C#快速获取指定网页源码的几种方式，并通过字符串截取函数 或 正则 取指定内容(IP)

//只获取网页源码开始到标题位目的进行测试

//第一种方式经过测试，稍微快点

 string url = "http://www.ip.cn";

            HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);

            req.Method = "GET";

            req.ContentType = "application/x-www-form-urlencoded";

            HttpWebResponse res = (HttpWebResponse)req.GetResponse();

            Stream ReceiveStream = res.GetResponseStream();

            Encoding encode = System.Text.Encoding.UTF8;

            StreamReader sr = new StreamReader(ReceiveStream, encode);

            string strResult = "";

            Char[] read = new Char[];

            int count = sr.Read(read, , );

            while (count > )

            {

                String str = new String(read, , count);

                strResult += str;

                count = sr.Read(read, , );

                if (strResult.IndexOf("</title>") != -)

                {

                    break;

                }

            }

            textBoxTest.Text = strResult;

//第二种获取网页源码

WebClient MyClient = new WebClient();

MyClient.Credentials = CredentialCache.DefaultCredentials;

MyClient.Headers.Add("Host", "www.kuwo.cn");

MyClient.Headers.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36");

Byte[] pageData = MyClient.DownloadData(url);

//string pageHtml = Encoding.Default.GetString(pageData);  //GB2312

string pageHtml = Encoding.UTF8.GetString(pageData); //UTF-8

//字符串截取，从网页源码中截取 两字符串中间信息

private string GetStr(string TxtStr, string FirstStr, string SecondStr)

        {

            if (FirstStr.IndexOf(SecondStr, ) != -)

                return "";

            int FirstSite = TxtStr.IndexOf(FirstStr, );

            int SecondSite = TxtStr.IndexOf(SecondStr, FirstSite + );

            if (FirstSite == - || SecondSite == -)

                return "";

            return TxtStr.Substring(FirstSite + FirstStr.Length, SecondSite - FirstSite - FirstStr.Length);

        }

//正则截取字符串 A.B之间

string title2 = Regex.Match(title, "(?<="+"A"+").*?(?="+"B"+")").Value;

//Regex.Match(sUrl, "(?<=A).*?(?=B)").Value;

 //自定义函数

private string MyGetTitle(string url, string endTag, string startStr, string endStr)

        {

            try

            {

                //HttpWebRequest类继承于WebRequest，并没有自己的构造函数，需通过WebRequest的Creat方法 建立，并进行强制的类型转换

                HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);

                req.Method = "GET";

                req.ContentType = "text/html;charset=UTF-8";

                //通过HttpWebRequest的GetResponse()方法建立HttpWebResponse,强制类型转换

                HttpWebResponse res = (HttpWebResponse)req.GetResponse();

                //若成功取得网页的内容，则以System.IO.Stream形式返回，

                //若失败则产生ProtoclViolationException错 误。

                //在此正确的做法应将以下的代码放到一个try块中处理。这里简单处理

                Stream ReceiveStream = res.GetResponseStream();

                //返回的内容是Stream形式的，所以可以利用StreamReader类获取GetResponseStream的内容,

                //并以StreamReader类的Read方法依次读取网页源程序代码每一行的内容，直至行尾（读取的编码格式：UTF8）

                StreamReader sr = new StreamReader(ReceiveStream, Encoding.UTF8);

                string strResult = "";

                Char[] read = new Char[];

                //Read(char[] buffer,int index,int count);

                //从文件流的第index个位置开始读，到count个字符，把它们存到buffer中，

                //然后返回一个正数，内部指针后移一位，保证下次从新的位置开始读。

                int count = sr.Read(read, , );

                while (count > )

                {

                    String str = new String(read, , count);

                    strResult += str;

                    count = sr.Read(read, , );

                    if (strResult.IndexOf(endTag) != -) break;

                }

                res.Close();

                ReceiveStream.Dispose();

                return Regex.Match(strResult, "(?<=" + startStr + ").*?(?=" + endStr + ")").Value;

            }

            catch (Exception ex)

            {

                LogAdd(ListBoxDownLog, "异常：" + ex.Message);

                throw;

            }

        }