抓取网页并获取指定内容段
1、发送HttpRequest请求。
2、接收HttpResponse返回的结果。得到特定页面的html源文件。
3、取出包含数据的那一部分源码。
4、根据html源码生成HtmlDocument，循环取出数据。
5、写入数据库。
程序如下：
//根据Url地址得到网页的html源码
private string GetWebContent(string Url)
{
string strResult="";
try
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
//声明一个HttpWebRequest请求
request.Timeout = 30000;
//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.GetEncoding("GB2312");
StreamReader streamReader = new StreamReader(streamReceive, encoding);
strResult = streamReader.ReadToEnd();
}
catch
{
MessageBox.Show("出错");
}
return strResult;
}
为了使用HttpWebRequest和HttpWebResponse，需填名字空间引用
using System.Net;
以下是程序具体实现过程：
private void button1_Click(object sender, EventArgs e)
{
//要抓取的URL地址
string Url = "http://list.mp3.baidu.com/topso/mp3topsong.html?id=1#top2";
//得到指定Url的源码
string strWebContent = GetWebContent(Url);
richTextBox1.Text = strWebContent;
//取出和数据有关的那段源码
int iBodyStart = strWebContent.IndexOf("<body", 0);
int iStart = strWebContent.IndexOf("歌曲TOP500", iBodyStart);
int iTableStart = strWebContent.IndexOf("<table", iStart);
int iTableEnd = strWebContent.IndexOf("</table>", iTableStart);
string strWeb = strWebContent.Substring(iTableStart, iTableEnd - iTableStart + 8);
//生成HtmlDocument
WebBrowser webb = new WebBrowser();
webb.Navigate("about:blank");
HtmlDocument htmldoc = webb.Document.OpenNew(true);
htmldoc.Write(strWeb);
HtmlElementCollection htmlTR = htmldoc.GetElementsByTagName("TR");
foreach (HtmlElement tr in htmlTR)
{
string strID = tr.GetElementsByTagName("TD")[0].InnerText;
string strName = SplitName(tr.GetElementsByTagName("TD")[1].InnerText, "MusicName");
string strSinger = SplitName(tr.GetElementsByTagName("TD")[1].InnerText, "Singer");
strID = strID.Replace(".", "");
//插入DataTable
AddLine(strID, strName, strSinger,"0");
string strID1 = tr.GetElementsByTagName("TD")[2].InnerText;
string strName1 = SplitName(tr.GetElementsByTagName("TD")[3].InnerText, "MusicName");
string strSinger1 = SplitName(tr.GetElementsByTagName("TD")[3].InnerText, "Singer");
//插入DataTable
strID1 = strID1.Replace(".", "");
AddLine(strID1, strName1, strSinger1,"0");
string strID2 = tr.GetElementsByTagName("TD")[4].InnerText;
string strName2 = SplitName(tr.GetElementsByTagName("TD")[5].InnerText, "MusicName");
string strSinger2 = SplitName(tr.GetElementsByTagName("TD")[5].InnerText, "Singer");
//插入DataTable
strID2 = strID2.Replace(".", "");
AddLine(strID2, strName2, strSinger2,"0");
}
//插入数据库
InsertData(dt);
dataGridView1.DataSource = dt.DefaultView;
}
以上引用来自:http://www.cnblogs.com/13590/archive/2007/06/14/407967.html
.NET2.0抓取网页全部链接
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Text.RegularExpressions;
using System.Net;
using System.IO;
using System.Collections;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
}
}
protected void Button1_Click(object sender, EventArgs e)
{
TextBox2.Text = "";
string web_url = this.TextBox1.Text;//"http://blog.csdn.net/21aspnet/"
string all_code = "";
HttpWebRequest all_codeRequest = (HttpWebRequest)WebRequest.Create(web_url);
WebResponse all_codeResponse = all_codeRequest.GetResponse();
StreamReader the_Reader = new StreamReader(all_codeResponse.GetResponseStream());
all_code = the_Reader.ReadToEnd();
the_Reader.Close();
ArrayList my_list = new ArrayList();
string p = @"http://([\w-]+\.)+[\w-]+(/[\w- ./?%&=]*)?";
Regex re = new Regex(p, RegexOptions.IgnoreCase);
MatchCollection mc = re.Matches(all_code);
for (int i = 0; i <= mc.Count - 1; i++)
{
bool _foo = false;
string name = mc[i].ToString();
foreach (string list in my_list)
{
if (name == list)
{
_foo = true;
break;
}
}//过滤
if (!_foo)
{
TextBox2.Text += name + "\n";
}
}
}
}
前台
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>抓取网页所有链接</title>
</head>
<body >
<form id="form1" runat="server">
<div>
<asp:TextBox ID="TextBox1" runat="server" Width="481px"></asp:TextBox>
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="提取" />
<br />
<asp:TextBox ID="TextBox2" runat="server" Height="304px" TextMode="MultiLine" Width="524px"></asp:TextBox></div>
</form>
</body>
</html>
点评：
精髓所在： string p = @http://([\w-]+\.)+[\w-]+(/[\w- ./?%&=]*)?;
http://www.cnblogs.com/ami/archive/2007/04/20/720621.aspx
