C#post方法

post方法
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Web;

namespace Demo
{
    public class MyPostGetHelper
    {
        public static string PostWebRequest(string postUrl, string paramData, Encoding dataEncode, string header = "")
        {
            string ret = string.Empty;
            try
            {
                if (dataEncode == null)
                    dataEncode = Encoding.UTF8;

                byte[] byteArray = dataEncode.GetBytes(paramData); //转化
                HttpWebRequest webReq = (HttpWebRequest)WebRequest.Create(new Uri(postUrl));
                webReq.Method = "POST";
                webReq.ContentType = "application/json";

                webReq.Headers.Add("Session-Key", header);

                webReq.ContentLength = byteArray.Length;
                Stream newStream = webReq.GetRequestStream();
                newStream.Write(byteArray, 0, byteArray.Length);//写入参数
                newStream.Close();
                HttpWebResponse response = (HttpWebResponse)webReq.GetResponse();
                var c = response.GetResponseStream();
                StreamReader sr = new StreamReader(c, Encoding.UTF8);

                Char[] read = new Char[4000];
                int count = sr.Read(read, 0, read.Length);

                while (count > 0)
                { 
                    String str = new String(read, 0, count);
                    ret += str;

                    count = sr.Read(read, 0, read.Length);
                }

                sr.Close();
                response.Close();
                newStream.Close();

            }
            catch (Exception ex)
            {
                throw;
            }
            return ret;
        }

    }
}