项目总结之数据抓取程序

需求，公司希望能够从自己的主页搜索其他公司主页查询数据，如此涉及到数据抓取功能。

实现原理，基于是WEB页面抓取，可以在内部代码中发送HTTP请求，返回HTML结果集。然后，在HTML结果集中解析本公司想要的数据信息。解析可以通过很多种方式，但是最常用的是正则表达式。

    public class GetHtmlByPost
    {
        public static string GetHtml(string DefaultIP, string DefaultUrl, string postData)
        {
            try
            {
                Encoding encoding = Encoding.GetEncoding("GB2312");
                string strUrl = @"http://" + DefaultIP + "" + DefaultUrl + "";
                //string postData = "Pfx=" + Pfx + "&Carrier=" + Carrier + "&Shipment=" + Shipment + "";
                byte[] data = encoding.GetBytes(postData);
                //   准备HTTP请求...  
                System.Net.HttpWebRequest myRequest = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(strUrl);
                myRequest.Method = "POST";
                myRequest.ContentType = "application/x-www-form-urlencoded";
                myRequest.ContentLength = data.Length;
                System.IO.Stream newStream = myRequest.GetRequestStream();
                //   发送数据  
                newStream.Write(data, 0, data.Length);
                newStream.Close();
                //HTTP响应  
                System.Net.HttpWebResponse myResponse = (System.Net.HttpWebResponse)myRequest.GetResponse();
                System.IO.Stream receiveStream = myResponse.GetResponseStream();
                Encoding encode = System.Text.Encoding.GetEncoding("GB2312");
                System.IO.StreamReader readStream = new System.IO.StreamReader(receiveStream, encode);
                Char[] read = new Char[256];
                int count = readStream.Read(read, 0, 256);
                StringBuilder sb = new StringBuilder("");
                while (count > 0)
                {
                    String readstr = new String(read, 0, count);
                    sb.Append(readstr);
                    count = readStream.Read(read, 0, 256);
                }

                myResponse.Close();
                readStream.Close();
                return sb.ToString();
            }
            catch { return ""; }
        }
    }
 

解析HTML代码经常会用到，获取<td></td>之间的数据，这里有一个通用表达式 @"(?is)(?<=>)[^<]+(?=<)"。

 //分组得到<td></td>数据
  MatchCollection strMatchCollection = Regex.Matches(“解析的字符串”, @"(?is)(?<=>)[^<]+(?=<)");
 //节点1 
 value1 = strMatchCollection[0].Value.ToString();
 //节点2 
 value1 = strMatchCollection[1].Value.ToString();
         

value1，value2即td节点数据值。