Ｃ＃关于网页抓取的有关问题

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Text.RegularExpressions;
using System.Data.SqlClient;
using System.Net;
using System.IO;

namespace GetQQData
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            tb_WebAddress.Text = "地址，自己替换";
        }
        //连接数据库字符串
        private static string strConn = "server=.;database=QQData;uid=xxx;password=xxx";

        private void btn_SaveAs_Click(object sender, EventArgs e)
        {
            string QQnum = "";
            int result = 0;
            //查询是否存在
            int count= 0;

            string HtmlStr = tb_HtmlContent.Text;
            StringBuilder sb = null;

            MatchCollection mc = GetValues(HtmlStr, "<li>", "</li>");
            for (int i = 0; i < mc.Count; i++)
            {
                try
                {
                    string tmpHtml = string.Empty;
                    tmpHtml = mc[i].Value;
                    QQnum = GetValue(tmpHtml, "qq=", "\"><img");

                    count = SelectQQ(QQnum);

                    if (count == 0)
                    {
                        sb = new StringBuilder();
                        sb.Append("insert into QQ(qqnum,addtime) values ('");
                        //sb.Append("QQnum");
                        //sb.Append("','");
                        sb.Append(QQnum);
                        sb.Append("','"+DateTime.Now+"')");

                        result += ExecuteNonQuery(sb.ToString());
                    }
                }
                catch
                { }
            }
            lbl_Over.Text = "保存了"+result+"个QQ";
        }

        //查询是否已经存在
        public int SelectQQ(string qqnum)
        {
            int result=0;
            string strSql = "select count(*) from QQ where qqnum='" + qqnum + "'";
            using (SqlConnection conn = new SqlConnection(strConn))
            {
                using (SqlCommand cmd = new SqlCommand(strSql, conn))
                {
                    try
                    {
                        conn.Open();
                        result = Convert.ToInt32(cmd.ExecuteScalar());
                    }

                    catch
                    {
                        result = 1;
                    }

                    finally
                    {
                        cmd.Dispose();
                        conn.Close();
                    }
                }
            }

            return result;
        }
        /// <summary>
        /// 正则全文匹配开始标签与结束标签之间的值,并放回数组
        /// </summary>
        /// <remarks>
        /// 方法名称：GetValues
        /// 创建人：
        /// 创建时间：2011-09-06
        /// Email：vochely@hotmail.com
        /// </remarks>
        /// <param name="strHtml">需要匹配的字符串</param>
        /// <param name="strStart">开始标签</param>
        /// <param name="strEnd">结束标签</param>
        /// <returns>返回开始标签与结束标签之间的值</returns>
        public static MatchCollection GetValues(string strHtml, string strStart, string strEnd)
        {
            MatchCollection result = null;

            try
            {
                Regex rg = new Regex("(?<=(" + strStart + "))[.\\s\\S]*?(?=(" + strEnd + "))", RegexOptions.Multiline | RegexOptions.Singleline);
                result = rg.Matches(strHtml);
            }

            catch
            {

            }

            return result;
        }

        /// <summary>
        /// 正则匹配开始标签与结束标签之间的值
        /// </summary>
        /// <remarks>
        /// 方法名称：GetValue
        /// 创建人：zt
        /// 创建时间：2011-09-06
        /// Email：vochely@hotmail.com
        /// </remarks>
        /// <param name="strHtml">需要匹配的字符串</param>
        /// <param name="strStart">开始标签</param>
        /// <param name="strEnd">结束标签</param>
        /// <returns>返回开始标签与结束标签之间的值</returns>
        public static string GetValue(string strHtml, string strStart, string strEnd)
        {
            string result = string.Empty;

            try
            {
                Regex rg = new Regex("(?<=(" + strStart + "))[.\\s\\S]*?(?=(" + strEnd + "))", RegexOptions.Multiline | RegexOptions.Singleline);
                result = rg.Match(strHtml).Value;
            }

            catch
            {

            }

            return result;
        }
        /// <summary>
        /// 执行增删改的对象,返回所影响的行数
        /// </summary>
        /// <remarks>
        /// 方法名称：ExecuteNonQuery
        /// 创建人：
        /// 创建时间：2011-09-06
        /// Email：vochely@hotmail.com
        /// </remarks>
        /// <param name="strSql">sql语句</param>
        /// <returns>返回 所影响的行数</returns>
        /// <connectionStrings>
       
        public static int ExecuteNonQuery(string strSql)
        {
            int result = 0;
            using (SqlConnection conn = new SqlConnection(strConn))
            {
                using (SqlCommand cmd = new SqlCommand(strSql, conn))
                {
                    try
                    {
                        conn.Open();
                        result = cmd.ExecuteNonQuery();
                    }

                    catch
                    {
                        result = 0;
                    }

                    finally
                    {
                        cmd.Dispose();
                        conn.Close();
                    }
                }
            }

            return result;
        }

        private void btn_EmptyContent_Click(object sender, EventArgs e)
        {
            tb_HtmlContent.Text = "";
            lbl_Over.Text = "";
        }

        private void btn_GetSoure_Click(object sender, EventArgs e)
        {
            string html = "";
            string HtmlUrl = tb_WebAddress.Text.ToString().Trim();
            html = GetHtml(HtmlUrl);
            tb_HtmlContent.Text = html;
        }

        /// <summary>
        /// 根据地址抓取Html
        /// ----------
        /// 
        /// 2011-09-06
        /// ----------
        /// </summary>
        /// <param name="url">抓取页面地址</param>
        /// <returns>抓取页面结果的源码</returns>
        public static string GetHtml(string url)
        {
            //根据Url地址获取当前地址的相应
            HttpWebResponse response = (HttpWebResponse)WebRequest.Create(url).GetResponse();
            //获取当前相应流
            Stream responseStream = response.GetResponseStream();
            //读取基础流文件
            StreamReader reader = new StreamReader(responseStream, Encoding.GetEncoding("UTF-8"));
            string strHtml = reader.ReadToEnd();
            //关闭基础流
            reader.Close();
            //关闭当前流的资源
            responseStream.Close();
            //关闭相应流
            response.Close();
            //返回页面源代码
            return strHtml;
        }

    }
}