C# Post方式传输报文，和处理响应

   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, , 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 = "mysoft";
             req.Timeout = ;
             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[];
                 int readBytes = ;
                 while ((readBytes = reader.Read(buffer, , buffer.Length)) > )
                 {
                     result.Append(buffer, , readBytes);
                 }
             }
             finally
             {
                 // 释放资源
                 if (reader != null) reader.Close();
                 if (stream != null) stream.Close();
                 if (rsp != null) rsp.Close();
             }

             return result.ToString();
         }

一个帮助类

result = _httpHelper.Url(url).Content(msg).Post();

using System.Net.Http;
using System.Net.Http.Headers;

namespace Common
{
    public  class HttpHelper
   {
        private readonly HttpClient _httpClient;
        private string _url;
        private string _content;

       public HttpHelper()
       {
           _httpClient = new HttpClient();
           _httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
        }
        public HttpHelper Url(string url)
       {
           _url = url;
           return this;
       }
        public HttpHelper Content(string content)
        {
            _content = content;
            return this;
        }
        public HttpHelper HeaderKeyValue(string key,string value)
        {
            if (_httpClient.DefaultRequestHeaders.Contains(key))
                _httpClient.DefaultRequestHeaders.Remove(key);
            _httpClient.DefaultRequestHeaders.Add(key, value);
            return this;
        }
        public string Post()
        {
            var content = new StringContent(_content);
            var response = _httpClient.PostAsync(_url,content).Result;
            return response.IsSuccessStatusCode ? response.Content.ReadAsStringAsync().Result : null;
        }
        public string Get()
        {
            var response = _httpClient.GetAsync(_url).Result;
            return response.IsSuccessStatusCode ? response.Content.ReadAsStringAsync().Result : null;
        }

    }
}