在服务端发起一个Post请求

   /// <summary>
    /// 构造url的参数ajax的data值
    /// </summary>
    /// <param name="dic"></param>
    /// <returns></returns>
    public static string GetUrlStr(Dictionary<string, string> dic) {
        StringBuilder sb = new StringBuilder();
        foreach (var item in dic) {
            sb.AppendFormat("{0}={1}&", item.Key, item.Value);
        }
        string urlStr = sb.Remove(sb.Length - 1, 1).ToString();
        return urlStr;
    }

    /// <summary>
    /// 发送post请求
    /// </summary>
    /// <param name="postData"></param>
    /// <param name="postUrl"></param>
    /// <returns></returns>
    public static string SendHttpPostRequest(string postData,string postUrl) {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(postUrl);
        byte[] data = Encoding.GetEncoding("gbk").GetBytes(postData);
        request.Method = "POST";
        request.ContentType = "application/x-www-form-urlencoded";
        request.ContentLength = data.Length;
        using (Stream stream = request.GetRequestStream()) {
            stream.Write(data, 0, data.Length);
        }
        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        string responseString = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding("utf-8")).ReadToEnd();
        return responseString;
    }

    protected void Page_Load(object sender, EventArgs e) {
        Dictionary<string, string> test = new Dictionary<string, string>();
        test.Add("info", System.Web.HttpUtility.UrlEncode("笑话"));
        string paream = Utility.GetUrlStr(test);       
        string result = Utility.SendHttpPostRequest(paream, "http://www.tuling123.com/openapi/api?key=9d2ff29d44b54e55acadbf5643569584");
        Response.Write(result);
    }