public class GameStart{
 public static void main(String[] args) {
  JFrame jFrame = new JFrame();
  jFrame.setBounds(100,100,900,720);
  jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
  jFrame.setResizable(false);
  jFrame.add(new GameJPanel());
  jFrame.setVisible(true);
 }
}

//面板
public class GameJPanel extends JPanel implements ActionListener {

 int length;//蛇的長度
 int[] snakeX = new int[600];//蛇的X的最大長度
 int[] snakeY = new int[500];//蛇的Y的最大長度
 String fx = "R";
 boolean isStart = false;//默認不開始
 //定時器
 Timer timer = new Timer(100, this);//100毫秒=1秒
 int foodX;
 int foodY;
 Random random = new Random();//隨機數
 boolean isFail = false;//失敗條件
 int score;

 public GameJPanel() {
  init();
  this.setFocusable(true);//獲取焦點事件
  addKeyListener(new GameKeyListener(this));
  //開啟定時器
  timer.start();
 }
 //初始化
 void init() {
  length = 3;
  snakeX[0] = 100;
  snakeY[0] = 100;//第一個身體
  snakeX[1] = 75;
  snakeY[1] = 100;//第二個身體
  snakeX[2] = 50;
  snakeY[2] = 100;//第三個身體
  fx = "R";
  //食物隨機分布
  foodX = 25 + 25 * random.nextInt(34);
  foodY = 75 + 25 * random.nextInt(24);
  score = 0;
 }
 //繪制面板,所有東西都是通過graphics這個畫筆繪制
 @Override
 protected void paintComponent(Graphics graphics) {
  super.paintComponent(graphics);//清屏
  //添加靜態(tài)布局
  GameData.header.paintIcon(this, graphics, 25, 11);
  graphics.fillRect(25, 75, 850, 600);
  //積分板
  graphics.setColor(Color.white);
  graphics.setFont(new Font("微軟雅黑", Font.BOLD, 18));
  graphics.drawString("長度："+length,750,35);
  graphics.drawString("得分："+score,750,55);
  //先畫食物，防止吃掉有延遲
  GameData.food.paintIcon(this, graphics, foodX, foodY);
  //畫小蛇
  switch (fx) {
   case "R":
    GameData.right.paintIcon(this, graphics, snakeX[0], snakeY[0]);
    break;
   case "L":
    GameData.left.paintIcon(this, graphics, snakeX[0], snakeY[0]);
    break;
   case "U":
    GameData.up.paintIcon(this, graphics, snakeX[0], snakeY[0]);
    break;
   case "D":
    GameData.down.paintIcon(this, graphics, snakeX[0], snakeY[0]);
    break;
  }
  //身體
  for (int i = 1; i < length; i++) {
   GameData.body.paintIcon(this, graphics, snakeX[i], snakeY[i]);
  }
  //游戲狀態(tài)
  if (!isStart) {
   graphics.setColor(Color.white);
   graphics.setFont(new Font("微軟雅黑", Font.BOLD, 40));//設置字體
   graphics.drawString("按下空格，開始游戲", 300, 300);
  }
  //游戲失敗
  if (isFail) {
   graphics.setColor(Color.red);
   graphics.setFont(new Font("微軟雅黑", Font.BOLD, 40));
   graphics.drawString("游戲失敗,請按空格繼續(xù)", 300, 300);
  }
 }
 //事件監(jiān)聽--固定事件刷新一次，1s=100ms
 @Override
 public void actionPerformed(ActionEvent actionEvent) {
  if (isStart && !isFail) {
   //吃食物
   if (snakeX[0] == foodX && snakeY[0] == foodY) {
    //長度+1
    length++;
    score+=10;
    //重新隨機繪制食物
    foodX = 25 + 25 * random.nextInt(34);
    foodY = 75 + 25 * random.nextInt(24);
   }
   //后一節(jié)移動到前一節(jié)，從而由頭帶動身體移動
   for (int i = length - 1; i > 0; i--) {
    snakeX[i] = snakeX[i - 1];
    snakeY[i] = snakeY[i - 1];
   }
   switch (fx) {
    case "R":
     snakeX[0] += 25;//頭部移動
     // 邊界判斷
     if (snakeX[0] > 850) { snakeX[0] = 25; }
     break;
    case "L":
     snakeX[0] -= 25;//頭部移動
     if (snakeX[0] < 25) { snakeX[0] = 850; }
     break;
    case "U":
     snakeY[0] -= 25;//頭部移動
     if (snakeY[0] < 75) { snakeY[0] = 650; }
     break;
    case "D":
     snakeY[0] += 25;//頭部移動
     if (snakeY[0] > 650) { snakeY[0] = 75; }
     break;
   }
   //失敗判定
   for (int i = 1; i < length; i++) {
    if (snakeX[0] == snakeX[i] && snakeY[0] == snakeY[i]) {
     isFail = true;
     break;
    }
   }
   repaint();//重繪
  }
  //開啟定時器
  timer.start();
 }
}