c# 通过URl 获取返回的json格式数据

方法一

http://blog.csdn.net/angle_greensky110/article/details/52209497

    protected string GetJson(string url)
        {
            //访问https需加上这句话  
           // ServicePointManager.ServerCertificateValidationCallback = new System.Net.Security.RemoteCertificateValidationCallback(CheckValidationResult);
            //访问http（不需要加上面那句话）  
            WebClient wc = new WebClient();
            wc.Credentials = CredentialCache.DefaultCredentials;
            wc.Encoding = Encoding.UTF8;
            string returnText = wc.DownloadString(url);

            if (returnText.Contains("errcode"))
            {
                //可能发生错误  
            }
            //Response.Write(returnText);  
            return returnText;
        }  

　　方法二 （webservice）

  /// <summary>
        /// 通过Post方式获取数据
        /// </summary>
        /// <param name="url"></param>
        /// <param name="data">可为空</param>
        /// <returns></returns> 
 public string DoPost(string url, string data)
        {
            HttpWebRequest req = GetWebRequest(url, "POST");
            byte[] postData = Encoding.UTF8.GetBytes(data);
            Stream reqStream = req.GetRequestStream();
            reqStream.Write(postData, 0, postData.Length);
            reqStream.Close();
            HttpWebResponse rsp = (HttpWebResponse)req.GetResponse();
            Encoding encoding = Encoding.GetEncoding(rsp.CharacterSet);
            return GetResponseAsString(rsp, encoding);
        }

        public HttpWebRequest GetWebRequest(string url, string method)
        {
            HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
            req.ServicePoint.Expect100Continue = false;
            req.ContentType = "application/x-www-form-urlencoded;charset=utf-8";
            req.ContentType = "text/json";
            req.Method = method;
            req.KeepAlive = true;
            req.UserAgent = "guanyisoft";
            req.Timeout = 1000000;
            req.Proxy = null;
            return req;
        }

        public string GetResponseAsString(HttpWebResponse rsp, Encoding encoding)
        {
            StringBuilder result = new StringBuilder();
            Stream stream = null;
            StreamReader reader = null;
            try
            {
                // 以字符流的方式读取HTTP响应
                stream = rsp.GetResponseStream();
                reader = new StreamReader(stream, encoding);
                // 每次读取不大于256个字符，并写入字符串
                char[] buffer = new char[256];
                int readBytes = 0;
                while ((readBytes = reader.Read(buffer, 0, buffer.Length)) > 0)
                {
                    result.Append(buffer, 0, readBytes);
                }
            }
            finally
            {
                // 释放资源
                if (reader != null) reader.Close();
                if (stream != null) stream.Close();
                if (rsp != null) rsp.Close();
            }

            return result.ToString();
        }