ListBox选项实现上下移动

aspx页面

 1<form id="form1" runat="server">
 2    <div>
 3    <asp:ListBox ID="ListBox1" runat="server">
 4        <asp:ListItem Text ="aaa"></asp:ListItem>
 5       <asp:ListItem Text ="bbb"></asp:ListItem> 
 6    </asp:ListBox>
 7   
 8   <asp:Button runat="server" ID = "Button1" OnClick="Button1_Click" Text="Up" /> 
 9   <asp:Button runat="server" ID = "Button2" OnClick="Button2_Click" Text="Down" /> 
    </div>
    </form>

cs页面

 1protected void Button1_Click(object sender, EventArgs e)
 2        {
 3            //up
 4            if (this.ListBox1.SelectedItem == null)
 5            {
 6                ClientScript.RegisterStartupScript(this.GetType(), "test", "<script>alert('Please select one item');</script>");
 7                return;
 8            }
 9
            int index = this.ListBox1.SelectedIndex;
            if (index != 0)
            {
                ListItem item = this.ListBox1.Items[index];
                this.ListBox1.Items.Remove(this.ListBox1.Items[index]);
                this.ListBox1.Items.Insert(index - 1, item);
            }
        }

        protected void Button2_Click(object sender, EventArgs e)
        {

            if (this.ListBox1.SelectedItem == null)
            {
                ClientScript.RegisterStartupScript(this.GetType(), "test", "<script>alert('Please select one item');</script>");
                return;
            }

            //down
            int index = this.ListBox1.SelectedIndex;
            int maxIndex = this.ListBox1.Items.Count - 1;
            if (index != maxIndex)
            {
                ListItem item = this.ListBox1.Items[index];
                this.ListBox1.Items.Remove(item);
                this.ListBox1.Items.Insert(index + 1, item);
            }

        }