例如:
{"error_response":{"code":29,"msg":"Invalid app Key","sub_code":"isv.appkey-not-exists","request_id":"7vk7730y2ghu"}}
获取方式
var json1 = JObject.Parse(jsonStr)["error_response"]; //序列化成json
var code = json1["code"].Value<int>(); //获取json里面参数的值