问在android phonegap应用程序中单击后退按钮时强制关闭

EN

ERROR/AndroidRuntime(23383): FATAL EXCEPTION: main
    ERROR/AndroidRuntime(23383): android.view.WindowManager
    $BadTokenException: Unable to add window -- token
    android.os.BinderProxy@48c59828 is not valid; is your activity
    running?
    at android.view.ViewRoot.setView(ViewRoot.java:505)
    at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:207)
    at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:121)
    at android.view.Window$LocalWindowManager.addView(Window.java:424)
    at android.app.Dialog.show(Dialog.java:259)
    at android.app.AlertDialog$Builder.show(AlertDialog.java:802)
    at com.phonegap.DroidGap$GapClient.onJsAlert(DroidGap.java:983)
    at android.webkit.CallbackProxy.handleMessage(CallbackProxy.java:531)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:123)
    at android.app.ActivityThread.main(ActivityThread.java:4632)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:521)
    at com.android.internal.os.ZygoteInit
    $MethodAndArgsCaller.run(ZygoteInit.java:871)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:629)
    at dalvik.system.NativeStart.main(Native Method)
    ERROR/(1364): Dumpstate > /data/log/dumpstate_app_error