代码如下:

//提取产品列表页中产品最终页的网页 
private void button1_Click(object sender, EventArgs e) 
{ 
if (textBox1.Text.Trim() == "" || textBox2.Text.Trim() == "") 
{ 
MessageBox.Show("网址和域名不能为空！", "信息提示", MessageBoxButtons.OK, MessageBoxIcon.Information); 
return; 
} 
try 
{ 
string Html = inc.GetHtml("http://study.pctoday.net.cn"); 
//ArrayList al = inc.GetMatchesStr(Html, "<a[^>]*?>.*?</a>"); 
ArrayList al = inc.GetMatchesStr(Html, @"href\s*=\s*(?:[\'\""\s](?<1>[^\""\']*)[\'\""])");//提取链接 

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StringBuilder sb = new StringBuilder(); 
foreach (object var in al) 
{ 
string a = var.ToString().Replace("\"", "").Replace("'", ""); 
a = Regex.Replace(a, "href=", "", RegexOptions.IgnoreCase | RegexOptions.Multiline); 
if (a.StartsWith("/")) 
a = textBox2.Text.Trim() + a; 
if (!a.StartsWith("http://")) 
a = "http://" + a; 
sb.Append(a + "\r\n"); 
} 
textBox5.Text = sb.ToString();//把提取到网址

MessageBox.Show("共提取" + al.Count.ToString() + "个链接", "信息提示", MessageBoxButtons.OK, MessageBoxIcon.Information);

}
catch (Exception err)
{
MessageBox.Show("提取出错！原因：" + err.Message, "信息提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
}

}

//把采集的产品页面html代码进行字符串处理，提取需要的代码，最后保存到本地一个access数据库中，同时提取产品图片地址并自动现在图片到本地images文件夹下

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
//填充产品表
Database.ExecuteNonQuery("delete from Tb_Product");
DataTable dt2 = new DataTable();
OleDbConnection conn = new OleDbConnection(Database.ConnectionStrings);
OleDbDataAdapter da = new OleDbDataAdapter("select * from Tb_Product", conn);
OleDbCommandBuilder cb = new OleDbCommandBuilder(da);
da.Fill(dt2);
dt2.Rows.Clear();

BackgroundWorker worker = (BackgroundWorker)sender;//这个是做一个进度条

string[] Urls = textBox5.Text.Trim().ToLower().Replace("\r\n", ",").Split(',');
DataTable dt = new DataTable();
StringBuilder ErrorStr = new StringBuilder();
string html = "", ImageDir = AppDomain.CurrentDomain.BaseDirectory + "Images\\";

//循环每次采集网址
for (int i = 0; i < Urls.Length; i++)
{
try
{
if (!worker.CancellationPending)
{
if (Urls[i] == "")
return;
html = inc.GetHtml(Urls[i]);//获取该url的html代码
DataRow NewRow = dt2.NewRow();

//产品名
string ProductName = html.Substring(html.IndexOf("<title>") + 7);
NewRow["ProductName"] = ProductName.Remove(ProductName.IndexOf("</title>")).Trim();

//产品编号
NewRow["ModelId"] = NewRow["ProductName"].ToString().Substring(NewRow["ProductName"].ToString().IndexOf("Model:") + 6).Trim();

//产品介绍，这些都是根据不同网站的html做相应的修改
string Introduce = html.Substring(html.IndexOf("Product Details") + 26);
Introduce = Introduce.Remove(Introduce.IndexOf("</table>") + 8).Trim()

NewRow["Introduce"] = Introduce;

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//下载图片
string ProductImage = html.Substring(html.IndexOf("align=center><img") + 17);
ProductImage = textBox2.Text.Trim() + ProductImage.Substring(ProductImage.IndexOf("src=\"") + 5);
ProductImage = ProductImage.Remove(ProductImage.IndexOf("\""));
try
{
inc.DownFile(ProductImage, ImageDir + ProductImage.Substring(ProductImage.LastIndexOf("/") + 1));
}
catch (Exception)
{
ErrorStr.Append("下载图片失败，图片地址：" + ImageDir + ProductImage.Substring(ProductImage.LastIndexOf("/") + 1) + "\r\n");
}

dt2.Rows.Add(NewRow);

//Thread.Sleep(100);
worker.ReportProgress((i + 1) * 100 / Urls.Length, i);
toolStripStatusLabel1.Text = "处理进度:" + (i + 1).ToString() + "/" + Urls.Length.ToString();//进度条
}

}
catch (Exception err)
{
ErrorStr.Append("采集错误：" + err.Message + ";网址：" + Urls[i] + "\r\n");
}
}
da.Update(dt2);
DataBind(dt2);
ShowError(ErrorStr.ToString());
}

/// <summary>
/// ASPX页面生成静态Html页面，作者：郑少群
/// </summary>
public static string GetHtml(string url)
{
StreamReader sr = null;
string str = null;
//读取远程路径
WebRequest request = WebRequest.Create(url);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
sr = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding(response.CharacterSet));
str = sr.ReadToEnd();
sr.Close();
return str;
}

// 提取HTML代码中的网址
public static ArrayList GetMatchesStr(string htmlCode, string strRegex)
{
ArrayList al = new ArrayList();

Regex r = new Regex(strRegex, RegexOptions.IgnoreCase | RegexOptions.Multiline);
MatchCollection m = r.Matches(htmlCode);

for (int i = 0; i < m.Count; i++)
{
bool rep = false;
string strNew = m[i].ToString();

// 过滤重复的URL
foreach (string str in al)
{
if (strNew == str)
{
rep = true;
break;
}
}

if (!rep) al.Add(strNew);
}

al.Sort();

return al;
}

public static void DownFile(string Url, string Path)
{

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Stream stream = response.GetResponseStream();
long size = response.ContentLength;
//创建文件流对象
using (FileStream fs = new FileStream(Path, FileMode.OpenOrCreate, FileAccess.Write))
{
byte[] b = new byte[1025];
int n = 0;
while ((n = stream.Read(b, 0, 1024)) > 0)
{
fs.Write(b, 0, n);
}
}
}