C# 发送和接受Get请求

    　　public static string HttpGet(string Url, string postDataStr)
        {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url + (postDataStr == string.Empty ? string.Empty : "?") + postDataStr);
            request.Method = "GET";
            request.ContentType = "text/html;charset=UTF-8";

            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            Stream myResponseStream = response.GetResponseStream();
            StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.GetEncoding("utf-8"));
            string retString = myStreamReader.ReadToEnd();
            myStreamReader.Close();
            myResponseStream.Close();

            return retString;
        }

string str1 = HttpUtility.UrlDecode(this.Request.QueryString.ToString(), Encoding.UTF8);