网页抓取数据并分析，特别包括分页数据的抓取。

包括8个按钮，每个按钮下的代码都可运行（第5、6个可能需要调试一下）。

有基本的页面抓取，不含分页数据的；

有含分页数据，且【下一页】的链接是网址的；

有含分页数据，且【下一页】的链接是__doPostBack；

有含分页数据，且【下一页】的属性是.gif，可通过F12找到href的。

参考网址：http://www.cnblogs.com/ceachy/articles/CSharp_Retrive_Page_Document.html

http://www.cnblogs.com/ghfsusan/archive/2010/05/26/1744820.html

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 WindowsFormsApplication1{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();        }        //private void button1_Click(object sender, EventArgs e)        //{        //    MessageBox.Show("hello world.");        //}        //WebBrowser web1 = new WebBrowser();         //web1.Navigate("http://www.xjflcp.com/ssc/");         //web.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(web_DocumentCompleted);         //void web_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)         //{         //    WebBrowser web = (WebBrowser)sender;         //    HtmlElementCollection ElementCollection = web.Document.GetElementsByTagName("Table");         //    foreach (HtmlElement item in ElementCollection)         //    {         //         File.AppendAllText("Kaijiang_xj.txt", item.InnerText);         //    }         //}                //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 = tr.GetElementsByTagName("TD")[1].InnerText;                string strSinger = tr.GetElementsByTagName("TD")[1].InnerText;                //插入DataTable                strID = strID.Replace(".", "");                //AddLine(strID, strName, strSinger, "0");                //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");                ////插入DataTable                //strID = strID.Replace(".", "");                //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;        }        private void button2_Click(object sender, EventArgs e)        {            try {                WebClient MyWebClient = new WebClient();                MyWebClient.Credentials = CredentialCache.DefaultCredentials;//获取或设置用于向Internet资源的请求进行身份验证的网络凭据                Byte[] pageData = MyWebClient.DownloadData("http://bbs.cup.edu.cn/cupbbs/ThreadList.aspx?fid=51"); //从指定网站下载数据                //string pageHtml = Encoding.Default.GetString(pageData);  //如果获取网站页面采用的是GB2312，则使用这句                            string pageHtml = Encoding.UTF8.GetString(pageData); //如果获取网站页面采用的是UTF-8，则使用这句                Console.WriteLine(pageHtml);//在控制台输入获取的内容                using (StreamWriter sw = new StreamWriter("C:\\Users\\yuan\\Desktop\\ouput.html"))//将获取的内容写入文本                {                    sw.Write(pageHtml);                }                Console.ReadLine(); //让控制台暂停,否则一闪而过了                         }            catch(WebException webEx) {                Console.WriteLine(webEx.Message.ToString());            }        }        void web_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)        {            WebBrowser web = (WebBrowser)sender;            HtmlElementCollection ElementCollection = web.Document.GetElementsByTagName("Table");            foreach (HtmlElement item in ElementCollection)            {                File.AppendAllText("C:\\Users\\yuan\\Desktop\\ouputbutton3.txt", item.InnerText);            }        }        private void button3_Click(object sender, EventArgs e)        {            WebBrowser web = new WebBrowser();            web.Navigate("http://www.chinahighway.gov.cn/html/staticHtml/front/index_lkcx.html");             web.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(web_DocumentCompleted);         }        private void button4_Click(object sender, EventArgs e)        {            string _StrResponse = "";            HttpWebRequest _WebRequest = (HttpWebRequest)WebRequest.Create("http://bbs.cup.edu.cn/cupbbs/ThreadList.aspx?fid=51");            _WebRequest.UserAgent = "MOZILLA/4.0 (COMPATIBLE; MSIE 7.0; WINDOWS NT 5.2; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)";            _WebRequest.Method = "Get";            WebResponse _WebResponse = _WebRequest.GetResponse();            StreamReader _ResponseStream = new StreamReader(_WebResponse.GetResponseStream(), System.Text.Encoding.GetEncoding("gb2312"));            _StrResponse = _ResponseStream.ReadToEnd();            _WebResponse.Close();            _ResponseStream.Close();            File.AppendAllText("C:\\Users\\yuan\\Desktop\\ouputbutton4.txt", _StrResponse);        }        private void button5_Click(object sender, EventArgs e)        {            System.Net.WebClient WebClientObj = new System.Net.WebClient();            System.Collections.Specialized.NameValueCollection PostVars = new System.Collections.Specialized.NameValueCollection();            PostVars.Add("__VIEWSTATE", "dDwxNDMyMjQ3NTY4O3Q8O2w8aTwxPjs+O2w8dDw7bDxpPDM+O2k8Nz47PjtsPHQ8O2w8aTwwPjtpPDE+O2k8Mj47aTwzPjtpP........省略了，太长了.......");            //PostVars.Add("__EVENTVALIDATION", "此处是您需要提前得到的信息");            PostVars.Add("__EVENTTARGET", "grdThreadList:_ctl27:_ctl3");            //PostVars.Add("__EVENTARGUMENT", "");            //string s = "23$74$56";            //string[] str=new string[5];            //str=s.Split('$');            WebClientObj.Headers.Add("ContentType", "application/x-www-form-urlencoded");            try            {                byte[] byte1 = WebClientObj.UploadValues("http://bbs.cup.edu.cn/cupbbs/ThreadList.aspx?fid=51", "POST", PostVars);                string ResponseStr = Encoding.UTF8.GetString(byte1); //得到当前页面对应的html 文本字符串                //GetPostValue(ResponseStr);//得到当前页面对应的 __VIEWSTATE 等上面需要的信息，为抓取下一页面使用                //SaveMessage(ResponseStr);//保存自己关心的内容到数据库中                File.AppendAllText("C:\\Users\\yuan\\Desktop\\ouputbutton5.txt", ResponseStr);            }            catch (Exception ex)            {                Console.WriteLine(ex.Message);            }        }        private static string current__viewstate="";//保存当前页面对应的 __VIEWSTATE 等上面需要的信息，为再次点击按钮（抓取下一页面）使用        private string GetPostValue(string ResponseStr)        {            //......            return "";//略//解析ResponseStr，得到__VIEWSTATE的值        }        private void button6_Click(object sender, EventArgs e)        {            System.Net.WebClient WebClientObj = new System.Net.WebClient();            System.Collections.Specialized.NameValueCollection PostVars = new System.Collections.Specialized.NameValueCollection();            PostVars.Add("__VIEWSTATE", current__viewstate);            ////PostVars.Add("__EVENTVALIDATION", "此处是您需要提前得到的信息");            PostVars.Add("__EVENTTARGET", "grdThreadList:_ctl27:_ctl3");//通过for,改变其值，ctl1,ctl2,ctl3....            ////PostVars.Add("__EVENTARGUMENT", "");            ////string s = "23$74$56";            ////string[] str=new string[5];            ////str=s.Split('$');            WebClientObj.Headers.Add("ContentType", "application/x-www-form-urlencoded");            try            {                byte[] byte1 = WebClientObj.UploadValues("http://www.chinahighway.gov.cn/html/staticHtml/front/index_lkcx.html", "POST", PostVars);                string ResponseStr = Encoding.UTF8.GetString(byte1); //得到当前页面对应的html 文本字符串                current__viewstate=GetPostValue(ResponseStr);//得到当前页面对应的 __VIEWSTATE 等上面需要的信息，为抓取下一页面使用                //SaveMessage(ResponseStr);//保存自己关心的内容到数据库中                File.AppendAllText("C:\\Users\\yuan\\Desktop\\ouputbutton6.txt", ResponseStr);            }            catch (Exception ex)            {                Console.WriteLine(ex.Message);            }        }        private void button7_Click(object sender, EventArgs e)        {            try            {                WebClient MyWebClient = new WebClient();                MyWebClient.Credentials = CredentialCache.DefaultCredentials;//获取或设置用于向Internet资源的请求进行身份验证的网络凭据                Byte[] pageData = MyWebClient.DownloadData("http://gb.cri.cn/42071/2013/03/05/3245s4038640_2.htm"); //从指定网站下载数据                string pageHtml = Encoding.Default.GetString(pageData);  //如果获取网站页面采用的是GB2312，则使用这句                            //string pageHtml = Encoding.UTF8.GetString(pageData); //如果获取网站页面采用的是UTF-8，则使用这句                Console.WriteLine(pageHtml);//在控制台输入获取的内容                using (StreamWriter sw = new StreamWriter("C:\\Users\\yuan\\Desktop\\ouput7.html"))//将获取的内容写入文本                {                    sw.Write(pageHtml);                }                Console.ReadLine(); //让控制台暂停,否则一闪而过了                         }            catch (WebException webEx)            {                Console.WriteLine(webEx.Message.ToString());            }        }        //对分页数据抓取，当网页上【下一页】的属性是.gif格式的时候，而且鼠标停在【下一页】上面，页面下面显示的网址不完整（网址太长，只能看到部分），        //可以通过在网页上点击右键【查看源文件】,或F12【脚本】，找到对应的href，即可得到网址。        private void button8_Click(object sender, EventArgs e)        {            try            {                WebClient MyWebClient = new WebClient();                MyWebClient.Credentials = CredentialCache.DefaultCredentials;//获取或设置用于向Internet资源的请求进行身份验证的网络凭据                Byte[] pageData = MyWebClient.DownloadData("http://www.chinahighway.gov.cn/roadInfo/queryRoadInfo.do?queryType=map&startDate=&cantonName=&cantonCode=&infoType=3&endDate=&startPlanDate=&_page_size=50&roadName=&mapList=-1&endRealDate=&roadCode=&provinceList=-1&endPlanDate=&startRealDate=&page=3"); //从指定网站下载数据                string pageHtml = Encoding.Default.GetString(pageData);  //如果获取网站页面采用的是GB2312，则使用这句                            //string pageHtml = Encoding.UTF8.GetString(pageData); //如果获取网站页面采用的是UTF-8，则使用这句                Console.WriteLine(pageHtml);//在控制台输入获取的内容                using (StreamWriter sw = new StreamWriter("C:\\Users\\yuan\\Desktop\\ouput8.txt"))//将获取的内容写入文本                {                    sw.Write(pageHtml);                }                Console.ReadLine(); //让控制台暂停,否则一闪而过了                         }            catch (WebException webEx)            {                Console.WriteLine(webEx.Message.ToString());            }        }    }}