WB列表框知识点

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    
        <asp:ListBox ID="ListBox1" runat="server" Height="187px" SelectionMode="Multiple" Width="141px"></asp:ListBox>
    
        <asp:LinqDataSource ID="LinqDataSource1" runat="server" ContextTypeName="TestDataContext" EntityTypeName="" TableName="Nation">
        </asp:LinqDataSource>
        <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" />
        <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
    
        <asp:Button ID="Button2" runat="server" OnClick="Button2_Click" Text="设置选中" />
    
    </div>
    </form>
</body>
</html>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            TestDataContext context = new TestDataContext();
            //用代码绑定数据
            ListBox1.DataSource = context.Nation;
            //显示哪一个字段
            ListBox1.DataTextField = "Name";
            ListBox1.DataValueField = "Code";
            //绑定
            ListBox1.DataBind();
        }
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        //取选中项的值  只适用于单选
        //Label1.Text = ListBox1.SelectedValue.ToString();
        //多选
        //清值
        Label1.Text = "";
        foreach (ListItem item in ListBox1.Items)
        {
            if (item.Selected)
            {
                Label1.Text += item.Value;//拼接字符串
            }
        }
       
    } 
    //设置哪像被选中
    protected void Button2_Click(object sender, EventArgs e)
    {
        foreach (ListItem item in ListBox1.Items)
        {
            if (item.Text=="汉族"|| item.Text=="满族")
            {
                item.Selected = true;
            }
        }
    }
}