C#正则表达式抓取网站信息

我就是我 2021-09-10 05:54 199阅读 0赞

C\#正则表达式抓取它网信息，本示例以抓取京东商城商品详情为例。

**1、创建JdRobber.cs程序类**

public class JdRobber
    {
        /// <summary>
        /// 判断是否京东链接
        /// </summary>
        /// <param name="param"></param>
        /// <returns></returns>
        public bool ValidationUrl(string url)
        {
            bool result = false;
            if (!String.IsNullOrEmpty(url))
            {
                Regex regex = new Regex(@"^http://item.jd.com/\d+.html$");
                Match match = regex.Match(url);
                if (match.Success)
                {
                    result = true;
                }
            }
            return result;
        }
    
        /// <summary>
        /// 抓取京东信息
        /// </summary>
        /// <param name="param"></param>
        /// <returns></returns>
        public void GetInfo(string url)
        {
            if (ValidationUrl(url))
            {
                string htmlStr = WebHandler.GetHtmlStr(url, "Default");
                if (!String.IsNullOrEmpty(htmlStr))
                {
                    string pattern = "";          //正则表达式
                    string sourceWebID = "";      //商品关键ID
                    string title = "";            //标题
                    decimal price = 0;            //价格
                    string picName = "";          //图片
    
                    //提取商品关键ID
                    pattern = @"http://item.jd.com/(?<Object>\d+).html";
                    sourceWebID = WebHandler.GetRegexText(url, pattern);
    
                    //提取标题
                    pattern = @"<div.*id=\""name\"".*>[\s\S]*<h1>(?<Object>.*?)</h1>";
                    title = WebHandler.GetRegexText(htmlStr, pattern);
    
                    //提取图片
                    int begin = htmlStr.IndexOf("<div id=\"spec-n1\"");
                    int end = htmlStr.IndexOf("</div>", begin + 1);
                    if (begin > 0 && end > 0)
                    {
                        string subPicHtml = htmlStr.Substring(begin, end - begin);
                        pattern = @"<img.*src=\""(?<Object>.*?)\"".*/>";
                        picName = WebHandler.GetRegexText(subPicHtml, pattern);
                    }
    
                    //提取价格
                    if (sourceWebID != "")
                    {
                        string priceUrl = @"http://p.3.cn/prices/get?skuid=J_" + sourceWebID + "&type=1";
                        string priceJson = WebHandler.GetHtmlStr(priceUrl, "Default");
                        pattern = @"\""p\"":\""(?<Object>\d+(\.\d{1,2})?)\""";
                        price = WebHandler.GetValidPrice(WebHandler.GetRegexText(priceJson, pattern));
                    }
    
                    Console.WriteLine("商品名称：{0}", title);
                    Console.WriteLine("图片：{0}", picName);
                    Console.WriteLine("价格：{0}", price);
                }
            }
        }
    }

**2、创建WebHandler.cs公共方法类**

/// <summary>
    /// 公共方法类
    /// </summary>
    public class WebHandler
    {
        /// <summary>
        /// 获取网页的HTML码
        /// </summary>
        /// <param name="url">链接地址</param>
        /// <param name="encoding">编码类型</param>
        /// <returns></returns>
        public static string GetHtmlStr(string url, string encoding)
        {
            string htmlStr = "";
            try
            {
                if (!String.IsNullOrEmpty(url))
                {
                    WebRequest request = WebRequest.Create(url);            //实例化WebRequest对象
                    WebResponse response = request.GetResponse();           //创建WebResponse对象
                    Stream datastream = response.GetResponseStream();       //创建流对象
                    Encoding ec = Encoding.Default;
                    if (encoding == "UTF8")
                    {
                        ec = Encoding.UTF8;
                    }
                    else if (encoding == "Default")
                    {
                        ec = Encoding.Default;
                    }
                    StreamReader reader = new StreamReader(datastream, ec);
                    htmlStr = reader.ReadToEnd();                           //读取数据
                    reader.Close();
                    datastream.Close();
                    response.Close();
                }
            }
            catch { }
            return htmlStr;
        }
    
        /// <summary>
        /// 获取正则表达式中的关键字
        /// </summary>
        /// <param name="input">文本</param>
        /// <param name="pattern">表达式</param>
        /// <returns></returns>
        public static string GetRegexText(string input, string pattern)
        {
            string result = "";
            if (!String.IsNullOrEmpty(input) && !String.IsNullOrEmpty(pattern))
            {
                Regex regex = new Regex(pattern, RegexOptions.IgnoreCase);
                Match match = regex.Match(input);
                if (match.Success)
                {
                    result = match.Groups["Object"].Value;
                }
            }
            return result;
        }
    
        /// <summary>
        /// 返回有效价格
        /// </summary>
        /// <param name="strPrice"></param>
        /// <returns></returns>
        public static decimal GetValidPrice(string strPrice)
        {
            decimal price = 0;
            try
            {
                if (!String.IsNullOrEmpty(strPrice))
                {
                    Regex regex = new Regex(@"^\d+(\.\d{1,2})?$", RegexOptions.IgnoreCase);
                    Match match = regex.Match(strPrice);
                    if (match.Success)
                    {
                        price = decimal.Parse(strPrice);
                    }
                }
            }
            catch { }
            return price;
        }
    }