.NET Http请求

using System;
using System.IO;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;

namespace FrameWork.Common.Web
{
    public class HttpHelper
    {
        /// <summary>
        /// 发起一个HTTP请求（以POST同步方式）
        /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="param">参数：json格式字符串</param>
        public static string HttpPost(string url, string param = "")
        {
            var request = (HttpWebRequest)WebRequest.Create(url);
            request.Method = "POST";
            request.ContentType = "application/json";
            request.Accept = "*/*";
            request.Timeout = 10000;
            request.AllowAutoRedirect = false;
            StreamWriter requestStream = null;
            WebResponse response = null;
            string responseStr = null;
            try
            {
                requestStream = new StreamWriter(request.GetRequestStream());
                requestStream.Write(param);
                requestStream.Close();
                response = request.GetResponse();
                if (response != null)
                {
                    var reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                    responseStr = reader.ReadToEnd();
                    reader.Close();
                }
            }
            catch (Exception e)
            {
                throw e;
            }
            finally
            {
                request = null;
                requestStream = null;
                response = null;
            }
            return responseStr;
        }

        /// <summary>
        /// get请求，同步方式
        /// </summary>
        public static string HttpGet(string url, string postDataStr)
        {
            var request = (HttpWebRequest)WebRequest.Create(url + (postDataStr == "" ? "" : "?") + postDataStr);
            request.Method = "GET";
            request.ContentType = "text/html;charset=UTF-8";

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

            return retString;
        }

        /// <summary>
        /// 发送短信，异步请求
　　　　 /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="jsonString">json字符串，手机号和短信内容必填</param>
        public static void SendMessage(string url, string jsonString)
        {
            var client = new HttpClient();
            HttpContent httpContext = new StringContent(jsonString, Encoding.UTF8);
            httpContext.Headers.ContentType = new MediaTypeHeaderValue("application/json");
            //await异步等待回应
            client.PostAsync(url, httpContext).ContinueWith(t =>
            {
                // Get HTTP response from completed task. 
                var response = t.Result;
                // Check that response was successful or throw exception 
                response.EnsureSuccessStatusCode();
                // Read response asynchronously as JsonValue and write out top facts for each country 
                response.Content.ReadAsStringAsync().ContinueWith(
                    readTask =>
                    {
                        Console.WriteLine(readTask.Result + " time:==>" + DateTime.Now);

                    });
            });
        }
    }
}