JAVA小白的第二个项目—飞机大战分步骤理解流程

第二个项目—飞机大战分步骤理解流程"/>

JAVA小白的第二个项目—飞机大战分步骤理解流程

项目简单简介

飞机大战是集成这一个月实训以来的成果，其中包括了所学的封装，继承，多态，方法的重载等多个知识点构成的一款简单的小游戏。经过一个礼拜的时间将此项目完成，由多个模块组成。

这个代码我们一共需要创建7个类

一.如何实现游戏背景图滚动播放

这个游戏首先的第一个问题就是呈现出飞机正在向前飞行的效果，也就是如何将图片一张接着一张无缝的滚动播放
在MySurfacView的画布上将背景图片上传
我们先创建Blackground类，并创建logic方法

package com.example.administrator.myapplication9;import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;public class BackGround {private  int y1;private  int y2;private Bitmap bitmap;public BackGround(Bitmap bitmap){this.bitmap = bitmap;y1=0;y2=y1-bitmap.getHeight();}public void draw(Canvas canvas,Paint paint){logic();canvas.drawBitmap(bitmap,0,y1,paint);canvas.drawBitmap(bitmap,0,y2,paint);}public void logic() {y1+=10;y2+=10;if (y1>=MySurfaceView.height){y1=y2-bitmap.getHeight();//移动到第二张图片的顶部}if (y2>=MySurfaceView.height){y2=y1-bitmap.getHeight();}}
}

如何绘制飞机

我们需要创建一只画笔，锁定画布
并在MySurfaceView中创建run方法

  public void run() {gameSoundPool.playSound(3);Paint paint = new Paint();BackGround backGround = new BackGround(BitmapFactory.decodeResource(getResources(), R.mipmap.img_bg_level_3));plane = new Myplane(BitmapFactory.decodeResource(getResources(), R.mipmap.myplane),BitmapFactory.decodeResource(getResources(), R.mipmap.myhp));BossPlane bossPlane = new BossPlane(BitmapFactory.decodeResource(getResources(), R.mipmap.bossplane));

这样就将敌机和我方机器绘制在了画布上

如何绘制子弹

绘制子弹和绘制飞机的方法类似，创建一个子弹（bullet）类，在MySurfaceView中需要实例化子弹对象，然后将子弹的图片上传，我们还需要创建我方子弹，敌方子弹的数组eg： private VectorbulletVector = new Vector <>();像这样的一个数组用来存放子弹，调用bullet类，在bullet类中创造logic方法，用if语句进行判断，分别进行判断，并给玩家子弹和敌方子弹进行设置

这是先创建一个bullet类，子弹类，并在里面创建方法，设置子弹的运行

这里写package com.example.administrator.myapplication9;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;public class Bullet {private Bitmap bitmap;private int x, y;private int speed = 10;private boolean isDead;private int type;public Bullet(Bitmap bitmap, int x, int y,int type) {this.bitmap = bitmap;this.x = x;this.y = y;this.type = type;}public Bullet() {}public void draw(Canvas canvas, Paint paint) {canvas.drawBitmap(bitmap, x, y, paint);logic();}public void logic() {switch (type){//玩家子弹case 0:y -= speed+5;if (y < 0) {isDead = true;}break;//Boss子弹case 1:y += speed+8;if (y < 0) {isDead = true;}break;default:break;}}public boolean isDead() {return isDead;}public Bitmap getBitmap(){return bitmap;}public int getX(){return x;}public int getY() {return y;}public void setDead(boolean dead) {isDead = dead;}
}代码片

这是在MySurfacView中如何调用bullet类，并且进行实例化，用循环语句实现运行

这一段代码是在开始创建子弹的数组

 private Vector<Bullet>bulletVector = new Vector <>();private Vector<Bullet>bossBulletVector = new Vector <>();private Vector<Bullet>boomVector = new Vector <>();

 public void run() {gameSoundPool.playSound(3);Paint paint = new Paint();BackGround backGround = new BackGround(BitmapFactory.decodeResource(getResources(), R.mipmap.img_bg_level_3));plane = new Myplane(BitmapFactory.decodeResource(getResources(), R.mipmap.myplane),BitmapFactory.decodeResource(getResources(), R.mipmap.myhp));BossPlane bossPlane = new BossPlane(BitmapFactory.decodeResource(getResources(), R.mipmap.bossplane));while (isDrawing) {count++;try {canvas = surfaceHolder.lockCanvas();//锁定（选定）画布canvas.drawColor(Color.WHITE);switch (GAME_STATE){case 0:backGround.draw(canvas, paint);plane.draw(canvas, paint);bossPlane.draw(canvas,paint);if(count%20==0){gameSoundPool.playSound(1);Bullet bullet = new Bullet(BitmapFactory.decodeResource(getResources(), R.mipmap.mybullet),plane.getX(),plane.getY(),0);Bullet bullet1 = new Bullet(BitmapFactory.decodeResource(getResources(), R.mipmap.mybullet),plane.getX()+plane.getWidth(),plane.getY(),0);bulletVector.add(bullet);bulletVector.add(bullet1);}for (int i = 0;i<bulletVector.size();i++) {if (bulletVector.elementAt(i).isDead()) {bulletVector.remove(i);}}for (int i = 0;i<bulletVector.size();i++){bulletVector.elementAt(i).draw(canvas,paint);if (bossPlane.isCollision(bulletVector.elementAt(i))){gameSoundPool.playSound(2);Boom boom = new Boom(BitmapFactory.decodeResource(getResources(),R.mipmap.boom),bossPlane.getX()+bossPlane.getFrameW()/4,bossPlane.getY(),7);boomVector.add(boom);}}for (int i=0;i<boomVector.size();i++){if (boomVector.elementAt(i).isDead()){boomVector.remove(i);}else{boomVector.elementAt(i).draw(canvas,paint);}}if(count%40==0){Bullet bullet = new Bullet(BitmapFactory.decodeResource(getResources(), R.mipmap.bossbullet),bossPlane.getX()+bossPlane.getFrameW ()/2,bossPlane.getY()+bossPlane.getFrameH(),1);         //Bullet bullet1 = new Bullet(BitmapFactory.decodeResource(getResources(), R.mipmap.bossbullet),bossPlane.getX()+bossPlane.getFrameW(),bossPlane.getY()+bossPlane.getFrameH(),1);bossBulletVector.add(bullet);// bossBulletVector.add(bullet1);}for (int i = 0;i < bossBulletVector.size(); i++) {if (bossBulletVector.elementAt(i).isDead()) {bossBulletVector.remove(i);}}for (int i = 0;i < bossBulletVector.size(); i++){bossBulletVector.elementAt(i).draw(canvas,paint);plane.isCollision(bossBulletVector.elementAt(i));}plane.isCollision(bossPlane);break;case 1:RectF rectF1 = new RectF(0,0,getWidth(),getHeight());canvas.drawBitmap(BitmapFactory.decodeResource(getResources(),R.mipmap.gamewin),null,rectF1,paint);break;case 2:RectF rectF = new RectF(0,0,getWidth(),getHeight());canvas.drawBitmap(BitmapFactory.decodeResource(getResources(),R.mipmap.gamelost),null,rectF,paint);break;}} catch (Exception e) {e.printStackTrace();} finally {if (canvas != null) {surfaceHolder.unlockCanvasAndPost(canvas);//解锁画布，显示到屏幕上}}

以上这一段是完整的一段run方法，里面有子弹的绘制，还有如何运行程序，下面这一小段代码就是如何在MySurfaceView里如何绘制子弹

 Bullet bullet = new Bullet(BitmapFactory.decodeResource(getResources(), R.mipmap.bossbullet),bossPlane.getX()+bossPlane.getFrameW()/2,bossPlane.getY()+bossPlane.getFrameH(),1);//Bullet bullet1 = new Bullet(BitmapFactory.decodeResource(getResources(), R.mipmap.bossbullet),bossPlane.getX()+bossPlane.getFrameW(),bossPlane.getY()+bossPlane.getFrameH(),1);bossBulletVector.add(bullet);// bossBulletVector.add(bullet1);

实例化，然后将子弹绘制出来

如何判断碰撞

在飞机大战中碰撞分为两种，飞机与飞机的碰撞，能够子弹与飞机的碰撞，而这一段也是非常重要的，我们需要知道飞机的位置，get到飞机的位置，当我方飞机碰撞到敌方飞机的顶部，或子弹打到时，敌方飞机有爆炸效果（爆炸效果如何实现，下文会写），左右时，我方飞机进行闪烁，同样，当敌方子弹闯入我方飞机的范围内，我方飞机闪烁，并且减少血量
在Myplane中建立两个方法 noCollision（Boss），isCollision（myplane）
并用if语句进行条件判断如果碰到血量就–

public void draw(Canvas canvas,Paint paint){if (hp<=0){MySurfaceView.GAME_STATE= 2;}if (noCollision){noCollisionCount++;if (noCollisionCount%10==0){canvas.drawBitmap(bitmap,x,y,paint);//飞机闪烁}if (noCollisionCount>100){//无敌时间noCollision = false;noCollisionCount = 0;}}else {//非无敌状态canvas.drawBitmap(bitmap,x,y,paint);}for (int i = 0; i<hp; i++){canvas.drawBitmap(bitmapHp,i*bitmapHp.getWidth(),MySurfaceView.height-bitmapHp.getHeight(),paint);}}public void touchEvent(MotionEvent event){if (event.getAction()==MotionEvent.ACTION_MOVE){float ex = (int) event.getX();float ey = (int) event.getY();if (ex>x&&ex<x+width&&ey>y&&ey<y+height){x = (int) ex-width/2;y = (int) ey-height/2;if(y<0){y=0;}if(y+height>MySurfaceView.height){y=MySurfaceView.height-height;}}}```` public boolean isCollision(Bullet bullet){if (noCollision){return false;}else{if (bullet.getX()>x&&bullet.getX()<x+width&&bullet.getY()>y&&bullet.getY()<y+height){noCollision = true;if (hp>0){hp--;}return true;}}return false;}上面的这两段代码实现的判断碰撞，然后不同的飞机的不同反应<div class="se-preview-section-delimiter"></div>####如何绘制爆炸效果
当飞机子弹打到敌方飞机时会有爆炸效果，我们需要新建一个Bomm类<div class="se-preview-section-delimiter"></div>

package com.example.administrator.myapplication9;

import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;

public class Boom extends Bullet {
private Bitmap bitmap;
private int x,y;
private int totalFrame;
private int currentFrame;
private int frameW,frameH;
private boolean isEnd;

public Boom(Bitmap bitmap, int x, int y, int totalFrame) {super();this.bitmap = bitmap;this.x = x;this.y = y;this.totalFrame = totalFrame;frameW = bitmap.getWidth()/totalFrame;frameH =  bitmap.getHeight();
}
public void  draw(Canvas canvas, Paint paint){canvas.save();canvas.clipRect(x,y,x+frameW,y+frameH);canvas.drawBitmap(bitmap,x-currentFrame*frameW,y,paint);canvas.restore();logic();}
public void logic(){if (currentFrame<totalFrame){currentFrame++;}else{isEnd = true;}
}public boolean isEnd() {return isEnd;
}

}

同样我们需要get到位置，爆炸的效果是一帧一帧显示的，并且在MySurfaceView中调用，运用for循环<div class="se-preview-section-delimiter"></div>

for (int i = 0;i

package com.example.administrator.myapplication9;import android.content.Context;
import android.media.AudioManager;
import android.media.SoundPool;public class GameSoundPool {private SoundPool soundPool;private int s1;private int s2;private int s3;
-public GameSoundPool(Context context){this.soundPool = new SoundPool(2, AudioManager.STREAM_MUSIC,0);s1 = soundPool.load(context,R.raw.shoot,1);s2 = soundPool.load(context,R.raw.explosion2,1);// s3 = soundPool.load(context,R.raw.bg_logobg,2);}public void playSound(int s) {switch (s){case 1:soundPool.play(s1,1,1,1,1,1.0f);break;case 2:soundPool.play(s2,1,1,1,1,1.0f);break;case 3:soundPool.play(s3,1,1,1,1,1.0f);break;}}}

用switch,case语句进行判断，然后将在MySurfaceView中，将这些音乐写入合适的位置，比如在boss发射子弹时运行哪一个音乐，音乐代码中的参数分别是左右声道，音乐的播放速率。