C# post请求 HttpWebRequest

//body是要传递的参数,格式"roleId=1&uid=2"
//post的cotentType填写:
//"application/x-www-form-urlencoded"
//soap填写:"text/xml; charset=utf-8"

        public  string PostHttp(string url, string body, string contentType)

        {

            HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(url);

 

            httpWebRequest.ContentType = contentType;

            httpWebRequest.Method = "POST";

            httpWebRequest.Timeout = 20000;

 

            byte[] btBodys = Encoding.UTF8.GetBytes(body);

            httpWebRequest.ContentLength = btBodys.Length;

            httpWebRequest.GetRequestStream().Write(btBodys, 0, btBodys.Length);

 

            HttpWebResponse httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();

            StreamReader streamReader = new StreamReader(httpWebResponse.GetResponseStream());

            string responseContent = streamReader.ReadToEnd();

 

            httpWebResponse.Close();

            streamReader.Close();

            httpWebRequest.Abort();

            httpWebResponse.Close();

 

            return responseContent;

        }