C# 发送请求获得响应

两种封装方法：

#region 发送Http请求，获取返回结果
    /// <summary>
    /// 发送http请求，获取响应( Send HttpRequest and Get HttpResponse)
    /// </summary>
    /// <param name="RequestUrl">请求地址</param>        
    /// <param name="Params">http请求参数</param>
    /// <returns>响应内容</returns>
    private string SendRequestGetResponse(string RequestUrl, string Params)
    {
        HttpWebRequest HWRequest = null;
        string NewUrl = string.Empty;
        string RetCode = string.Empty;

        try
        {
            HWRequest = (HttpWebRequest)WebRequest.Create(RequestUrl);
            HWRequest.KeepAlive = true;
            HWRequest.Timeout = 30000;
            HWRequest.Method = "POST";
            HWRequest.ContentType = "application/x-www-form-urlencoded";

            HttpWebResponse HWResponse = null;
            byte[] reqParams = System.Text.Encoding.ASCII.GetBytes(Params);
            Stream st = HWRequest.GetRequestStream();
            st.Write(reqParams, 0, reqParams.Length);
            st.Flush();
            st.Close();

            HWResponse = (HttpWebResponse)HWRequest.GetResponse();
            Stream ResSt = HWResponse.GetResponseStream();
            StreamReader sr = new StreamReader(ResSt, System.Text.Encoding.UTF8);
            RetCode = sr.ReadToEnd();
            ResSt.Close();
            ResSt.Close();
            HWResponse.Close();
            ResSt.Dispose();
            sr.Dispose();
            st.Dispose();
        }
        catch
        {
            RetCode = string.Empty;
        }

        return RetCode;
    }
    #endregion


    #region 发送HTTP请求,获得响应
    /// <summary>
    /// 发送请求返回字符串
    /// </summary>
    /// <param name="url">请求地址</param>
    /// <param name="para">请求字符串</param>
    /// <param name="method">请求方式GET或POST</param>
    /// <returns></returns>
    private string SendRequestBackStr(string url, string para, string method)
    {
        string strResult = "";
        if (url == null || url == "")
            return null;
        if (method == null || method == "")
            method = "GET";
        #region GET方式
        if (method.ToUpper() == "GET")
        {
            try
            {
                HttpWebRequest wrq = (HttpWebRequest)WebRequest.Create(url + para);
                wrq.AllowAutoRedirect = false;
                HttpWebResponse wrp = (HttpWebResponse)wrq.GetResponse();
                if (((int)wrp.StatusCode) == 302)
                {
                    url = wrp.Headers["Location"];
                    if (url.IndexOf("?") < 0)
                    {
                        para = "&" + para.Substring(1, para.Length - 1);
                    }
                    wrq = (HttpWebRequest)WebRequest.Create(url + para);
                }
                System.IO.StreamReader sr = new System.IO.StreamReader(wrp.GetResponseStream(), System.Text.Encoding.GetEncoding("GB2312"));

                strResult = sr.ReadToEnd();
            }
            catch (Exception ex)
            {
                return ex.Message;
            }
        }
        #endregion
        #region POST方式
        if (method.ToUpper() == "POST")
        {
            if (para.Length > 0 && para.IndexOf('?') == 0)
            {
                para = para.Substring(1);
            }

            WebRequest req = WebRequest.Create(url);
            req.Method = "POST";
            req.ContentType = "application/x-www-form-urlencoded";
            StringBuilder UrlEncoded = new StringBuilder();
            Char[] reserved = { '?', '=', '&' };
            byte[] SomeBytes = null;
            if (para != null)
            {
                int i = 0, j;
                while (i < para.Length)
                {
                    j = para.IndexOfAny(reserved, i);
                    if (j == -1)
                    {
                        UrlEncoded.Append(HttpUtility.UrlEncode(para.Substring(i, para.Length - i), System.Text.Encoding.GetEncoding("GB2312")));
                        break;
                    }
                    UrlEncoded.Append(HttpUtility.UrlEncode(para.Substring(i, j - i), System.Text.Encoding.GetEncoding("GB2312")));
                    UrlEncoded.Append(para.Substring(j, 1));
                    i = j + 1;
                }
                SomeBytes = Encoding.Default.GetBytes(UrlEncoded.ToString());
                req.ContentLength = SomeBytes.Length;
                Stream newStream = req.GetRequestStream();
                newStream.Write(SomeBytes, 0, SomeBytes.Length);
                newStream.Close();
            }
            else
            {
                req.ContentLength = 0;
            }
            try
            {
                WebResponse result = req.GetResponse();
                Stream ReceiveStream = result.GetResponseStream();

                Byte[] read = new Byte[512];
                int bytes = ReceiveStream.Read(read, 0, 512);

                while (bytes > 0)
                {
                    // 注意：
                    // 下面假定响应使用 UTF-8 作为编码方式。
                    // 如果内容以 ANSI 代码页形式（例如，932）发送，则使用类似下面的语句：
                    //  Encoding encode = System.Text.Encoding.GetEncoding("shift-jis");
                    Encoding encode = System.Text.Encoding.GetEncoding("GB2312");
                    strResult += encode.GetString(read, 0, bytes);
                    bytes = ReceiveStream.Read(read, 0, 512);
                }

                return strResult;
            }
            catch (Exception ex)
            {
                return ex.Message;
            }
        }
        #endregion
        return strResult;
    }
    #endregion

第一种考虑到请求方式Method,get 或者 Post,第二段代码可根据情况删减。post时需要用stream流传递请求参数，get则不需要。