public static bool GetValue(string json, string key, out string value)
{
  //解析失败的默认返回值
  value = "";
  JavaScriptSerializer serializer = new JavaScriptSerializer();
  try
  {
    Dictionary<string, object> obj_json = serializer.DeserializeObject(json) as Dictionary<string, object>;
    if (obj_json.ContainsKey(key))
    {
      value = serializer.Serialize(obj_json[key]);
      return true;
    }
    return false;
  }
  catch (Exception)
  {
    return false;
  }
}
public static bool GetValue(string json, int index, out string value)
{
  //解析失败的默认返回值
  value = "";
  JavaScriptSerializer serializer = new JavaScriptSerializer();
  try
  {
    object[] obj_json = serializer.DeserializeObject(json) as object[];
    if (obj_json.Length > index)
    {
      value = serializer.Serialize(obj_json[index]);
      return true;
    }
    return false;
  }
  catch (Exception)
  {
    return false;
  }
}