定时抓取网页，并保存到指定文件

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.IO;
using System.Net;

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

        Timer timer1 = new Timer();

        private void Form1_Load(object sender, EventArgs e)
        {

        }



        private void btnStop_Click(object sender, EventArgs e)
        {
            timer1.Stop();
            //Application.Exit();
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            timer1.Interval = int.Parse(txtInter.Text.Trim()) * 1000;
            timer1.Tick += new EventHandler(timer1_Tick);
            timer1.Start();
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            string DirName = "";
            string DirPath = txtDir.Text.ToString();
            string CapUrl = txtUrl.Text.Trim();
            HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(new Uri(CapUrl));
            HttpWebResponse webResponse = (HttpWebResponse)webRequest.GetResponse();
            StreamReader str = new StreamReader(webResponse.GetResponseStream(), Encoding.GetEncoding("gb2312"));

            string fileName = txtDir.Text.ToString().Substring(txtDir.Text.ToString().LastIndexOf("//") + 1);
              //判断选择的文件夹后面是否有文件名，如果没有则把所抓取网页的文件名加在所选的文件夹后面
            if (fileName == "" || !fileName.Contains(".html") || !fileName.Contains(".htm"))
            {
                string URLName = CapUrl.Substring(CapUrl.LastIndexOf("/") + 1);
                DirPath +="//"+URLName;

            }
             DirName = txtDir.Text.ToString().Substring(0, txtDir.Text.ToString().Length - fileName.Length);

            if (!Directory.Exists(DirName))
            {
                Directory.CreateDirectory(DirName);
            }
            using (FileStream fs = new FileStream(DirPath, FileMode.Create))
            {
                // 创建一个StreamWriter对象，使用UTF-8编码格式
                using (StreamWriter writer = new StreamWriter(fs, Encoding.GetEncoding("gb2312")))
                {
                    writer.Write(str.ReadToEnd());
                    writer.Close();
                }
            }


            str.Close();
            webResponse.Close();

        }

         //用folderBrowserDialog控件选择文件夹，必须先加一个按钮控件做为浏览按钮，一个
          // 文本框控件用于保存选择的文件夹路径
        private void btnBrowse_Click(object sender, EventArgs e)
        {
            if (folderBrowserDialog1.ShowDialog() == DialogResult.OK)
            {
                txtDir.Text = folderBrowserDialog1.SelectedPath;
            }
        }

    }
}