snakecanvas.java

j2me下贪吃蛇源代码

package snake;

import java.util.*;
import javax.microedition.lcdui.*;

/**
 * 贪吃蛇游戏
 */
public class SnakeCanvas extends Canvas  implements Runnable{
    /**存储贪吃蛇节点坐标,其中第二维下标为0的代表x坐标，第二维下标是1的代表y坐标*/
    int[][] snake = new int[200][2];
    /**已经使用的节点数量*/
    int snakeNum;
    /**贪吃蛇运动方向,0代表向上，1代表向下,2代表向左,3代表向右*/
    int direction;
    /*移动方向*/
    /**向上*/
    private final int DIRECTION_UP = 0;
    /**向下*/
    private final int DIRECTION_DOWN = 1;
    /**向左*/
    private final int DIRECTION_LEFT = 2;
    /**向右*/
    private final int DIRECTION_RIGHT = 3;

    /**游戏区域宽度*/
    int width;
    /**游戏区域高度*/
    int height;

    /**蛇身单元宽度*/
    private final byte SNAKEWIDTH = 4;

    /**是否处于暂停状态,true代表暂停*/
    boolean isPaused = false;
    /**是否处于运行状态,true代表运行*/
    boolean isRun = true;

    /**时间间隔*/
    private final int SLEEP_TIME = 300;

    /**食物的X坐标*/
    int foodX;
    /**食物的Y坐标*/
    int foodY;
    /**食物的闪烁控制*/
    boolean b = true;

    /**Random对象*/
    Random random = new Random();

    public SnakeCanvas() {
     //初始化
        init();
        width = this.getWidth();
        height = this.getHeight();
        //启动线程
        new Thread(this).start();
    }

    /**
     * 初始化开始数据
     */
    private void init(){
        //初始化节点数量
        snakeNum = 7;
        //初始化节点数据
        for(int i = 0;i < snakeNum;i++){
                snake[i][0] = 100 - SNAKEWIDTH * i;
                snake[i][1] = 40;
        }
        //初始化移动方向
        direction = DIRECTION_RIGHT;
        //初始化食物坐标
        foodX = 100;
        foodY = 100;
    }

    protected void paint(Graphics g) {
        //清屏
        g.setColor(0xffffff);
        g.fillRect(0,0,width,height);
        g.setColor(0);

        //绘制蛇身
        for(int i = 0;i < snakeNum;i++){
            g.fillRect(snake[i][0],snake[i][1],SNAKEWIDTH,SNAKEWIDTH);
        }
        //绘制食物
        if(b){
         g.fillRect(foodX,foodY,SNAKEWIDTH,SNAKEWIDTH);
        }
    }

    private void move(int direction){
        //蛇身移动
        for(int i = snakeNum - 1;i > 0;i--){
            snake[i][0] = snake[i - 1][0];
            snake[i][1] = snake[i - 1][1];
        }

        //第一个单元格移动
        switch(direction){
        case DIRECTION_UP:
            snake[0][1] = snake[0][1] - SNAKEWIDTH;
            break;
        case DIRECTION_DOWN:
            snake[0][1] = snake[0][1] + SNAKEWIDTH;
            break;
        case DIRECTION_LEFT:
            snake[0][0] = snake[0][0] - SNAKEWIDTH;
            break;
        case DIRECTION_RIGHT:
            snake[0][0] = snake[0][0] + SNAKEWIDTH;
            break;
        }
    }
    /**
     * 吃掉食物，自身增长
     */
    private void eatFood(){
     //判别蛇头是否和食物重叠
     if(snake[0][0] == foodX && snake[0][1] == foodY){
      snakeNum++;
      generateFood();
     }
    }
    /**
     * 产生食物
     * 说明：食物的坐标必须位于屏幕内，且不能和蛇身重合
     */
    private void generateFood(){
     while(true){
      foodX = Math.abs(random.nextInt() % (width - SNAKEWIDTH + 1))
                        / SNAKEWIDTH * SNAKEWIDTH;
      foodY = Math.abs(random.nextInt() % (height - SNAKEWIDTH + 1))
                        / SNAKEWIDTH * SNAKEWIDTH;
      boolean b = true;
      for(int i = 0;i < snakeNum;i++){
       if(foodX == snake[i][0] && snake[i][1] == foodY){
        b = false;
        break;
       }
      }
      if(b){
       break;
      }
     }
    }

    /**
     * 判断游戏是否结束
     * 结束条件：
     *        1、蛇头超出边界
     *        2、蛇头碰到自身
     */
    private boolean isGameOver(){
     //边界判别
     if(snake[0][0] < 0 || snake[0][0] > (width - SNAKEWIDTH) ||
        snake[0][1] < 0 || snake[0][1] > (height - SNAKEWIDTH)){
      return true;
     }
     //碰到自身
     for(int i = 4;i < snakeNum;i++){
      if(snake[0][0] == snake[i][0]
         && snake[0][1] == snake[i][1]){
       return true;
      }
     }

     return false;
    }

 /**
  * 事件处理
  */
    public void keyPressed(int keyCode){
        int action = this.getGameAction(keyCode);
        //改变方向
        switch(action){
        case UP:
            if(direction != DIRECTION_DOWN){
                direction = DIRECTION_UP;
            }
            break;
        case DOWN:
            if(direction != DIRECTION_UP){
                direction = DIRECTION_DOWN;
            }
            break;
        case LEFT:
            if(direction != DIRECTION_RIGHT){
                direction = DIRECTION_LEFT;
            }
            break;
        case RIGHT:
            if(direction != DIRECTION_LEFT){
                direction = DIRECTION_RIGHT;
            }
            break;
        case FIRE:
         //暂停和继续
            isPaused = !isPaused;
            break;
        }
    }

 /**
  * 线程方法
  * 使用精确延时
  */
    public void run(){
        try{
            while (isRun) {
             //开始时间
             long start = System.currentTimeMillis();


                if(!isPaused){
                    //吃食物
                    eatFood();
                    //移动
                    move(direction);

                    //结束游戏
                    if(isGameOver()){
                     break;
                    }

                    //控制闪烁
                    b = !b;
                }
                //重新绘制
                repaint();

                long end = System.currentTimeMillis();

                //延时
                if(end - start < SLEEP_TIME){
                 Thread.sleep(SLEEP_TIME - (end - start));
                }
            }
        }catch(Exception e){}
    }
}