C#發Get或Post請求來請求html頁面

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
using System.Web;
using System.Windows.Forms;

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            string url = "http://192.168.10.10/home.htm";
            string result = sendPost(url, "post");

            if (result=="操作超時")
            {
                MessageBox.Show("未連線到列印伺服器");
            }
            else if (result.Contains(@"<td>Printer Status</td>"))
            {
                string td2 = GetStr(result, @"<td>Printer Status</td>", 41);
                string strPrinterStatus = td2.Substring(29, 8).Trim('<');

                MessageBox.Show(strPrinterStatus);
            }
        }


        /// <summary>
        /// 擷取字串中指定標籤內的內容
        /// </summary>
        /// <param name="Content">需要擷取的字串</param>
        /// <param name="start">開始標籤</param>
        /// <param name="end">結束標籤</param>
        /// <returns></returns>
        public string GetStr(string Content, string start, int length)
        {
            var posStart = Content.IndexOf(start);
            return Content.Substring(posStart, length);
        }


        /// <summary>
        /// Http (GET/POST)
        /// </summary>
        /// <param name="url">請求URL</param>
        /// <param name="method">請求方法</param>
        /// <returns>響應內容</returns>
        static string sendPost(string url, string method)
        {
            if (method.ToLower() == "post")
            {
                HttpWebRequest req = null;
                HttpWebResponse rsp = null;
                System.IO.Stream reqStream = null;
                try
                {
                    req = (HttpWebRequest)WebRequest.Create(url);
                    req.Method = method;
                    req.KeepAlive = false;
                    req.ProtocolVersion = HttpVersion.Version10;
                    req.Timeout = 5000;
                    req.ContentType = "application/x-www-form-urlencoded;charset=utf-8";
                    reqStream = req.GetRequestStream();
                    rsp = (HttpWebResponse)req.GetResponse();
                    Encoding encoding = Encoding.GetEncoding(rsp.CharacterSet);
                    return GetResponseAsString(rsp, encoding);
                }
                catch (Exception ex)
                {
                    return ex.Message;
                }
                finally
                {
                    if (reqStream != null) reqStream.Close();
                    if (rsp != null) rsp.Close();
                }
            }
            else
            {
                //建立請求
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);

                //GET請求
                request.Method = "GET";
                request.ReadWriteTimeout = 5000;
                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"));

                //返回內容
                string retString = myStreamReader.ReadToEnd();
                return retString;
            }
        }

        /// <summary>
        /// 組裝普通文字請求引數。
        /// </summary>
        /// <param name="parameters">Key-Value形式請求引數字典</param>
        /// <returns>URL編碼後的請求資料</returns>
        static string BuildQuery(IDictionary<string, string> parameters, string encode)
        {
            StringBuilder postData = new StringBuilder();
            bool hasParam = false;
            IEnumerator<KeyValuePair<string, string>> dem = parameters.GetEnumerator();
            while (dem.MoveNext())
            {
                string name = dem.Current.Key;
                string value = dem.Current.Value;
                // 忽略引數名或引數值為空的引數
                if (!string.IsNullOrEmpty(name))//&& !string.IsNullOrEmpty(value)
                {
                    if (hasParam)
                    {
                        postData.Append("&");
                    }
                    postData.Append(name);
                    postData.Append("=");
                    if (encode == "gb2312")
                    {
                        postData.Append(HttpUtility.UrlEncode(value, Encoding.GetEncoding("gb2312")));
                    }
                    else if (encode == "utf8")
                    {
                        postData.Append(HttpUtility.UrlEncode(value, Encoding.UTF8));
                    }
                    else
                    {
                        postData.Append(value);
                    }
                    hasParam = true;
                }
            }
            return postData.ToString();
        }

        /// <summary>
        /// 把響應流轉換為文字。
        /// </summary>
        /// <param name="rsp">響應流物件</param>
        /// <param name="encoding">編碼方式</param>
        /// <returns>響應文字</returns>
        static string GetResponseAsString(HttpWebResponse rsp, Encoding encoding)
        {
            System.IO.Stream stream = null;
            StreamReader reader = null;
            try
            {
                // 以字元流的方式讀取HTTP響應
                stream = rsp.GetResponseStream();
                reader = new StreamReader(stream, encoding);
                return reader.ReadToEnd();
            }
            finally
            {
                // 釋放資源
                if (reader != null) reader.Close();
                if (stream != null) stream.Close();
                if (rsp != null) rsp.Close();
            }
        }

    }
}