判断后台service是否在运行

public static boolean isServiceRunning(Context mContext,String className) {

           boolean isRunning = false;
           ActivityManager activityManager = (ActivityManager)
           mContext.getSystemService(Context.ACTIVITY_SERVICE); 
           List<ActivityManager.RunningServiceInfo> serviceList 
                      = activityManager.getRunningServices(30);

           if (!(serviceList.size()>0)) {
               return false;
           }

           for (int i=0; i<serviceList.size(); i++) {
               if (serviceList.get(i).service.getClassName().equals(className) == true) {
                   isRunning = true;
                   break;
               }
           }
           return isRunning;
       }