Asp.Net_后台代码访问前台html标签

//单击按钮后批量改变li元素的内联文本值及样式  
    for (int i = 1; i <= 8; i++)  
    {  
        HtmlGenericControl li = this.FindControl("li" + i) as HtmlGenericControl;  
        li.InnerHtml = "新值" + i.ToString();  
        li.Attributes.CssStyle.Value = "color:red";  
    }  

//单击按钮后批量改变li元素的内联文本值及样式  
    foreach (Control control in ul1.Controls)  
    {  
        if (control is HtmlGenericControl)  
        {  
            HtmlGenericControl li = control as HtmlGenericControl;  
            li.InnerHtml = "新值" + (counter++).ToString();  
            li.Attributes.CssStyle.Value = "color:red";  
        }  
    }  

//单击按钮后批量改变li元素的内联文本值及样式  
        HtmlDocument htmlDoc = new HtmlDocument();  
        htmlDoc.LoadHtml(ul1.InnerHtml);  
        HtmlNodeCollection lis = htmlDoc.DocumentNode.SelectNodes("li");  
        for (int i = 0; i < lis.Count; i++)  
        {  
            lis[i].InnerHtml = "新值" + (i + 1).ToString();  
            lis[i].Attributes.Add("style", "color:red");  
        }  
        ul1.InnerHtml = htmlDoc.DocumentNode.InnerHtml;