Dialog显示引起的问题 Activity has leaked window DecorView@5704632[] that was originally added here

dialog显示引起的界面无法打开的问题，报错信息如下：

1. 03-08 18:02:48.521: E/WindowManager(6340): Activity com.linc.megatron.activity.ExamActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@40568ea8 that was originally added here  
2. 03-08 18:02:48.521: E/WindowManager(6340): android.view.WindowLeaked: Activity com.linc.megatron.activity.ExamActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@40568ea8 that was originally added here  
3. 03-08 18:02:48.521: E/WindowManager(6340):  at android.view.ViewRoot.(ViewRoot.java:264)  
4. 03-08 18:02:48.521: E/WindowManager(6340):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148)  
5. 03-08 18:02:48.521: E/WindowManager(6340):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)  
6. 03-08 18:02:48.521: E/WindowManager(6340):  at android.view.Window$LocalWindowManager.addView(Window.java:424)  
7. 03-08 18:02:48.521: E/WindowManager(6340):  at android.app.Dialog.show(Dialog.java:241)  
8. 03-08 18:02:48.521: E/WindowManager(6340):  at com.linc.megatron.base.BackKeyActivity.showDialog(BackKeyActivity.java:76)  
9. 03-08 18:02:48.521: E/WindowManager(6340):  at com.linc.megatron.base.BackKeyActivity.onKeyDown(BackKeyActivity.java:62)  
10. 03-08 18:02:48.521: E/WindowManager(6340):  at android.view.KeyEvent.dispatch(KeyEvent.java:1256)  
11. 03-08 18:02:48.521: E/WindowManager(6340):  at android.app.Activity.dispatchKeyEvent(Activity.java:2078)  
12. 03-08 18:02:48.521: E/WindowManager(6340):  at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1709)  
13. 03-08 18:02:48.521: E/WindowManager(6340):  at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:2628)  
14. 03-08 18:02:48.521: E/WindowManager(6340):  at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2603)  
15. 03-08 18:02:48.521: E/WindowManager(6340):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1875)  
16. 03-08 18:02:48.521: E/WindowManager(6340):  at android.os.Handler.dispatchMessage(Handler.java:99)  
17. 03-08 18:02:48.521: E/WindowManager(6340):  at android.os.Looper.loop(Looper.java:123)  
18. 03-08 18:02:48.521: E/WindowManager(6340):  at android.app.ActivityThread.main(ActivityThread.java:3687)  
19. 03-08 18:02:48.521: E/WindowManager(6340):  at java.lang.reflect.Method.invokeNative(Native Method)  
20. 03-08 18:02:48.521: E/WindowManager(6340):  at java.lang.reflect.Method.invoke(Method.java:507)  
21. 03-08 18:02:48.521: E/WindowManager(6340):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)  
22. 03-08 18:02:48.521: E/WindowManager(6340):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)  
23. 03-08 18:02:48.521: E/WindowManager(6340):  at dalvik.system.NativeStart.main(Native Method)

显然，我用Dialog确认是否退出，但是activity销毁后并没有处理Dialog的退出。

解决办法：

只需要在activity销毁时关闭Dialog就好。

@Override
protected void onDestroy() {
    if(mDialog != null) {
        mDialog.dismiss();
    }
    super.onDestroy();
}