C#解析HTML

第一种方法：用正则表达式来分析

转自网上的一个实例：所有的href都抽取出来：using System;using System.Net;using System.Text;using System.Text.RegularExpressions;namespace HttpGet{    class Class1    {        [STAThread]        static void Main(string[] args)        {            System.Net.WebClient client = new WebClient();            byte[] page = client.DownloadData("http://www.google.com");            string content = System.Text.Encoding.UTF8.GetString(page);            string regex = "href=[\\\"\\\'](http:\\/\\/|\\.\\/|\\/)?\\w+(\\.\\w+)*(\\/\\w+(\\.\\w+)?)*(\\/|\\?\\w*=\\w*(&\\w*=\\w*)*)?[\\\"\\\']";            Regex re = new Regex(regex);            MatchCollection matches = re.Matches(content);            System.Collections.IEnumerator enu = matches.GetEnumerator();            while (enu.MoveNext() && enu.Current != null)            {                Match match = (Match)(enu.Current);                Console.Write(match.Value + "\r\n");            }        }    }}一些爬虫的HTML解析中也是用的类似的方法。

第二中方法：利用Winista.Htmlparser.Net 解析Html

1.  下载：

http://www.netomatix.com/Products/DocumentManagement/HTMLParserNet.aspx

2. 使用实例1

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 Winista.Text.HtmlParser;using Winista.Text.HtmlParser.Lex;using Winista.Text.HtmlParser.Util;using Winista.Text.HtmlParser.Tags;using Winista.Text.HtmlParser.Filters;namespace HTMLParser{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();            AddUrl();        }        private void btnParser_Click(object sender, EventArgs e)        {            #region 获得网页的html            try            {                txtHtmlWhole.Text = "";                string url = CBUrl.SelectedItem.ToString().Trim();                System.Net.WebClient aWebClient = new System.Net.WebClient();                aWebClient.Encoding = System.Text.Encoding.Default;                string html = aWebClient.DownloadString(url);                txtHtmlWhole.Text = html;            }            catch (Exception ex)            {                MessageBox.Show(ex.Message);            }            #endregion            #region 分析网页html节点            Lexer lexer = new Lexer(this.txtHtmlWhole.Text);            Parser parser = new Parser(lexer);            NodeList htmlNodes = parser.Parse(null);            this.treeView1.Nodes.Clear();            this.treeView1.Nodes.Add("root");            TreeNode treeRoot = this.treeView1.Nodes[0];            for (int i = 0; i < htmlNodes.Count; i++)            {                this.RecursionHtmlNode(treeRoot, htmlNodes[i], false);            }            #endregion        }        private void RecursionHtmlNode(TreeNode treeNode, INode htmlNode, bool siblingRequired)        {            if (htmlNode == null || treeNode == null) return;            TreeNode current = treeNode;            TreeNode content ;            //current node            if (htmlNode is ITag)            {                ITag tag = (htmlNode as ITag);                if (!tag.IsEndTag())                {                    string nodeString = tag.TagName;                    if (tag.Attributes != null && tag.Attributes.Count > 0)                    {                        if (tag.Attributes["ID"] != null)                        {                            nodeString = nodeString + " { id=\"" + tag.Attributes["ID"].ToString() + "\" }";                        }                        if (tag.Attributes["HREF"] != null)                        {                            nodeString = nodeString + " { href=\"" + tag.Attributes["HREF"].ToString() + "\" }";                        }                    }                                        current = new TreeNode(nodeString);                    treeNode.Nodes.Add(current);                }            }            //获取节点间的内容            if (htmlNode.Children != null && htmlNode.Children.Count > 0)            {                this.RecursionHtmlNode(current, htmlNode.FirstChild, true);                content = new TreeNode(htmlNode.FirstChild.GetText());                treeNode.Nodes.Add(content);            }            //the sibling nodes            if (siblingRequired)            {                INode sibling = htmlNode.NextSibling;                while (sibling != null)                {                    this.RecursionHtmlNode(treeNode, sibling, false);                    sibling = sibling.NextSibling;                }            }        }        private void AddUrl()        {            CBUrl.Items.Add("http://www.hao123.com");            CBUrl.Items.Add("http://www.sina.com");            CBUrl.Items.Add("http://www.heuet.edu.cn");        }            }}

运行效果：
实现取来很容易，结合Winista.Htmlparser源码很快就可以实现想要的效果。

3. 使用实例2

using Winista.Text.HtmlParser;using Winista.Text.HtmlParser.Tags;using Winista.Text.HtmlParser.Filters;using Winista.Text.HtmlParser.Util;            string str = "<table><tr><td>姓名</td><td>林肯</td></tr><tr><td>年龄</td><td>28</td></tr><tr><td>性别</td><td>男</td></tr><tr><td>姓名</td><td>克林顿</td></tr><tr><td>年龄</td><td>38</td></tr><tr><td>性别</td><td>男</td></tr></table>";            Parser parser = Parser.CreateParser( str , null );            NodeList nodes = parser.ExtractAllNodesThatMatch( new TagNameFilter("td") );            this.Page.Response.Write("<b>原来的html:</b>" + str  );            this.Page.Response.Write("<b>转换后的html:</b><br>" );            for( int i = 5 ; i >= 0 ; i-- )            {                this.Page.Response.Write( nodes[i*2].FirstChild.ToHtml() + nodes[i*2+1].FirstChild.GetText() + "<br>" );            }

运行结果如下：

原来的html:

姓名林肯年龄28性别男姓名克林顿年龄38性别男转换后的html:

性别男

年龄38

姓名克林顿

性别男

年龄28

姓名林肯

0

0

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