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如果另一个 Activity 崩溃，Android 将返回到前一个 Activity

发布于 2024-12-07 16:24:30 字数 99 浏览 1 评论 0原文

如果另一个 Activity 导致抛出未处理的异常，是否有办法要求 Android 返回到我的应用程序中的上一个 Activity？

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谈情不如逗狗 2024-12-14 16:24:30

您可以尝试使用 Thread.setDefaultUncaughtExceptionHandler 当任何线程由于未处理的异常而死亡时接收通知。但我不确定 Dalvik 是否实现了该机制。您可能无法从 UncaughtExceptionHandler 启动另一个活动，因为文档没有提及线程/进程复活。

更新

好的。我对其进行了测试，现在我确信如果您的应用程序在 UI 线程中引发异常，您将无法使用上述技术返回到先前的 Activity。发生这种情况是因为该异常会导致应用程序主循环程序退出，因此您的应用程序将无法处理任何进一步的 UI 消息。

我发现实现您想要的效果的唯一可能方法是以下脏黑客：

public class MyApplication extends Application {

  @Override
  public void onCreate() {
    super.onCreate();
    while (true) {
      try {
        Log.i("MyLooper", "Starting my looper");
        Looper.loop();
      } catch (Exception e) {
        Log.e("MyLooper", "Caught the exception in UI thread, e:", e);
        showPreviousActivity();
      }
    }
  }

  private void showPreviousActivity() {
    // your implementation of showing the previous activity
  }   
}

并在 AndroidManifest.xml 中注册 MyApplication：

<application android:name=".MyApplication">
…

showPreviousActivity() 方法的实现取决于您。一种可能的解决方案是跟踪某个 ActivityTracker 类中当前的 Activity 实例，并从 showPreviousActivity 代码中调用当前活动的 finish() 方法。

You can try to use Thread.setDefaultUncaughtExceptionHandler to receive notification when any thread has died due to an unhandled exception. But I'm not sure about Dalvik implementation of that mechanism. It could be possible you would not be able to start another activity from the UncaughtExceptionHandler as the documentation says nothing about thread/process resurrection.

Update

Ok. I tested it and now I'm sure you will NOT be able to return to a previous Activity using the above technique if your application thrown an exception in the UI thread. This happens because that exception would cause application main looper to exit and thus your application would not be able to process any further UI messages.

The only possible way I've found to achieve what you want is the following dirty-hack:

public class MyApplication extends Application {

  @Override
  public void onCreate() {
    super.onCreate();
    while (true) {
      try {
        Log.i("MyLooper", "Starting my looper");
        Looper.loop();
      } catch (Exception e) {
        Log.e("MyLooper", "Caught the exception in UI thread, e:", e);
        showPreviousActivity();
      }
    }
  }

  private void showPreviousActivity() {
    // your implementation of showing the previous activity
  }   
}

And register MyApplication in your AndroidManifest.xml:

<application android:name=".MyApplication">
…

The implementation of the showPreviousActivity() method is up to you. One of the possible solution would be to keep track of the currently Activity instance in some ActivityTracker class and to call current activity finish() method from the showPreviousActivity code.

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