C#访问url地址并返回数据

  public partial class Form1 : Form
    {
        static bool isSelect = false;
        public Form1()
        {
            InitializeComponent();
            textBox3.Enabled = textBox1.Enabled = false;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (isSelect == false)
            {
                textBox2.Text = GetResponseData(textBox1.Text.Trim().Replace("\n", "").Replace("\r", ""), textBox3.Text.Trim().Replace("\r", "").Replace("\n", ""));
            }
            else
            {
                textBox2.Text = HttpGet(textBox1.Text.Trim().Replace("\n", "").Replace("\r", ""));
            }

            //textBox2.Text = HttpGet(textBox1.Text.Trim());
        }

        public string HttpGet(string Url)
        {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
            request.Method = "GET";
            request.ContentType = "text/html;charset=UTF-8";

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

            return retString;
        }

        public string GetResponseData(string JSONData, string Url)
        {
            byte[] bytes = Encoding.UTF8.GetBytes(JSONData);
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
            request.Method = "POST";
            request.ContentLength = bytes.Length;
            request.ContentType = "text/xml";
            Stream reqstream = request.GetRequestStream();
            reqstream.Write(bytes, , bytes.Length);

            //声明一个HttpWebRequest请求
            request.Timeout = ;
            //设置连接超时时间
            request.Headers.Set("Pragma", "no-cache");
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            Stream streamReceive = response.GetResponseStream();
            Encoding encoding = Encoding.UTF8;

            StreamReader streamReader = new StreamReader(streamReceive, encoding);
            string strResult = streamReader.ReadToEnd();
            streamReceive.Dispose();
            streamReader.Dispose();

            return strResult;
        }

        private void label2_Click(object sender, EventArgs e)
        {

        }

        private void radioButton1_Click(object sender, EventArgs e)
        {
            isSelect = true;
            label1.Text = "url";
            textBox1.Enabled = true;
            textBox3.Enabled = false;
        }

        private void radioButton2_CheckedChanged(object sender, EventArgs e)
        {
            isSelect = false;
            label1.Text = "json";
            textBox3.Enabled = textBox1.Enabled = true;
        }
    }