C#网络爬虫

由于公司的编辑需要！做了一个小玩意！

这是爬取网页内容，像是这对大家来说都是不难得，但是在这里有一些小改动，代码献上，大家参考

 private string GetHttpWebRequest(string url)        {            HttpWebResponse result;            string strHTML = string.Empty;            try            {                Uri uri = new Uri(url);                WebRequest webReq = WebRequest.Create(uri);                WebResponse webRes = webReq.GetResponse();                HttpWebRequest myReq = (HttpWebRequest)webReq;                myReq.UserAgent = "User-Agent:Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705";                myReq.Accept = "*/*";                myReq.KeepAlive = true;                myReq.Headers.Add("Accept-Language", "zh-cn,en-us;q=0.5");                result = (HttpWebResponse)myReq.GetResponse();                Stream receviceStream = result.GetResponseStream();                StreamReader readerOfStream = new StreamReader(receviceStream, System.Text.Encoding.GetEncoding("utf-8"));                strHTML = readerOfStream.ReadToEnd();                readerOfStream.Close();                receviceStream.Close();                result.Close();            }            catch            {                Uri uri = new Uri(url);                WebRequest webReq = WebRequest.Create(uri);                HttpWebRequest myReq = (HttpWebRequest)webReq;                myReq.UserAgent = "User-Agent:Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705";                myReq.Accept = "*/*";                myReq.KeepAlive = true;                myReq.Headers.Add("Accept-Language", "zh-cn,en-us;q=0.5");                //result = (HttpWebResponse)myReq.GetResponse();                try                {                    result = (HttpWebResponse)myReq.GetResponse();                }                catch (WebException ex)                {                    result = (HttpWebResponse)ex.Response;                }                Stream receviceStream = result.GetResponseStream();                StreamReader readerOfStream = new StreamReader(receviceStream, System.Text.Encoding.GetEncoding("gb2312"));                strHTML = readerOfStream.ReadToEnd();                readerOfStream.Close();                receviceStream.Close();                result.Close();            }            return strHTML;        }

这是根据url爬取网页远吗，有以下小改动，很多网页有不同的编码格式，甚至有些网站做了反爬取的防范

这是爬取网页所有的网址链接

方法如下：

/// <summary>        /// 提取HTML代码中的网址        /// </summary>        /// <param name="htmlCode"></param>        /// <returns></returns>        private static List<string> GetHyperLinks(string htmlCode, string url)        {            ArrayList al = new ArrayList();            bool IsGenxin = false;            StringBuilder weburlSB = new StringBuilder();//SQL            StringBuilder linkSb = new StringBuilder();//展示数据            List<string> Weburllistzx = new List<string>();//新增            List<string> Weburllist = new List<string>();//旧的            string ProductionContent = htmlCode;            Regex reg = new Regex(@"http(s)?://([\w-]+\.)+[\w-]+/?");            string wangzhanyuming = reg.Match(url, 0).Value;            MatchCollection mc = Regex.Matches(ProductionContent.Replace("href=\"/", "href=\"" + wangzhanyuming).Replace("href='/", "href='" + wangzhanyuming).Replace("href=/", "href=" + wangzhanyuming).Replace("href=\"./", "href=\"" + wangzhanyuming), @"<[aA][^>]* href=[^>]*>", RegexOptions.Singleline);            int Index = 1;            foreach (Match m in mc)            {                MatchCollection mc1 = Regex.Matches(m.Value, @"[a-zA-z]+://[^\s]*", RegexOptions.Singleline);                if (mc1.Count > 0)                {                    foreach (Match m1 in mc1)                    {                        string linkurlstr = string.Empty;                        linkurlstr = m1.Value.Replace("\"", "").Replace("'", "").Replace(">", "").Replace(";", "");                        weburlSB.Append("$-$");                        weburlSB.Append(linkurlstr);                        weburlSB.Append("$_$");                        if (!Weburllist.Contains(linkurlstr) && !Weburllistzx.Contains(linkurlstr))                        {                            IsGenxin = true;                            Weburllistzx.Add(linkurlstr);                            linkSb.AppendFormat("{0}<br/>", linkurlstr);                        }                    }                }                else                {                    if (m.Value.IndexOf("javascript") == -1)                    {                        string amstr = string.Empty;                        string wangzhanxiangduilujin = string.Empty;                        wangzhanxiangduilujin = url.Substring(0, url.LastIndexOf("/") + 1);                        amstr = m.Value.Replace("href=\"", "href=\"" + wangzhanxiangduilujin).Replace("href='", "href='" + wangzhanxiangduilujin);                        MatchCollection mc11 = Regex.Matches(amstr, @"[a-zA-z]+://[^\s]*", RegexOptions.Singleline);                        foreach (Match m1 in mc11)                        {                            string linkurlstr = string.Empty;                            linkurlstr = m1.Value.Replace("\"", "").Replace("'", "").Replace(">", "").Replace(";", "");                            weburlSB.Append("$-$");                            weburlSB.Append(linkurlstr);                            weburlSB.Append("$_$");                            if (!Weburllist.Contains(linkurlstr) && !Weburllistzx.Contains(linkurlstr))                            {                                IsGenxin = true;                                Weburllistzx.Add(linkurlstr);                                linkSb.AppendFormat("{0}<br/>", linkurlstr);                            }                        }                    }                }                Index++;            }            return Weburllistzx;        }

这块的技术其实就是简单的使用了正则去匹配！

/// <summary>        /// // 把网址写入xml文件        /// </summary>        /// <param name="strURL"></param>        /// <param name="alHyperLinks"></param>        private static void WriteToXml(string strURL, List<string> alHyperLinks)        {            XmlTextWriter writer = new XmlTextWriter(@"D:\HyperLinks.xml", Encoding.UTF8);            writer.Formatting = Formatting.Indented;            writer.WriteStartDocument(false);            writer.WriteDocType("HyperLinks", null, "urls.dtd", null);            writer.WriteComment("提取自" + strURL + "的超链接");            writer.WriteStartElement("HyperLinks");            writer.WriteStartElement("HyperLinks", null);            writer.WriteAttributeString("DateTime", DateTime.Now.ToString());            foreach (string str in alHyperLinks)            {                string title = GetDomain(str);                string body = str;                writer.WriteElementString(title, null, body);            }            writer.WriteEndElement();            writer.WriteEndElement();            writer.Flush();            writer.Close();        }        /// <summary>        /// 获取网址的域名后缀        /// </summary>        /// <param name="strURL"></param>        /// <returns></returns>        private static string GetDomain(string strURL)        {            string retVal;            string strRegex = @"(\.com/|\.net/|\.cn/|\.org/|\.gov/)";            Regex r = new Regex(strRegex, RegexOptions.IgnoreCase);            Match m = r.Match(strURL);            retVal = m.ToString();            strRegex = @"\.|/$";            retVal = Regex.Replace(retVal, strRegex, "").ToString();            if (retVal == "")                retVal = "other";            return retVal;        }/// <summary>        /// 获取标题        /// </summary>        /// <param name="html"></param>        /// <returns></returns>        private static string GetTitle(string html)        {            string titleFilter = @"<title>[\s\S]*?</title>";            string h1Filter = @"<h1.*?>.*?</h1>";            string clearFilter = @"<.*?>";            string title = "";            Match match = Regex.Match(html, titleFilter, RegexOptions.IgnoreCase);            if (match.Success)            {                title = Regex.Replace(match.Groups[0].Value, clearFilter, "");            }            // 正文的标题一般在h1中，比title中的标题更干净            match = Regex.Match(html, h1Filter, RegexOptions.IgnoreCase);            if (match.Success)            {                string h1 = Regex.Replace(match.Groups[0].Value, clearFilter, "");                if (!String.IsNullOrEmpty(h1) && title.StartsWith(h1))                {                    title = h1;                }            }            return title;        }

这就是所用的全部方法，还是有很多需要改进之处！大家如果有发现不足之处还请指出，谢谢！