今天调试程序时log中突然打印这样的错误，但是程序并没有crash，为了不放过一个错误，我决定调查一下。
当时是离开一个activity，然后提示是否退出此界面，接下来就打印此错误：
03-08 18:02:48.521: E/WindowManager(6340): Activity com.linc.megatron.activity.ExamActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@40568ea8 that was originally added here 03-08 18:02:48.521: E/WindowManager(6340): android.view.WindowLeaked: Activity com.linc.megatron.activity.ExamActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@40568ea8 that was originally added here 03-08 18:02:48.521: E/WindowManager(6340): at android.view.ViewRoot.<init>(ViewRoot.java:264) 03-08 18:02:48.521: E/WindowManager(6340): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148) 03-08 18:02:48.521: E/WindowManager(6340): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91) 03-08 18:02:48.521: E/WindowManager(6340): at android.view.Window$LocalWindowManager.addView(Window.java:424) 03-08 18:02:48.521: E/WindowManager(6340): at android.app.Dialog.show(Dialog.java:241) 03-08 18:02:48.521: E/WindowManager(6340): at com.linc.megatron.base.BackKeyActivity.showDialog(BackKeyActivity.java:76) 03-08 18:02:48.521: E/WindowManager(6340): at com.linc.megatron.base.BackKeyActivity.onKeyDown(BackKeyActivity.java:62) 03-08 18:02:48.521: E/WindowManager(6340): at android.view.KeyEvent.dispatch(KeyEvent.java:1256) 03-08 18:02:48.521: E/WindowManager(6340): at android.app.Activity.dispatchKeyEvent(Activity.java:2078) 03-08 18:02:48.521: E/WindowManager(6340): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1709) 03-08 18:02:48.521: E/WindowManager(6340): at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:2628) 03-08 18:02:48.521: E/WindowManager(6340): at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2603) 03-08 18:02:48.521: E/WindowManager(6340): at android.view.ViewRoot.handleMessage(ViewRoot.java:1875) 03-08 18:02:48.521: E/WindowManager(6340): at android.os.Handler.dispatchMessage(Handler.java:99) 03-08 18:02:48.521: E/WindowManager(6340): at android.os.Looper.loop(Looper.java:123) 03-08 18:02:48.521: E/WindowManager(6340): at android.app.ActivityThread.main(ActivityThread.java:3687) 03-08 18:02:48.521: E/WindowManager(6340): at java.lang.reflect.Method.invokeNative(Native Method) 03-08 18:02:48.521: E/WindowManager(6340): at java.lang.reflect.Method.invoke(Method.java:507) 03-08 18:02:48.521: E/WindowManager(6340): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 03-08 18:02:48.521: E/WindowManager(6340): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) 03-08 18:02:48.521: E/WindowManager(6340): at dalvik.system.NativeStart.main(Native Method)
解决办法：
知道了问题所在就容易解决问题了。只需要在activity销毁时关闭Dialog就好。
@Override
protected void onDestroy() {
if(mDialog != null) {
mDialog.dismiss();
}
super.onDestroy();
}