本文实例为大家分享了基于C#实现网页爬虫的详细代码，供大家参考，具体内容如下
HTTP请求工具类：
功能：
1、获取网页html
2、下载网络图片
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace Utils
{
/// <summary>
/// HTTP请求工具类
/// </summary>
public class HttpRequestUtil
{
/// <summary>
/// 获取页面html
/// </summary>
public static string GetPageHtml( string url)
{
// 设置参数
HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
request.UserAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0)" ;
//发送请求并获取相应回应数据
HttpWebResponse response = request.GetResponse() as HttpWebResponse;
//直到request.GetResponse()程序才开始向目标网页发送Post请求
Stream responseStream = response.GetResponseStream();
StreamReader sr = new StreamReader(responseStream, Encoding.UTF8);
//返回结果网页（html）代码
string content = sr.ReadToEnd();
return content;
}
/// <summary>
/// Http下载文件
/// </summary>
public static void HttpDownloadFile( string url)
{
int pos = url.LastIndexOf( "/" ) + 1;
string fileName = url.Substring(pos);
string path = Application.StartupPath + "\\download" ;
if (!Directory.Exists(path))
{
Directory.CreateDirectory(path);
}
string filePathName = path + "\\" + fileName;
if (File.Exists(filePathName)) return ;
// 设置参数
HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
request.UserAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0)" ;
request.Proxy = null ;
//发送请求并获取相应回应数据
HttpWebResponse response = request.GetResponse() as HttpWebResponse;
//直到request.GetResponse()程序才开始向目标网页发送Post请求
Stream responseStream = response.GetResponseStream();
//创建本地文件写入流
Stream stream = new FileStream(filePathName, FileMode.Create);
byte [] bArr = new byte [1024];
int size = responseStream.Read(bArr, 0, ( int )bArr.Length);
while (size > 0)
{
stream.Write(bArr, 0, size);
size = responseStream.Read(bArr, 0, ( int )bArr.Length);
}
stream.Close();
responseStream.Close();
}
}
}
多线程爬取网页代码：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
using Utils;
namespace 爬虫
{
public partial class Form1 : Form
{
List<Thread> threadList = new List<Thread>();
Thread thread = null ;
public Form1()
{
InitializeComponent();
}
private void button1_Click( object sender, EventArgs e)
{
DateTime dtStart = DateTime.Now;
button3.Enabled = true ;
button2.Enabled = true ;
button1.Enabled = false ;
int page = 0;
int count = 0;
int personCount = 0;
lblPage.Text = "已完成页数：0" ;
int index = 0;
for ( int i = 1; i <= 10; i++)
{
thread = new Thread( new ParameterizedThreadStart( delegate ( object obj)
{
for ( int j = 1; j <= 10; j++)
{
try
{
index = (Convert.ToInt32(obj) - 1) * 10 + j;
string pageHtml = HttpRequestUtil.GetPageHtml( "http://tt.mop测试数据/c44/0/1_" + index.ToString() + ".html" );
Regex regA = new Regex( "<a[\\s]+class=\"J-userPic([^<>]*?)[\\s]+href=\"([^\"]*?)\"" );
Regex regImg = new Regex( "<p class=\"tc mb10\"><img[\\s]+src=\"([^\"]*?)\"" );
MatchCollection mc = regA.Matches(pageHtml);
foreach (Match match in mc)
{
int start = match.ToString().IndexOf( "href=\"" );
string url = match.ToString().Substring(start + 6);
int end = url.IndexOf( "\"" );
url = url.Substring(0, end);
if (url.IndexOf( "/" ) == 0)
{
string imgPageHtml = HttpRequestUtil.GetPageHtml( "http://tt.mop测试数据" + url);
personCount++;
lblPerson.Invoke( new Action( delegate () { lblPerson.Text = "已完成条数：" + personCount.ToString(); }));
MatchCollection mcImgPage = regImg.Matches(imgPageHtml);
foreach (Match matchImgPage in mcImgPage)
{
start = matchImgPage.ToString().IndexOf( "src=\"" );
string imgUrl = matchImgPage.ToString().Substring(start + 5);
end = imgUrl.IndexOf( "\"" );
imgUrl = imgUrl.Substring(0, end);
if (imgUrl.IndexOf( "http://i1" ) == 0)
{
try
{
HttpRequestUtil.HttpDownloadFile(imgUrl);
count++;
lblNum.Invoke( new Action( delegate ()
{
lblNum.Text = "已下载图片数" + count.ToString();
DateTime dt = DateTime.Now;
double time = dt.Subtract(dtStart).TotalSeconds;
if (time > 0)
{
lblSpeed.Text = "速度：" + (count / time).ToString( "0.0" ) + "张/秒" ;
}
}));
}
catch { }
Thread.Sleep(1);
}
}
}
}
}
catch { }
page++;
lblPage.Invoke( new Action( delegate () { lblPage.Text = "已完成页数：" + page.ToString(); }));
if (page == 100)
{
button1.Invoke( new Action( delegate () { button1.Enabled = true ; }));
MessageBox.Show( "完成！" );
}
}
}));
thread.Start(i);
threadList.Add(thread);
}
}
private void button2_Click( object sender, EventArgs e)
{
button1.Invoke( new Action( delegate ()
{
foreach (Thread thread in threadList)
{
if (thread.ThreadState == ThreadState.Suspended)
{
thread.Resume();
}
thread.Abort();
}
button1.Enabled = true ;
button2.Enabled = false ;
button3.Enabled = false ;
button4.Enabled = false ;
}));
}
private void Form1_FormClosing( object sender, FormClosingEventArgs e)
{
foreach (Thread thread in threadList)
{
thread.Abort();
}
}
private void button3_Click( object sender, EventArgs e)
{
foreach (Thread thread in threadList)
{
if (thread.ThreadState == ThreadState.Running)
{
thread.Suspend();
}
}
button3.Enabled = false ;
button4.Enabled = true ;
}
private void button4_Click( object sender, EventArgs e)
{
foreach (Thread thread in threadList)
{
if (thread.ThreadState == ThreadState.Suspended)
{
thread.Resume();
}
}
button3.Enabled = true ;
button4.Enabled = false ;
}
}
}
截图：
以上就是本文的全部内容，希望对大家的学习有所帮助。
dy("nrwz");