android判断一个Service是否存在

public static boolean isServiceExisted(Context context, String className) {
ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
List<ActivityManager.RunningServiceInfo> serviceList = activityManager.getRunningServices(Integer.MAX_VALUE);
if(!(serviceList.size() > 0)) {
return false;
}
for(int i = 0; i < serviceList.size(); i++) {
RunningServiceInfo serviceInfo = serviceList.get(i);
ComponentName serviceName = serviceInfo.service;
if(serviceName.getClassName().equals(className)) {
return true;
}
} 
return false;

}