ufo.java

一款基于j2me技术的手机版游戏——飞机射击

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

class UFO
    extends Sprite {
  private Image ufoImg=null, burstImg=null;
  private MyShip myship;
  private int missileCount=0;
  private int direction;
  static final int DIRECTION_RIGHT = 0 ;
  static final int DIRECTION_LEFT = 1 ;
  int id;//飞机类型图片
  private Random random = new Random();
  public UFO(MyShip myship) {
    this.myship = myship;
    if (ufoImg == null) {
      try {
        id = (random.nextInt() >>> 1)%2;
//        System.out.println("id     =   "+id);
        switch(id){//装载敌人飞机图片
          case 0:
            ufoImg = Image.createImage("/ufoImg.png");
            break;
          case 1:
            ufoImg = Image.createImage("/n13.png");
            break;
        }
        burstImg = Image.createImage("/burstImg.png");
      }
      catch (Exception e) {}
    }
    width = ufoImg.getWidth();
    height = ufoImg.getHeight();
  }

  void setAlive(boolean isAlive){//飞机是否在界面类和是否还活着
    if(isAlive){
      this.isHit = false ;
      missileCount = 0 ;
      tickCount = 0 ;
    }
    super.setAlive(isAlive);
  }

  void doMove() {//飞机移动
    if(isAlive){
      if (isHit()) {
        tickCount++;
        if (tickCount > 4) {
          setAlive(false);
        }
      }
      else {
        switch(direction){
          case DIRECTION_RIGHT :
            x= x + (width/2) + 1 ;
            break;
          case DIRECTION_LEFT :
            x= x - (width/2) - 1 ;
            break;

        }
      }
    }
  }

  void doDraw(Graphics g) {//画飞机或者爆炸
    if (isAlive){
      if (isHit()) {
        g.drawImage(burstImg, x, y, 20);
      }
      else {
        g.drawImage(ufoImg, x, y, 20);
      }
    }
  }

  void setDirection(int direction){//飞机出来方向
    this.direction = direction ;
  }
  boolean isDropBome(){//爆炸
    if (missileCount <3){
      int center = x+(width/2);
      if (center >= myship.getX()&&center <= myship.getX()+myship.getwidth()){
        missileCount++;
        return true ;
      }
    }
    return false;
  }
}