FLAG_ACTIVITY_REORDER_TO_FRONT之ANR问题(Android L)

最新推荐文章于 2025-05-26 14:01:37 发布

原创最新推荐文章于 2025-05-26 14:01:37 发布 · 318 阅读

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#android ANR

本文描述了一个关于Android应用在特定操作流程下发生冻结的问题及解决方案。问题发生在从ActivityB返回ActivityA并按下设备返回键时，应用会冻结10秒以上且不会调用onPause()和onDestroy()方法。解决办法是在目标Activity的onNewIntent中使用FLAG_ACTIVITY_NEW_TASK启动一个立即finish的TrickActivity。

Issue: https://code.google.com/p/android/issues/detail?id=169768

问题摘要：
===============================================================
1)The app starts with Activity A, which simply shows a button called "Launch B". 2)Press this button -- this executes startActivity(FLAG_ACTIVITY_REORDER_TO_FRONT, ActivityB.class). 3)Activity B becomes active, which do some UI and backhand loading operation on UI thread. 4)After pressing back from Activity B, OnBackPressed Of Activity B, this executes startActivity(FLAG_ACTIVITY_REORDER_TO_FRONT, ActivityA.class). 5)Activity A's onResume() is called as expected and everything looks fine (I can see Activity A content again). 6)Press the device's Back key and App freezes for around 10 seconds or more and comes out of application. Without calling onPause(), onDestroy(). (So it may be anr with certain logs) 7)Sometime or may be repeating same above step for 4-5 times it also unfortunately force close googlequicksearchbox

After looking at system logs: found some important logs:

E/ActivityManager( 958): Reason: Input dispatching timed out (Waiting because no window has focus but there is a focused application that may eventually add a window when it finishes starting up.)
===============================================================

解决方式(workaround):
在FLAG_ACTIVITY_REORDER_TO_FRONT的目标Activity的onNewIntent中用FLAG_ACTIVITY_NEW_TASK start一个创建即消失的activity

示例：


 @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);
         if ((intent.getFlags() & Intent.FLAG_ACTIVITY_REORDER_TO_FRONT) != 0 && Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
          Intent trickIntent = new Intent(context, TrickActivity.class);
         trickIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
         startActivity(trickIntent);
         }
    }

其中


public class TrickActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        finish();
    }

    @Override
    public void finish() {
        super.finish();
        // disable the animation
        overridePendingTransition(0, 0);
    }
}