C# 发送HttpWebRequest，得到HttpWebResponse

using System;
using System.IO;
using System.Net;
using System.Text;
using System.Web;

namespace JasonLibrary
{
    public class HttpHelpler
    {
        public string Url { get; set; }
        public string Data { get; set; }

        public HttpHelpler(string url)
        {
            this.Url = url;
        }

        public HttpHelpler(string url, string data)
        {
            this.Url = url;
            this.Data = data;
        }

        public string ExecutePost()
        {
            try
            {
                HttpWebRequest myRequest = HttpWebRequest.Create(Url) as HttpWebRequest;
                myRequest.Method = "POST";
                myRequest.ContentType = "application/json;charset=UTF-8";
                myRequest.ReadWriteTimeout = 30000;

                byte[] data = Encoding.UTF8.GetBytes(Data);
                myRequest.ContentLength = data.Length;
                Stream myStream = myRequest.GetRequestStream();
                myStream.Write(data, 0, data.Length);
                myStream.Close();

                HttpWebResponse myResponse = myRequest.GetResponse() as HttpWebResponse;
                StreamReader sr = new StreamReader(myResponse.GetResponseStream(), Encoding.UTF8);
                string res = sr.ReadToEnd();
                return res;
            }
            catch 
            {
                return null;
            }
        }

        public string ExecuteGet()
        {
            HttpWebRequest myRequest = HttpWebRequest.Create(Url) as HttpWebRequest;
            myRequest.Method = "GET";
            myRequest.ReadWriteTimeout = 30000;

            HttpWebResponse myResponse = null;
            try
            {
                myResponse = myRequest.GetResponse() as HttpWebResponse;
                StreamReader sr = new StreamReader(myResponse.GetResponseStream(), Encoding.UTF8);
                string res = sr.ReadToEnd();
                return res;
            }
            catch (WebException ex)
            {
                myResponse = ex.Response as HttpWebResponse;
                using (Stream errData = myResponse.GetResponseStream())
                {
                    using (StreamReader sr = new StreamReader(errData))
                    {
                        string res = sr.ReadToEnd();
                        return res;
                    }
                }
            }
        }
    }
}