下载网页通用类

    /// <summary>
    /// 根据网页地址去下载网页，包括从网页中获取自己所需要的内容
    /// </summary>
    public class WebWrapper
    {
        public WebWrapper() { }
        public WebWrapper(string link) { Link = link; }

        #region Download html

        public string Link { get; set; }
        public string DownLoadHtml(string link)
        {
            string htmlString = string.Empty;
            try
            {
                WebRequest webRequest = System.Net.WebRequest.Create(link);

                webRequest.Method = "GET";
                webRequest.ContentType = "application/x-www-form-urlencoded";
                using (StreamReader sr = new StreamReader(webRequest.GetResponse().GetResponseStream()))
                {
                    htmlString = sr.ReadToEnd();
                }
            }
            catch (Exception ex)
            {
                throw new ApplicationException(string.Format("Error Downloading CurrencyRate: {0}", ex.Message));
            }
            return htmlString;
        }
        public string DownLoadHtml()
        {
            if (string.IsNullOrEmpty(Link))
                throw new ApplicationException("Please input web address");
            return DownLoadHtml(Link);
        }

        #endregion

        #region Get matched content

        public string GetContent(string html, string regexExpress)
        {
            Regex re = new Regex(regexExpress);
            MatchCollection ms = re.Matches(html);
            if (ms == null || ms.Count == 0)
                throw new ApplicationException("Can not find matched content");

            return ms[0].ToString();
        }

        public string GetContent(string regexExpress)
        {
            string html = DownLoadHtml();
            return GetContent(html, regexExpress);
        }

        #endregion

        #region Regex Properties

        public string BeginConstruction = "(?<=({0}))";
        public string EndConstruction = "(?=({0}))";
        public string RegexBeginExpression(string begin) { return string.Format(BeginConstruction, begin); }
        public string RegexEndExpression(string end) { return string.Format(EndConstruction, end); }
        public string RegexAnyExpression { get { return "[.\s\S]*?"; } }

        #endregion
    }