class h
{
    public static string getPro(HtmlNode node, string proname)
    {
        return node.GetAttributeValue(proname, "");
    }

    public static HtmlNodeCollection Parse(string htm,string xpath)
    {
        var doc = new HtmlDocument();
        doc.LoadHtml(htm);
        return doc.DocumentNode.SelectNodes(xpath);
    }


    public static HtmlNode[] Contains(HtmlNodeCollection collection,string key,string value)
    {
        var list = new List<HtmlNode>();
        foreach (var node in collection)
        {

            var pro = node.GetAttributeValue(key, "");
            if (!pro.Contains(value)) continue;
            list.Add(node);
        }
        return list.ToArray();
    }
    public static HtmlNode[] Equals(HtmlNodeCollection collection, string key, string value)
    {
        var list = new List<HtmlNode>();
        foreach (var node in collection)
        {
            var pro = node.GetAttributeValue(key, "");
            if (pro !=value) continue;

            list.Add(node);
        }
        return list.ToArray();
    }

}

public class u

{
    public static MatchCollection getMidValue(string begin, string end, string html)
    {
        Regex reg = new Regex("(?<=(" + begin + "))[.\\s\\S]*?(?=(" + end + "))", RegexOptions.Multiline | RegexOptions.Singleline);
        return reg.Matches(html);
    }
    static public string getvalue(string str, string start, string end)
    {
        Regex rg = new Regex("(?<=(" + start + "))[.\\s\\S]*?(?=(" + end + "))", RegexOptions.Multiline | RegexOptions.Singleline);

        return rg.Match(str).Value;
    }
    static public string noHtml(string Htmlstring) //去除HTML标记
    {
        //删除脚本
        Htmlstring = Regex.Replace(Htmlstring, @"<script[^>]*?>.*?</script>", "", RegexOptions.IgnoreCase);
        //删除HTML
        Htmlstring = Regex.Replace(Htmlstring, @"<(.[^>]*)>", "", RegexOptions.IgnoreCase);
        Htmlstring = Regex.Replace(Htmlstring, @"([\r
])[\s]+", "", RegexOptions.IgnoreCase);
        Htmlstring = Regex.Replace(Htmlstring, @"-->", "", RegexOptions.IgnoreCase);
        Htmlstring = Regex.Replace(Htmlstring, @"<!--.*", "", RegexOptions.IgnoreCase);

        Htmlstring = Regex.Replace(Htmlstring, @"&(quot|#34);", "\"", RegexOptions.IgnoreCase);
        Htmlstring = Regex.Replace(Htmlstring, @"&(amp|#38);", "&", RegexOptions.IgnoreCase);
        Htmlstring = Regex.Replace(Htmlstring, @"&(lt|#60);", "<", RegexOptions.IgnoreCase);
        Htmlstring = Regex.Replace(Htmlstring, @"&(gt|#62);", ">", RegexOptions.IgnoreCase);
        Htmlstring = Regex.Replace(Htmlstring, @"&(nbsp|#160);", " ", RegexOptions.IgnoreCase);
        Htmlstring = Regex.Replace(Htmlstring, @"&(iexcl|#161);", "\xa1", RegexOptions.IgnoreCase);
        Htmlstring = Regex.Replace(Htmlstring, @"&(cent|#162);", "\xa2", RegexOptions.IgnoreCase);
        Htmlstring = Regex.Replace(Htmlstring, @"&(pound|#163);", "\xa3", RegexOptions.IgnoreCase);
        Htmlstring = Regex.Replace(Htmlstring, @"&(copy|#169);", "\xa9", RegexOptions.IgnoreCase);
        Htmlstring = Regex.Replace(Htmlstring, @"&#(\d+);", "", RegexOptions.IgnoreCase);

        Htmlstring.Replace("<", "");
        Htmlstring.Replace(">", "");
        Htmlstring.Replace("\r
", "");

        return Htmlstring;
    }
}

public class w

{
    public static string get(string urlString)
    {
        return getutf8(urlString);
    }
    public static string getutf8(string urlString)
    {
        return get(urlString, Encoding.UTF8);
    }
    public static string getgbk(string urlString)
    {
        return get(urlString, Encoding.GetEncoding("gbk"));
    }
    public static string getgb2312(string urlString)
    {
        return get(urlString, Encoding.GetEncoding("gb2312"));
    }
    public static string get(string urlString, Encoding encoding)
    {
        //定义局部变量
        HttpWebRequest httpWebRequest = null;
        HttpWebResponse httpWebRespones = null;
        Stream stream = null;
        string htmlString = string.Empty;

        //请求页面
        try
        {
            httpWebRequest = WebRequest.Create(urlString) as HttpWebRequest;
        }
            //处理异常
        catch (Exception ex)
        {
            throw new Exception("建立页面请求时发生错误！", ex);
        }
        httpWebRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 2.0.50727; Maxthon 2.0)";
        //获取服务器的返回信息
        try
        {
            httpWebRespones = (HttpWebResponse)httpWebRequest.GetResponse();
            stream = httpWebRespones.GetResponseStream();
        }
            //处理异常
        catch (Exception ex)
        {
            throw new Exception("接受服务器返回页面时发生错误！", ex);
        }
        StreamReader streamReader = new StreamReader(stream, encoding);
        //读取返回页面
        try
        {
            htmlString = streamReader.ReadToEnd();
        }
            //处理异常
        catch (Exception ex)
        {
            throw new Exception("读取页面数据时发生错误！", ex);
        }
        //释放资源返回结果
        streamReader.Close();
        stream.Close();
        return htmlString;
    }

    /// <summary>
    /// 提供通过POST方法获取页面的方法
    /// </summary>
    /// <param name="urlString">请求的URL</param>
    /// <param name="encoding">页面使用的编码</param>
    /// <param name="postDataString">POST数据</param>
    /// <returns>获取的页面</returns>
    public static string post(string urlString, Encoding encoding, string postDataString)
    {
        //定义局部变量
        CookieContainer cookieContainer = new CookieContainer();
        HttpWebRequest httpWebRequest = null;
        HttpWebResponse httpWebResponse = null;
        Stream inputStream = null;
        Stream outputStream = null;
        StreamReader streamReader = null;
        string htmlString = string.Empty;
        //转换POST数据
        byte[] postDataByte = encoding.GetBytes(postDataString);
        //建立页面请求
        try
        {
            httpWebRequest = WebRequest.Create(urlString) as HttpWebRequest;
        }
            //处理异常
        catch (Exception ex)
        {
            throw new Exception("建立页面请求时发生错误！", ex);
        }
        //指定请求处理方式
        httpWebRequest.Method = "POST";
        httpWebRequest.KeepAlive = false;
        httpWebRequest.ContentType = "application/x-www-form-urlencoded";
        httpWebRequest.CookieContainer = cookieContainer;
        httpWebRequest.ContentLength = postDataByte.Length;
        //向服务器传送数据
        try
        {
            inputStream = httpWebRequest.GetRequestStream();
            inputStream.Write(postDataByte, 0, postDataByte.Length);
        }
            //处理异常
        catch (Exception ex)
        {
            throw new Exception("发送POST数据时发生错误！", ex);
        }
        finally
        {
            inputStream.Close();
        }
        //接受服务器返回信息
        try
        {
            httpWebResponse = httpWebRequest.GetResponse() as HttpWebResponse;
            outputStream = httpWebResponse.GetResponseStream();
            streamReader = new StreamReader(outputStream, encoding);
            htmlString = streamReader.ReadToEnd();
        }
            //处理异常
        catch (Exception ex)
        {
            throw new Exception("接受服务器返回页面时发生错误！", ex);
        }
        finally
        {
            streamReader.Close();
        }
        foreach (Cookie cookie in httpWebResponse.Cookies)
        {
            cookieContainer.Add(cookie);
        }
        return htmlString;
    }
}

C# 网络操作类