【遇见Android bug】Unable to add window -- token android.os.BinderProxy@4396ecc8 is not valid; is your a

android.view.WindowManager$BadTokenException: Unable to add window -- token android.os.BinderProxy@4396ecc8 is not valid; is your activity running?
at android.view.ViewRootImpl.setView(ViewRootImpl.java:555)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:269)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
at android.app.Dialog.show(Dialog.java:289)
at com.sinvideo.joyshow.view.CfgCameraActivity.scanLeXianCamera(CfgCameraActivity.java:1594)
at com.sinvideo.joyshow.view.CfgCameraActivity$1.handleMessage(CfgCameraActivity.java:467)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5262)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:851)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:667)

at dalvik.system.NativeStart.main(Native Method)

这是一个比较常见的bug，出现bug的原因是AlertDialog需要依赖context呈现到前台，但是依赖的activity已被销毁，即context不复存在了。

解决的办法是创建一个boolean标记，在onPause()中置标记为false，在dialog.show()前判断标记是否为true即可。