<div>
        <% foreach (var studen in outhtml())
           {%>
        <p>学生姓名：<%=studen.StuName %></p>
        <p>学生学号：<%=studen.StuNumber %></p>
        <p>学生年龄：<%=studen.Age %></p>
        <%   }%>
    </div>
    <div runat="server" id="demo" style="height:50px;width:50px;"></div>

    <asp:Button ID="BtnChange" runat="server" Text="按钮"  OnClick="BtnChange_Click" />

public partial class Sheets_testalert : PortalPage
{
    protected void Page_Load(object sender, EventArgs e)
    {
    }
    public List<Student> outhtml()
    {
        List<Student> stulist = new List<Student>();
        Student Stu1 = new Student();
        Stu1.StuName = "小王";
        Stu1.StuNumber = "1123";
        Stu1.Age = 15;
        stulist.Add(Stu1);

        Student Stu2 = new Student();
        Stu2.StuName = "小王";
        Stu2.StuNumber = "1123";
        Stu2.Age = 15;
        stulist.Add(Stu2);
        return stulist;
    }
    protected void BtnChange_Click(object sender, EventArgs e)
    {
　　　　　//取得值判断，然后根据条件赋值
        if (this.demo.Style["background-color"] == "red")
        {
            this.demo.Style["background-color"] = "green"; 
        }
        else { 
            this.demo.Style["background-color"] = "red"; 
        }

    }
}
public class Student
{

    private string stuName;

    public string StuName
    {
        get { return stuName; }
        set { stuName = value; }
    }

    private string stuNumber;

    public string StuNumber
    {
        get { return stuNumber; }
        set { stuNumber = value; }
    }

    private int age;

    public int Age
    {
        get { return age; }
        set { age = value; }
    }

}