得到手机当前显示的activity的名字

    /**
     * @return 手机当前的activity
     */
     String getRunningActivityName(){        
        ActivityManager activityManager=(ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
        String runningActivity=activityManager.getRunningTasks(1).get(0).topActivity.getClassName();
        return runningActivity;               
    }