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, 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 = "mysoft";
            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();
        }

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;
        }

    }
}