用HtmlLink来改变网站的主题

#region Theme

            // 注册样式(将主题样式至于通用样式后面)

            HtmlLink themeCss = new HtmlLink();

            themeCss.Href = GetThemeUrl();

            themeCss.Attributes["id"] = "commonPageStyle";

            themeCss.Attributes["rel"] = "stylesheet";

            themeCss.Attributes["type"] = "text/css";

            int commonCssIndex = 0;

            bool existsCommonCss = false;

            foreach (Control control in Page.Header.Controls)

            {

                if (control is HtmlLink && (control as HtmlLink).Href.IndexOf("/css/commPage.css", StringComparison.OrdinalIgnoreCase) > -1)

                {

                    Page.Header.Controls.AddAt(commonCssIndex + 1, themeCss);

                    existsCommonCss = true;

                    break;

                }

                commonCssIndex++;

            }

            if (!existsCommonCss)

            {

                Page.Header.Controls.AddAt(0, themeCss);

            }

            #endregion

private string GetThemeUrl()

        {

            string themeStr = "/css/themes/{0}/commPage.css?v=140917";

            switch (UserSession.getInstance().UserTheme)

            {

                case "blue":

                    themeStr = string.Format(themeStr, "blue");

                    break;

                case "purple":

                    themeStr = string.Format(themeStr, "purple");

                    break;

                case "red":

                    themeStr = string.Format(themeStr, "red");

                    break;

                case "green":

                    themeStr = string.Format(themeStr, "green");

                    break;

                default:

                    themeStr = string.Format(themeStr, "default");

                    break;

            }

            return themeStr;

        }