拦截 常按HOME键 但是会闪现一下任务管理器

public void onWindowFocusChanged(boolean hasFocus) {    super.onWindowFocusChanged(hasFocus);         Log.d("Focus debug", "Focus changed !");     if(!hasFocus) {        Log.d("Focus debug", "Lost focus !");         Intent closeDialog = new Intent(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);        closeDialog.putExtra("reason", "globalactions");//可避免关机对话框被关闭        sendBroadcast(closeDialog);    }}