android 获取当前 activity

ActivityManager am = (ActivityManager) this .getSystemService(ACTIVITY_SERVICE);
  List<RunningTaskInfo> taskInfo = am.getRunningTasks(1);
  ComponentName componentInfo = taskInfo.get(0).topActivity;
  Log.d(WebServiceHelper.TAG, "CURRENT Activity ::" + taskInfo.get(0).topActivity.getClassName()+"   Package Name :  "+componentInfo.getPackageName());