C#中如何通过HTTP协议的不同请求方式获取数据

private string GetRequest(string url)

        {

           string content = "";

           Uri httpURL = new Uri(url);

           ///HttpWebRequest类继承于WebRequest，并没有自己的构造函数，需通过WebRequest的Creat方法 建立，并进行强制的类型转换  

            HttpWebRequest httpReq = (HttpWebRequest)WebRequest.Create(httpURL);

            httpReq.Credentials = new NetworkCredential("***", "****");

           ///通过HttpWebRequest的GetResponse()方法建立HttpWebResponse,强制类型转换  

            HttpWebResponse httpResp = (HttpWebResponse)httpReq.GetResponse();

           ///GetResponseStream()方法获取HTTP响应的数据流,并尝试取得URL中所指定的网页内容  

            ///若成功取得网页的内容，则以System.IO.Stream形式返回，若失败则产生ProtoclViolationException错 误。在此正确的做法应将以下的代码放到一个try块中处理。这里简单处理  

            Stream respStream = httpResp.GetResponseStream();

           ///返回的内容是Stream形式的，所以可以利用StreamReader类获取GetResponseStream的内容，并以  

            //StreamReader类的Read方法依次读取网页源程序代码每一行的内容，直至行尾（读取的编码格式：UTF8）  

            StreamReader respStreamReader = new StreamReader(respStream, Encoding.UTF8);

            content = respStreamReader.ReadToEnd();

           return content;

        }

       public string PostRequest(string Paras, string Url)

        {

           string result = "";

           HttpWebRequest request = WebRequest.Create(Url) as HttpWebRequest;

            request.Method = "POST";

            request.ContentType = "application/json";

           httpReq.Credentials = new NetworkCredential("***", "****");

           string data = Paras;

           byte[] byteData = UTF8Encoding.UTF8.GetBytes(data.ToString());

            request.ContentLength = byteData.Length;

 

           using (Stream postStream = request.GetRequestStream())

            {

                postStream.Write(byteData, 0, byteData.Length);

            }

 

           using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)

            {

               StreamReader reader = new StreamReader(response.GetResponseStream());

                result = reader.ReadToEnd();

            }

           return result;

        }

       public string DeleteRequest(string Url)

        {

           HttpWebRequest myrequest = (HttpWebRequest)WebRequest.Create(Url);

            myrequest.Method = "DELETE";

            httpReq.Credentials = new NetworkCredential("***", "****");

           HttpWebResponse myResponse = (HttpWebResponse)myrequest.GetResponse();

           StreamReader reader = new StreamReader(myResponse.GetResponseStream(),Encoding.UTF8);

           string Return = reader.ReadToEnd();

            reader.Close();

           return Return;

        }