使用DropDownList控件和ListBox控件創建聊天室

using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

namespace 聊天室
{
    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            string strName = DropDownList1.SelectedItem.ToString(); //下拉控件目前選擇的內容
            switch (strName)
            {
                case "湖州聊天室":
                    ListBox1.Items.Clear();  //清空ListBox1控件中的內容
                    ListBox1.Items.Add("湖州安吉"); //添加內容
                    ListBox1.Items.Add("湖州長興");
                    ListBox1.Items.Add("湖州德清");
                    break;
                case "杭州聊天室":
                    ListBox1.Items.Clear();
                    ListBox1.Items.Add("杭州餘杭");
                    ListBox1.Items.Add("杭州臨安");
                    ListBox1.Items.Add("杭州建德");
                    break;
                case "寧波聊天室":
                    ListBox1.Items.Clear();
                    ListBox1.Items.Add("寧波餘姚");
                    ListBox1.Items.Add("寧波北侖");
                    ListBox1.Items.Add("寧波鄞州");
                    break;
                default:
                    break;
            }
        }
    }
}