JAVA-GUI编程入门，一小时开发贪吃蛇游戏。
开发环境：JDK1.8.0_131、IEDA
用到的知识点：JFrame、JPanel、KeyListener、ActionListener、Graphics、ImageIcon、Timer、数组
基本功能：按下空格键开始游戏，小蛇吃一个食物加一分，碰到边界或者自己身体游戏结束，再按下空格键继续游戏。
素材来自：https://www.iconfont.cn

游戏概况

1.新建JAVA项目

2.src目录下新建statics文件夹，存放素材文件

3.话不多说，直接上代码

3.1新建启动类StartGame.java

public class StartGame {

public static void main(String[] args) {
    JFrame frame = new JFrame();

    frame.setTitle("贪吃蛇");
    frame.setBounds(100, 100, 500, 432);
    frame.setResizable(false);
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

    frame.add(new GamePanel());

    frame.setVisible(true);

}

}
因为我的图片素材为20×20，所以fram的大小我定义为500×432。

3.2新建素材类Data.java

包含小蛇的头、蛇体、食物。
public class Data {

// public static URL headerURL = Data.class.getResource(“statics/header.png”);
// public static ImageIcon header = new ImageIcon(headerURL);

public static URL upURL = Data.class.getResource("statics/up.png");
public static URL downURL = Data.class.getResource("statics/down.png");
public static URL leftURL = Data.class.getResource("statics/left.png");
public static URL rightURL = Data.class.getResource("statics/right.png");
public static ImageIcon up = new ImageIcon(upURL);
public static ImageIcon down = new ImageIcon(downURL);
public static ImageIcon left = new ImageIcon(leftURL);
public static ImageIcon right = new ImageIcon(rightURL);

public static URL bodyURL = Data.class.getResource("statics/body.png");
public static ImageIcon body = new ImageIcon(bodyURL);

public static URL foodURL = Data.class.getResource("statics/food.png");
public static ImageIcon food = new ImageIcon(foodURL);

}

3.3新建小蛇控制类GamePanel.java

public class GamePanel extends JPanel implements KeyListener, ActionListener {

int length;
int[] snakeX = new int[200];
int[] snakeY = new int[200];
String fx;
boolean isStart = false;
boolean isFail = false;

int foodX,foodY;
Random random = new Random();

int score;

Timer timer = new Timer(100, this);

public GamePanel() {
    init();
    this.setFocusable(true);
    this.addKeyListener(this);
    this.timer.start();
}

public void init() {
    fx = "R";
    score = 0;

    length = 3;
    snakeX[0] = 40;snakeY[0] = 50;
    snakeX[1] = 20;snakeY[1] = 50;
    snakeX[2] = 0;snakeY[2] = 50;

    foodX = 0 + 20*random.nextInt(10);
    foodY = 50 + 20*random.nextInt(10);
}


@Override
protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    this.setBackground(Color.white);
    g.setColor(Color.decode("#DCDCDC"));
    g.fillRect(0,50, 500, 360);
    g.setColor(Color.white);
    for (int i = 1; i < 18; i++) {
        g.drawLine(0,50+i*20,525,50+i*20);
    }
    for (int i = 1; i < 25; i++) {
        g.drawLine(i*20,50,i*20,410);
    }

    Data.food.paintIcon(this,g,foodX,foodY);

    if (fx.equals("R")) {
        Data.right.paintIcon(this,g,snakeX[0],snakeY[0]);
    } else if (fx.equals("L")) {
        Data.left.paintIcon(this,g,snakeX[0],snakeY[0]);
    } else if (fx.equals("U")) {
        Data.up.paintIcon(this,g,snakeX[0],snakeY[0]);
    } else if (fx.equals("D")) {
        Data.down.paintIcon(this,g,snakeX[0],snakeY[0]);
    }

    for (int i = 1; i < length; i++) {
        Data.body.paintIcon(this,g,snakeX[i],snakeY[i]);
    }

    if (!isStart) {
        g.setColor(Color.black);
        g.setFont(new Font("微软雅黑", Font.BOLD, 20));
        g.drawString("按下空格开始游戏", 170, 35);
    }

    if (isFail) {
        g.setColor(Color.red);
        g.setFont(new Font("微软雅黑", Font.BOLD, 20));
        g.drawString("分数:"+score+"\n按下空格重新开始", 140, 35);
    }

}

@Override
public void keyPressed(KeyEvent e) {
    int keyCode = e.getKeyCode();
    if (keyCode == KeyEvent.VK_SPACE) {
        if (isFail) {
            isFail = false;
            init();
        } else {
            isStart = !isStart;
        }
        repaint();
    }

    if (fx.equals("R")) {
        if (keyCode==KeyEvent.VK_UP) {
            fx = "U";
        } else if (keyCode==KeyEvent.VK_DOWN) {
            fx = "D";
        } else if (keyCode==KeyEvent.VK_RIGHT) {
            fx = "R";
        }
    }

    if (fx.equals("L")) {
        if (keyCode==KeyEvent.VK_UP) {
            fx = "U";
        } else if (keyCode==KeyEvent.VK_DOWN) {
            fx = "D";
        } else if (keyCode==KeyEvent.VK_LEFT) {
            fx = "L";
        }
    }

    if (fx.equals("U")) {
        if (keyCode==KeyEvent.VK_UP) {
            fx = "U";
        } else if (keyCode==KeyEvent.VK_LEFT) {
            fx = "L";
        } else if (keyCode==KeyEvent.VK_RIGHT) {
            fx = "R";
        }
    }

    if (fx.equals("D")) {
        if (keyCode==KeyEvent.VK_DOWN) {
            fx = "D";
        } else if (keyCode==KeyEvent.VK_LEFT) {
            fx = "L";
        } else if (keyCode==KeyEvent.VK_RIGHT) {
            fx = "R";
        }
    }

}

@Override
public void actionPerformed(ActionEvent e) {
    if (isStart && !isFail) {

        //吃食物
        if (snakeX[0] == foodX && snakeY[0] == foodY) {
            length++;
            score++;
            foodX = 0 + 20*random.nextInt(10);
            foodY = 50 + 20*random.nextInt(10);
        }

        //身体+1
        for (int i = length-1; i > 0; i--) {
            snakeX[i] = snakeX[i-1];
            snakeY[i] = snakeY[i-1];
        }

        if (fx.equals("R")) {
            snakeX[0] = snakeX[0]+20;
            if (snakeX[0]>490) {isFail = true;}
        } else if (fx.equals("L")) {
            snakeX[0] = snakeX[0]-20;
            if (snakeX[0]<0) {isFail = true;}
        } else if (fx.equals("U")) {
            snakeY[0] = snakeY[0]-20;
            if (snakeY[0]<50) {isFail = true;}
        } else if (fx.equals("D")) {
            snakeY[0] = snakeY[0]+20;
            if (snakeY[0]>400) {isFail = true;}
        }

        for (int i = 1; i < length; i++) {
            if (snakeX[0] == snakeX[i] && snakeY[0] == snakeY[i]) {
                isFail = true;
            }
        }

        repaint();
    }
    timer.start();
}

@Override
public void keyTyped(KeyEvent e) {

}

@Override
public void keyReleased(KeyEvent e) {

}

}