snake.java

一个简单的贪吃蛇游戏

package cn.edu.usc.snake.entities;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Point;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;

import cn.edu.usc.snake.listener.SnakeListener;
import cn.edu.usc.snake.util.ConstValue;
import cn.edu.usc.snake.util.Direction;

public class Snake {
	
	private LinkedList<Point> body;
	private Direction oldDirection, newDirection;
	
	private Set<SnakeListener> listeners = new HashSet<SnakeListener>();
	
	private Point oldTail;
	private boolean alive;
	private int eatFoodCount;
	
	public Snake() {
		initSnake();
	}
	
	/**
	 * 初始化蛇
	 */
	public void initSnake() {
		int x = 1;
		int y = 0;
		alive = true;
		eatFoodCount = 0;
		body = new LinkedList<Point>();
		for(int i = 0; i < 3; i ++) {
			body.addFirst(new Point(x, y ++));
		}
		this.oldDirection = this.newDirection = Direction.D;
	}

	/**
	 * 移动（走一步）
	 * 增加蛇头，去掉蛇尾
	 */
	public void move() {
		if(!this.checkInvalidDirection(this.oldDirection, this.newDirection)) {
			this.oldDirection = this.newDirection;
		}
		//去掉蛇尾
		oldTail = body.removeLast();
		
		int x = body.getFirst().x;
		int y = body.getFirst().y;
		
		switch(oldDirection) {
		case L:
			x --;
			if(x < 0) {
				x = ConstValue.PANEL_WIDTH;
			}
			break;
		case U:
			y --;
			if(y < 0) {
				y = ConstValue.PANEL_HEIGHT;
			}
			break;
		case R:
			x ++;
			if(x >= ConstValue.PANEL_WIDTH) {
				x = 0;
			}
			break;
		case D:
			y ++;
			if(y >= ConstValue.PANEL_HEIGHT) {
				y = 0;
			}
			break;
		}
		Point snakeHead = new Point(x,y);
		//增加蛇头
		body.addFirst(snakeHead);
	}
	
	/**
	 * 判断2个方向是否相反
	 * @param oldDire
	 * @param newDire
	 * @return
	 */
	private boolean checkInvalidDirection(Direction oldDire,Direction newDire) {
		boolean result = false;
		
		switch (oldDire) {
			case L:
				if (newDire == Direction.R) {
					result = true;
				}
				break;
			case U:
				if (newDire == Direction.D) {
					result = true;
				}
				break;
			case R:
				if (newDire == Direction.L) {
					result = true;
				}
				break;
			case D:
				if (newDire == Direction.U) {
					result = true;
				}
				break;
		}
		return result;
	}
	
	/**
	 * 改变方向
	 */
	public void changeDirection(Direction dire) {
		if(!this.checkInvalidDirection(this.newDirection, dire)) {
			this.newDirection = dire;
		}
	}
	
	/**
	 * 吃食物（身体变长）
	 */
	public void eatFood() {
		body.addLast(oldTail);
		this.eatFoodCount ++;
	}
	
	/**
	 * 蛇是否迟到了自己的身体
	 */
	public boolean isEatBody() {
		for(int i = 1; i < body.size(); i ++) {
			if(body.get(i).equals(this.getHead())) {
				return true;
			}
		}
		return false;
	}
	
	/**
	 * 显示
	 * @param g 
	 */
	public void drawMe(Graphics g) {
		Color c = g.getColor();
		
		for(Point p : body) {
			if(p.equals(getHead())) {
				g.setColor(Color.GREEN);
			} else {
				g.setColor(Color.LIGHT_GRAY);
			}
			g.fillRoundRect(p.x * ConstValue.CELL_WIDTH, 
					p.y * ConstValue.CELL_HEIGHT, 
					ConstValue.CELL_WIDTH,
					ConstValue.CELL_HEIGHT,
					ConstValue.CELL_RECT_SIZE,
					ConstValue.CELL_RECT_SIZE);
		}
		g.setColor(c);
	}
	
	/**
	 * 返回蛇头坐标
	 * @return
	 */
	public Point getHead() {
		return body.getFirst();
	}
	
	/**
	 * 检查点p是否为蛇体的一部分
	 * @param p
	 * @return
	 */
	public boolean isInSnake(Point p) {
		for(Point s : body) {
			if(s.equals(p)) {
				return true;
			}
		}
		return false;
	}
	
	/**
	 * 蛇移动线程启动
	 */
	public void start() {
		new Thread(new SnakeDriver()).start();
	}
	
	/**
	 * 注册监听器
	 * @param l
	 */
	public void addSnakeListener(SnakeListener l) {
		if(null != l) {
			this.listeners.add(l);
		}
	}
	
	/**
	 * 蛇移动线程
	 * @author HP
	 *
	 */
	private class SnakeDriver implements Runnable {
		@Override
		public void run() {
			while(alive) {
				move();
				for(SnakeListener l : listeners) {
					l.snakeMove(Snake.this);
				}
				try {
					Thread.sleep(ConstValue.SNAKE_SPEED);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		}
		
	}

	public void die() {
		this.alive = false;
	}

	public boolean isAlive() {
		return alive;
	}

	public int getEatFoodCount() {
		return eatFoodCount;
	}
}