坦克大战一：我方坦克

1、锁synchronized

public class Good extends Thread {
    private static int num = 10;

    @Override
    public void run() {
        while (num > 1) {
            try {
                Thread.sleep(1000);
                buyOne();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    private void buyOne() {
            num--;
            System.out.println(getName() + ",剩余数量：" + num);
    }
}

以上为一个商品类，数量为10，每次执行buyOne就会买走一个商品。正常情况下只有当商品数量大于0时，才能买走商品，但是如果有两个线程同时访问该方法 就会出现两个人买到同一件商品。甚至出现商品数量为负数的情况，所以为了避免出现这种情况，给相应的方法加上锁

private static final Object OBJ = new Object();
private void buyOne() {
        synchronized (OBJ) {
            num--;
            System.out.println(getName() + ",剩余数量：" + num);
        }
    }

2、坦克四向运动

绘制四个方向的坦克图片置于panel中，四张图片文件名最后一位通过字母的d，s，a，w来区分。这样方便后面控制坦克移动，接下来是实现代码和简单解释

/*
为了方便后期的阅读和升级，这里将地图上的各个精灵（包括地图）分别封装到不同的类中
*/
import com.woniu.javaweek04.javaday23.tank_game.model.MyMap;
import com.woniu.javaweek04.javaday23.tank_game.model.MyTank;

import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

public class StagePanel extends JPanel implements Runnable, KeyListener {
    private MyMap myMap = new MyMap();
    private MyTank myTank = new MyTank();

    @Override
    public void run() {
        while (true) {
            gameUpdate();
            try {
                Thread.sleep(6);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            repaint();//坐标改变后重新绘制图片
        }
    }

    private void gameUpdate() {
        myTank.update();
    }

    @Override
    public void paint(Graphics g) {
        myMap.setG(g);
        myMap.setStage(this);
        myMap.show();
        myTank.setG(g);
        myTank.setStage(this);
        myTank.show();
    }


    @Override
    public void keyTyped(KeyEvent e) {

    }

    @Override
    public void keyPressed(KeyEvent e) {//键盘按压监听
        int key = e.getExtendedKeyCode();
        //以下四个分支分别代表长按dsaw或上右下左上，可以操控坦克的移动
        //将我方坦克的cmd设置为对应字符
        if (key == 39 || key == 68) {
            myTank.cmd = "dd";
        } else if (key == 40 || key == 83) {
            myTank.cmd = "ss";
        } else if (key == 37 || key == 65) {
            myTank.cmd = "aa";
        } else if (key == 38 || key == 87) {
            myTank.cmd = "ww";
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {//键盘释放监听
        int key = e.getExtendedKeyCode();
        //以下四个分支分别代表从dsaw或上右下左上松开
        if (key == 39 || key == 68) {
            myTank.cmd = "d";
        } else if (key == 40 || key == 83) {
            myTank.cmd = "s";
        } else if (key == 37 || key == 65) {
            myTank.cmd = "a";
        } else if (key == 38 || key == 87) {
            myTank.cmd = "w";
        }
    }
}

以下是目前实现好的我方坦克类

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.io.File;
import java.io.IOException;

public class MyTank {
    private Graphics g;
    private JPanel stage;
    private int x = 0;
    private int y = 0;
    public String cmd = "d";

    public Graphics getG() {
        return g;
    }

    public void setG(Graphics g) {
        this.g = g;
    }

    public JPanel getStage() {
        return stage;
    }

    public void setStage(JPanel stage) {
        this.stage = stage;
    }

    public void show() {
        Image img = null;
        try {
            img = ImageIO.read(new File("staticTank/mytank-" + cmd.substring(0, 1) + ".png"));//不论是cmd是一个字符还是两个字符，都能使得坦克朝向正确的方向
        } catch (IOException e) {
            e.printStackTrace();
        }
        g.drawImage(img, x, y, 64, 64, stage);
    }

    public void update() {
        //StagePanel通过监听键盘获得坦克对应的字符
        //根据对应字符控制x，y数值的加减，实现坦克的坐标变化，以此达到移动的效果
        if ("dd".equals(cmd)) {
            x++;
        } else if ("ss".equals(cmd)) {
            y++;
        } else if ("aa".equals(cmd)) {
            x--;
        } else if ("ww".equals(cmd)) {
            y--;
        }
    }
}