Android：AsyncTask，onPostExecute在doInBackground完成之前启动

问题描述：

几个小时前我有这个问题（Android: AsyncTask, my 1st task has not finished when the other starts）我把它解决了，但后来我意识到我有类似的问题。Android：AsyncTask，onPostExecute在doInBackground完成之前启动

这是我的主类 “GameActivity”

   public void mainmethod() 
        Log.w("GAMEACTIVITY","actionup"); 
        myAsyncRunnable mar = new myAsyncRunnable(GameActivity.this); 
        mar.execute("fire"); 

public void doPhotoTask() { 
    PhotoTask photoTask = new PhotoTask(camera,surfaceCamera,isPreview,holder,GameActivity.this); 
    photoTask.execute(null); 
}

在myAsyncRunnable.fire

（）我有一个环而改变gameActivity一个ImageView的> 10倍的图像。我希望在最后的图像已经改变在这里，在myAsyncRunnable的代码扩展的AsyncTask

@Override 
protected Void doInBackground(String... params) { 
fire(); 
return null; 
} 

public void fire() { 
     final ImageView image3 = (ImageView) gameactivity.findViewById(R.id.imageView3); 
     final int drawables[] = new int[] {R.drawable.fire1,R.drawable.fire2,R.drawable.fire3,R.drawable.fire4,R.drawable.fire5,R.drawable.fire6,R.drawable.fire7,R.drawable.fire8,R.drawable.fire9,R.drawable.fire10,R.drawable.fire11,R.drawable.fire12,R.drawable.fire13,R.drawable.fire14,R.drawable.fire15,R.drawable.fire16}; 
     for (int i=0;i<drawables.length;i++) { 
      final int j=i; 
      Runnable runnable = new Runnable() { 
       @Override 
       public void run() { 
        image3.setImageResource(drawables[j]); 
        Log.w("GAMEACTIVITY","image"+j); 
       } 
      }; 
      gameactivity.handler.postDelayed(runnable, 200*j); 
     } 
    } 

@Override 
protected void onPostExecute(Void result) { 
    Log.w("GAMEACTIVITY","ONPOSTEXECUTE"); 
    gameactivity.doPhotoTask(); 
}

在PhotoTask

@Override 
    protected Void doInBackground(Boolean... params) { 
     camera.takePicture(null,null, myPictureCallback_JPG); 
      Log.w("GAMEACTIVITY","TAKEPICTURE"); 

      return null; 
    }

我的日志猫

02-11 16:03:32.920: W/GAMEACTIVITY(7750): actionup 
02-11 16:03:33.010: W/GAMEACTIVITY(7750): image0 
02-11 16:03:33.010: W/GAMEACTIVITY(7750): ONPOSTEXECUTE 
02-11 16:03:33.030: E/QualcommCameraHardware(99): takePicture(479) 
02-11 16:03:33.100: E/QualcommCameraHardware(99): rawsize = 460800 cbcr offset =307200 
02-11 16:03:33.110: E/QualcommCameraHardware(99): takePicture: X 
02-11 16:03:33.110: W/GAMEACTIVITY(7750): TAKEPICTURE 
02-11 16:03:33.120: E/mm-camera(99): camera_ops_start, CAMERA_OPS_CAPTURE_AND_ENCODE mode 1 
02-11 16:03:33.350: W/GAMEACTIVITY(7750): image1 
02-11 16:03:33.490: W/GAMEACTIVITY(7750): image2 
02-11 16:03:33.780: W/GAMEACTIVITY(7750): image3 
02-11 16:03:33.880: W/GAMEACTIVITY(7750): image4 
02-11 16:03:34.110: W/GAMEACTIVITY(7750): image5 
02-11 16:03:34.250: W/GAMEACTIVITY(7750): image6 
02-11 16:03:34.490: W/GAMEACTIVITY(7750): image7 
02-11 16:03:34.680: W/GAMEACTIVITY(7750): image8 
02-11 16:03:34.880: W/GAMEACTIVITY(7750): image9 
02-11 16:03:35.050: W/GAMEACTIVITY(7750): image10 
02-11 16:03:35.110: E/QualcommCameraHardware(99): receiveRawPicture: E 
02-11 16:03:35.280: W/GAMEACTIVITY(7750): image11 
02-11 16:03:35.440: W/GAMEACTIVITY(7750): image12 
02-11 16:03:35.500: E/QualcommCameraHardware(99): address of Jpeg 0 encoded buf 1085800448 Jpeg Heap base 1085800448 
02-11 16:03:35.500: W/GAMEACTIVITY(7750): FIRST 
02-11 16:03:36.470: W/GAMEACTIVITY(7750): INTENT 
02-11 16:03:36.580: W/GAMEACTIVITY(7750): image13 
02-11 16:03:36.710: W/GAMEACTIVITY(7750): image14 
02-11 16:03:36.800: W/GAMEACTIVITY(7750): image15 
02-11 16:03:37.320: W/GAMEACTIVITY(7750): SURFACEDESTROYED

答

所以，问题是你计时未来可运行为未来的执行，然后从doInBackground返回 - 这immidiatly激活你onPostExecute功能。

解决您的问题的方法不是使用onPostExcute，而是使用您想要在所有其他Runnable之后运行的代码来计时另一个Runnable，因为它们都运行在同一个线程上，这可以解决您的问题。

我有问题。当我写“gameactivity.handler.postDelayed（runnable，200 * j）;”执行该行之后，在doBackground方法中运行200毫秒还是运行在外？ – morg 2013-02-11 16:44:12

http://developer.android.com/reference/android/os/Handler.html 看看PostDelayed。它会在gameactivity线程上运行（不在后台，如果你正在更新ui，这很好）。 – Raanan 2013-02-11 16:46:42

非常感谢你，我定时另一个runnable做doPhotoTask（） – morg 2013-02-11 16:54:49

答

试试这个小photoTask启动改变，它可能会帮助你。

Runnable runnable = new Runnable() { 
       @Override 
       public void run() { 
        image3.setImageResource(drawables[j]); 
        Log.w("GAMEACTIVITY","image"+j); 
      gameactivity.handler.postDelayed(this, 200*j); 
       } 
      }; 
      gameactivity.handler.postDelayed(runnable, 10);

Android：AsyncTask，onPostExecute在doInBackground完成之前启动

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