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
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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();
}
}
}
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多线程爬取网页代码：
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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.com/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.com" + 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;
}
}
}
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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。