public class RestClient
    {
        private string BaseUri;
        public RestClient(string baseUri)
        {
            this.BaseUri = baseUri;
        }

        #region Delete方式
        public string HttpDelete(string data, string uri)
        {
            return CommonHttpRequest(data, uri, "DELETE");
        }

        public string Delete(string uri)
        {
            //Web访问对象64
            string serviceUrl = string.Format("{0}/{1}", this.BaseUri, uri);
            HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(serviceUrl);
            myRequest.Method = "DELETE";
            // 获得接口返回值68
            HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse();
            StreamReader reader = new StreamReader(myResponse.GetResponseStream(), Encoding.UTF8);
            //string ReturnXml = HttpUtility.UrlDecode(reader.ReadToEnd());
            string ReturnXml = reader.ReadToEnd();
            reader.Close();
            myResponse.Close();
            return ReturnXml;
        }
        #endregion

        #region Put方式
        public string Put(string data, string uri)
        {
            return CommonHttpRequest(data, uri, "PUT");
        }
        #endregion


        #region Patch方式
        public string Patch(string data, string uri)
        {
            return CommonHttpRequest(data, uri, "Patch");
        }
        #endregion

        #region POST方式实现

        public string Post(string data, string uri)
        {
            return CommonHttpRequest(data, uri, "POST");
        }

        public string CommonHttpRequest(string data, string uri, string type)
        {
            //Web访问对象，构造请求的url地址
            string serviceUrl = string.Format("{0}/{1}", this.BaseUri, uri);

            //构造http请求的对象
            HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(serviceUrl);
            //转成网络流
            byte[] buf = System.Text.Encoding.GetEncoding("UTF-8").GetBytes(data);
            //设置
            myRequest.Method = type;
            myRequest.ContentLength = buf.Length;
            myRequest.ContentType = "application/json";
            myRequest.MaximumAutomaticRedirections = 1;
            myRequest.AllowAutoRedirect = true;
            // 发送请求
            Stream newStream = myRequest.GetRequestStream();
            newStream.Write(buf, 0, buf.Length);
            newStream.Close();
            // 获得接口返回值
            HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse();
            StreamReader reader = new StreamReader(myResponse.GetResponseStream(), Encoding.UTF8);
            string ReturnXml = reader.ReadToEnd();
            reader.Close();
            myResponse.Close();
            return ReturnXml;
        }
        #endregion

        #region GET方式实现
        public string Get(string uri)
        {
            //Web访问对象64
            string serviceUrl = string.Format("{0}/{1}", this.BaseUri, uri);

            //构造一个Web请求的对象
            HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(serviceUrl);
            // 获得接口返回值68
            //获取web请求的响应的内容
            HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse();

            //通过响应流构造一个StreamReader
            StreamReader reader = new StreamReader(myResponse.GetResponseStream(), Encoding.UTF8);
            //string ReturnXml = HttpUtility.UrlDecode(reader.ReadToEnd());
            string ReturnXml = reader.ReadToEnd();
            reader.Close();
            myResponse.Close();
            return ReturnXml;
        }
        #endregion
    }

参考来源

C# 中经常用到的HTTP请求类，已封装get,post，delete,put，Patch