
            for (int i=0; i<allBalls.size(); i++){
                for (int j=0; j<allSnows.size(); j++){
                    if ( i<allBalls.size() && j<allSnows.size()
                    && allBalls.get(i).isTouch(allSnows.get(j))){
                        allBalls.remove(i);
                        allSnows.remove(j);
                        score += 10;
                    }
                }
            }
            //我方战机碰撞敌方战机时，生命 -10
            for (int i=0; i<allSnows.size(); i++){
                if (i<allSnows.size() && plane.isCrash(allSnows.get(i))){
                    plane.life -= 10;
                    allSnows.remove(i);
                    if(plane.life <= 0){
                        plane.die = true;
                        //弹出信息提示框
                        JOptionPane.showMessageDialog(null,"GAME OVER！");
                    }
                }
            }
            if (plane.die){
                System.exit(0);
            }
            try {
                Thread.sleep(20);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            repaint();
        }
    }
    @Override
    public void mouseClicked(MouseEvent e) {

    }

    @Override
    public void mousePressed(MouseEvent e) {
        isFire = true;
    }

    @Override
    public void mouseReleased(MouseEvent e) {
        isFire = false;
    }

    @Override
    public void mouseEntered(MouseEvent e) {

    }

    @Override
    public void mouseExited(MouseEvent e) {

    }

    @Override
    //拖动
    public void mouseDragged(MouseEvent e) {
        //e是鼠标的实时位置
        plane.x = e.getX()-100;
        plane.y = e.getY()-50;
        repaint();
    }

    @Override
    public void mouseMoved(MouseEvent e) {
        //e是鼠标的实时位置
//        x = e.getX();
//        y = e.getY();
//        repaint();
    }
}
class plane{
    //我方飞机坐标
    static int x,y;
    //我方飞机生命值
    static int life = 100;
    //飞机是否死亡
    static boolean die = false;
    public static boolean isCrash(Ball ball2){
        boolean isCrash = false;
        int x1 = plane.x + 100;
        int y1 = plane.y + 50;
        int x2 = ball2.x + ball2.r;
        int y2 = ball2.y + ball2.r;
        double s = Math.sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
        if (s<=30+ball2.r){
            isCrash = true;
        }
        return isCrash;
    }
}

BallJFrame类中定义了主窗体，main方法。用sh()方法画出界面，构造器运行线程

public class BallJFrame extends JFrame {
    BallJPanel jPanel;
    public BallJFrame(){
        jPanel = new BallJPanel();
        this.add(jPanel);
        Thread thread = new Thread(jPanel);
        thread.start();
    }
    //写一个方法画出界面
    public void sh(){
        this.setSize(400,600);
        this.setTitle("雷电");
        //当点击JFrame关闭时，整个程序也随之关闭
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);
    }
    public static void main(String[] args) {
        BallJFrame jFrame = new BallJFrame();
        jFrame.sh();
    }
}

本次实践知识总结：

把图片放入窗体中有两种方法:
(1)、通过URL查找当前类的目录路径，再赋给ImageIcon类的对象，再用画笔类drawImage方法画出（图片放在当前类的同一个包下）

//通过当前类所有的目录取路径
       URL imgURL = getClass().getResource("back.jpg");
       ImageIcon icon = new ImageIcon(imgURL);
       //放入图片
       g.drawImage(icon.getImage(),0,0,400,600,this);

（2）、直接new一个ImageIcon类的对象赋给Image类的对象，再用画笔类drawImage方法画出（图片放在项目的根目录下）

//awt包中Swing界面能识别图片的类
    public static Image image_fire =
            new ImageIcon("fire.gif").getImage();
    public static Image image_el =
            new ImageIcon("el_0.gif").getImage();
            g.drawImage(image_fire,x,y,
                        2*r,2*r,null);
            g.drawImage(image_el,x,y,
                        2*r,2*r,null);

java中添加信息弹出框的方法：

1	JOptionPane.showMessageDialog(null,"GAME OVER！");