DropDownList 控件

呈现状态

<select name=”DropDownList”id=“DropDownList”>

         <option value=“A”>111</option>

         <option value=“B”>222</option>

         <option value=“C”>333</option>

         <option value=“D”>444</option>

</select>

控件语法

<asp:DropDownList ID=”DropDownList1”runat=”server”>
        <asp:ListItem Value=”A”>111</asp:ListItem>
        <asp:ListItem Value=”B”>222</asp:ListItem>
        <asp:ListItem Value=”C”>333</asp:ListItem>
        <asp:ListItem Value=”D”>444</asp:ListItem>
  </asp:DropDownList>

它有三种主要的属性

     Text 显示的值

     Value 隐藏的值

     selectIndex 下标 从0开始

 

.NET

     <asp:DropDownList ID="DropDownList2" runat="server">
            <asp:ListItem Value="http://www.baidu.com">百度</asp:ListItem>
            <asp:ListItem Value="http://www.51cto.com">51cto</asp:ListItem>
        </asp:DropDownList>
　　　　　　　　//按钮控件和事件
            <asp:Button ID="Button1" runat="server" Text="GO" OnClick="Button1_Click" />
            <asp:Button ID="Button2" runat="server" Text="change" OnClick="Button2_Click" />
<asp:Button ID="Button3" runat="server" Text="Add" OnClick="Button3_Click" />



C#

  
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        TextBox1.Text = DropDownList1.SelectedValue;
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        Response.Redirect(DropDownList2.SelectedValue);  //response 以HTTP的方式打开  redirect 将请求重定向URL
    }
    protected void Button2_Click(object sender, EventArgs e)
    {
        DropDownList2.Items[0].Text = "QQ";
        DropDownList2.Items[0].Value = "http://www.qq.com";
    }
    protected void Button3_Click(object sender, EventArgs e)
    {
        ListItem objli = new ListItem();
        objli.Text = "京东";
        objli.Value = "http://www.jd.com";

        DropDownList2.Items.Add(objli);
    }