java - android - 从 Activity View 中调用方法

Question

我正在开发一个 2d 游戏，我试图让我绘制和更新所有内容的 View 告诉包含它的 Activity 游戏结束并在屏幕上显示弹出窗口。问题是我不知道如何从 View 访问 Activity 中的方法，因为它们在不同的线程上工作。

代码看起来或多或少像这样，我想从 View 类访问方法displayFrame()。真实代码中的方法对其他 TextView 等执行更多操作，只有该 Activity 才能访问。

public class MainActivity extends Activity{

    private MyView myView;
    RelativeLayout finalFrame;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        myView = new MyView(this.getApplicationContext());
        this.setContentView(myView);

        finalFrame = (RelativeLayout) findViewById(R.id.framefinal);
    }

    private void displayFrame(){
        this.finalFrame.setVisibility(View.VISIBLE);
    }
}

public class MyView extends SurfaceView implements SurfaceHolder.Callback{
    private MyThread myThread;
    private boolean finished = false;

    public MyView(Context context) {
        super(context);

        getHolder().addCallback(this);
        this.myThread = new MyThread(getHolder(), this);

        this.myThread.setRunning(true);
    }

    public void update() {
        this.finished = someMethod();
        if(this.finished){
            MainActivity.displayFrame();
        }
    }

    public void draw(Canvas canvas){
        //draw something
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {

    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {

    }
}

public class MyThread extends Thread{
    private MyView myView;
    private SurfaceHolder surfaceHolder;
    private boolean running = false;
    private static Canvas canvas;

    public MyThread(SurfaceHolder surfaceHolder, MyView myView){
        super();
        this.surfaceHolder = surfaceHolder;
        this.myView = myView;
    }

    @Override
    public void run(){
        while(running){
            canvas = null;

            try {
                canvas = this.surfaceHolder.lockCanvas();
                synchronized (surfaceHolder) {
                    this.myView.update();
                    this.myView.draw(canvas);
                }
            } catch (Exception e) {e.printStackTrace();}
            finally{
                if(canvas!=null)
                {
                    try {
                        surfaceHolder.unlockCanvasAndPost(canvas);
                    }
                    catch(Exception e){e.printStackTrace();}
                }
            }
        }
    }

    public void setRunning(boolean running){
        this.running = running;
    }
}

Answer 1

最简单的方法是在 View 中定义监听器接口(interface)并让 Activity 实现它。然后您可以通知 Activity 您的游戏已结束并执行适当的逻辑。

public class MyView extends SurfaceView implements SurfaceHolder.Callback {

     // your other fields
     private GameListener mGameListener;

     public void setGameListener(GameListener gameListener) {
         mGameListener = gameListener;
     }

     public void update() {
         // your logic
         if (mGameListener != null) {
             // calling onGameEnd on the main thread
             post(new Runnable() {

                 public void run() {
                     mGameListener.onGameEnd();
                 }

             });
         }
     }

     // rest of your class as it is

     public interface GameListener {

         void onGameEnded();

     }
}

public class MainActivity extends Activity implements GameListener {

    // the rest of your class

    public void onGameEnded() {
        // call the method you need
    } 
}