如何使用SurfaceView实现鱼儿游动动画

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  android:orientation="vertical"  android:layout_width="match_parent"  android:layout_height="match_parent">  <com.example.liuyan.testbutfly.FishView   android:layout_width="match_parent"   android:layout_height="match_parent" /> </LinearLayout> 

public class FishView extends SurfaceView implements SurfaceHolder.Callback{  private SurfaceHolder holder;  private UpdateViewThread updatethread;  private boolean hasSurface;  private Bitmap back;  private Bitmap[] fishs;  private int fishIndex = 0;//绘制第几张鱼  //鱼的初始位置  private float fishx = 778;  private float fishy = 500;  private float fishSpeed = 6; //鱼的游动速度  //鱼的游动角度  private int fishAngle = new Random().nextInt(60);  Matrix matrix = new Matrix();   public FishView(Context context) {   super(context);   Log.i("mydate" , "开始");   //获取surfaceview的surfaceholder，并将该类的实例作为其callback   holder = getHolder();   holder.addCallback(this);//以自身作为callback,回调方法   hasSurface = false;   back = BitmapFactory.decodeResource(context.getResources() , R.drawable.fishbg);//背景   int[] id = new int[]{R.drawable.fish0 , R.drawable.fish1 , R.drawable.fish2 ,R.drawable.fish3 ,R.drawable.fish4 ,R.drawable.fish5 ,R.drawable.fish6 ,R.drawable.fish7 ,R.drawable.fish8, R.drawable.fish9};   fishs = new Bitmap[10];   //初始化 鱼游动的10张图   for (int i = 0 ; i < 10 ; i++){    try {     fishs[i] = BitmapFactory.decodeResource(context.getResources() , id[i]);    } catch (Exception e){     e.printStackTrace();    }   }   Log.i("mydate" , "结束");  }   public FishView(Context context, AttributeSet attrs) {   super(context, attrs);   Log.i("mydate" , "开始");   //获取surfaceview的surfaceholder，并将该类的实例作为其callback   holder = getHolder();   holder.addCallback(this);//以自身作为callback,回调方法   hasSurface = false;   back = BitmapFactory.decodeResource(context.getResources() , R.drawable.fishbg);//背景   int[] id = new int[]{R.drawable.fish0 , R.drawable.fish1 , R.drawable.fish2 ,R.drawable.fish3 ,R.drawable.fish4 ,R.drawable.fish5 ,R.drawable.fish6 ,R.drawable.fish7 ,R.drawable.fish8, R.drawable.fish9};   fishs = new Bitmap[10];   //初始化 鱼游动的10张图   for (int i = 0 ; i < 10 ; i++){    try { //    int fishId = (Integer) R.drawable.class.getField("fish" + i).get(null);//反射机制获取图片 //    Log.i("mydate" , " "+ fishId);     fishs[i] = BitmapFactory.decodeResource(context.getResources() , id[i]);    } catch (Exception e){     e.printStackTrace();    }   }   Log.i("mydate" , "结束");  }    public void resume(){   //创建和启动 图片更新线程   if (updatethread == null){    updatethread = new UpdateViewThread();    if (hasSurface == true){     updatethread.start();    }   }  }   public void pause(){   //停止 图像更新线程   if (updatethread != null){    updatethread.requestExitAndWait();    updatethread = null;   }  }    @Override  public void surfaceCreated(SurfaceHolder holder) { //surfaceview被创建时回调该方法   hasSurface = true;   resume(); //开启线程更新  }   @Override  public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {//surfaceview改变时回调该方法   if (updatethread != null){    updatethread.onWindowResize(width , height);   }  }   @Override  public void surfaceDestroyed(SurfaceHolder holder) {//surfaceview销毁时回调该方法   hasSurface = false;   pause(); //停止线程更新  }   class UpdateViewThread extends Thread{   //定义图像是否更新完成的标志   private boolean done;    public UpdateViewThread() {    super();    done = false;   }    @Override   public void run() {    SurfaceHolder surfaceholder = holder;    //循环绘制，直到线程停止    while (!done){     Canvas canvas = surfaceholder.lockCanvas();//锁定surfaceview,准备绘制     //绘制背景     canvas.drawBitmap(back , 0 , 0 , null);     //鱼游出屏幕外，重新初始化鱼的位置     if (fishx < 0 ){      fishx = 778;      fishy = 500;      fishAngle = new Random().nextInt(60);     }     if (fishy < 0){      fishx = 778;      fishy = 500;      fishAngle = new Random().nextInt(60);     }     //用matrix控制鱼的旋转角度和位置     matrix.reset();     matrix.setRotate(fishAngle);//下面的位置计算看图片的解释如下：     matrix.postTranslate(fishx -= fishSpeed * Math.cos(Math.toRadians(fishAngle)) , fishy -= fishSpeed * Math.sin(Math.toRadians(fishAngle)));     canvas.drawBitmap(fishs[fishIndex++%fishs.length] , matrix , null);     surfaceholder.unlockCanvasAndPost(canvas);//解锁canvas，渲染绘制图像     try {      Thread.sleep(60);     } catch (Exception e){      e.printStackTrace();     }    }   }    public void requestExitAndWait() {    //将绘制线程 标记为完成 ,并合并到主线程中    done = true;    try {     join();    } catch (Exception e){     e.printStackTrace();    }   }    public void onWindowResize(int width, int height) {    //处理surfaceview的大小改变事件   }  }  } 

Math.toRadians(fishAngle)