本人做了些修改
修正如下：
1、修正了按键与行进方向相反而死的bug
2、修正了连续按键可以加速的bug </div>

 

GreedySnake.java         

package com.fred.test;  import java.awt.event.KeyListener;  import java.awt.event.KeyEvent;  import java.awt.Graphics;  import java.awt.Point;  import java.awt.Color;  import java.util.Random;  import java.util.List;  import java.util.LinkedList;  import javax.swing.JPanel;  import javax.swing.JFrame;    class Food{   Snake snake;   int x,y;   boolean flag;   Food(Snake snake){    this.snake = snake;    flag = true;    int x = 0;    int y = 0;    while(flag){     flag = false;     x = Math.abs(new Random().nextInt()%40);     y = Math.abs(new Random().nextInt()%40);     if(snake.head.x==x && snake.head.y==y) flag = true;     for(Point it:snake.body) if(it.x==x && it.y==y) flag = true;    }    this.x = x;    this.y = y;   }     }  class Snake{   int size,length,dir;   List<Point> body;   Point head;   Snake(Point head){    size = 10;    length = 5;dir = 4;    this.head = head;    body = new LinkedList<Point>();    for(int i=0;i<length-1;i++){     Point p = new Point(head.x,head.y+1+i);     body.add(p);    }   }   boolean isEat(Food food){    if(head.x==food.x && head.y==food.y) return true;    return false;   }   boolean isOut(){    if(head.x<0 || head.y<0 || head.x>=40 || head.y>=40)     return true;    return false;   }   boolean isPitch(){    for(Point it:body)     if(head.x==it.x && head.y==it.y){      dead(1);      return true;     }    return false;   }   void dead(int way){    System.exit(way);   }  }  class MyPanel extends JPanel implements KeyListener,Runnable{   Snake snake;   Food food;   int speed;   MyPanel(Snake snake,Food food){    this.snake = snake;    this.food = food;    speed = 526;   }   public void paint(Graphics g){    super.paint(g);    g.fillRect(0,0,400,400);    g.setColor(Color.YELLOW);    g.fillRect(snake.head.x*snake.size,snake.head.y*snake.size,snake.size,snake.size);    g.setColor(Color.ORANGE);    for(Point it:snake.body) g.fillRect(it.x*snake.size,it.y*snake.size,snake.size,snake.size);    g.setColor(Color.GREEN);    g.fillRect(food.x*snake.size,food.y*snake.size,snake.size,snake.size);   }   //自动行进   public void keyPressed(Integer dir){        Point oxy = new Point(snake.head);     if(dir==3){      snake.head.x--;     }     else if(dir==4){      snake.head.x++;     }     else if(dir==1){      snake.head.y--;     }     else if(dir==2){      snake.head.y++;     }else return;        if(snake.isOut()) snake.dead(1);      snake.body.add(0,oxy);    if(snake.isEat(food)){     snake.length++;     if(speed >= 50) speed-=25;     food = new Food(snake);    }else snake.body.remove(snake.length-1);        if(snake.isPitch()) snake.dead(2);    repaint();   }   //按键仅用于修改蛇的方向   public void keyPressed(KeyEvent e){    int key = e.getKeyCode();    //按鍵和行進方向相反，按鍵無效直接返回！    if(((key==KeyEvent.VK_LEFT && snake.dir==4)||(key==KeyEvent.VK_UP && snake.dir==2)      ||(key==KeyEvent.VK_DOWN && snake.dir==1)||(key==KeyEvent.VK_RIGHT && snake.dir==3))){     return;    }     if(key == KeyEvent.VK_LEFT){      snake.dir = 3;     }     else if(key == KeyEvent.VK_RIGHT){      snake.dir = 4;     }     else if(key == KeyEvent.VK_UP){      snake.dir = 1;     }     else if(key == KeyEvent.VK_DOWN){      snake.dir = 2;     }else return;           }   public void keyReleased(KeyEvent e){}   public void keyTyped(KeyEvent e){}      public synchronized void run(){     while(true){     try{Thread.sleep(speed);     }catch(Exception e){}     keyPressed(snake.dir);    }   }  }  public class GreedySnake extends JFrame{   MyPanel mp;   Snake snake;   Food food;   Thread t;   public GreedySnake(){    snake = new Snake(new Point(5,5));    food = new Food(snake);    mp = new MyPanel(snake,food);    t = new Thread(mp);    t.start();    add(mp);    addKeyListener(mp);    setTitle("GreedySnake");    setSize(40*10 + 15,40*10 + 38);    setLocation(200,200);    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);    setVisible(true);   }   public static void main(String[] args){    new GreedySnake();   }  }