changedownlistselect.aspx.cs

来自「asp.net专家200问(含源代码解决法案」· CS 代码 · 共 84 行

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

namespace DropDownSelected
{
	/// <summary>
	/// WebForm1 的摘要说明。
	/// </summary>
	public class WebForm1 : System.Web.UI.Page
	{
		protected System.Web.UI.WebControls.Button Downbtn;
		protected System.Web.UI.WebControls.Button Upbtn;
		protected System.Web.UI.WebControls.DropDownList DropDown1;
		protected System.Web.UI.WebControls.Label Label1;
	
		private void Page_Load(object sender, System.EventArgs e)
		{
			// 在此处放置用户代码以初始化页面
		}

		#region Web Form Designer generated code
		override protected void OnInit(EventArgs e)
		{
			//
			// CODEGEN：该调用是 ASP.NET Web 窗体设计器所必需的。
			//
			InitializeComponent();
			base.OnInit(e);
		}
		
		/// <summary>
		/// 设计器支持所需的方法 - 不要使用代码编辑器修改
		/// 此方法的内容。
		/// </summary>
		private void InitializeComponent()
		{    
			this.Downbtn.Click += new System.EventHandler(this.Downbtn_Click);
			this.Upbtn.Click += new System.EventHandler(this.Upbtn_Click);
			this.Load += new System.EventHandler(this.Page_Load);

		}
		#endregion

		private void Downbtn_Click(object sender, System.EventArgs e)
		{
			int Index = DropDown1.SelectedIndex;
			int Count = DropDown1.Items.Count;
			if( Index < Count-1 )
			{
				DropDown1.SelectedIndex = Index+1;
				Upbtn.Enabled = true;
			} 
			if( Index == Count-2 )
			{
				DropDown1.SelectedIndex = Index+1;
				Downbtn.Enabled = false;
			}
		}

		private void Upbtn_Click(object sender, System.EventArgs e)
		{
			int Index = DropDown1.SelectedIndex;
			if( Index == 1)
			{
				DropDown1.SelectedIndex = Index-1;
				Upbtn.Enabled = false;
			}
			if( Index > 1 )
			{
				DropDown1.SelectedIndex = Index-1;
				Downbtn.Enabled = true;
			} 
		}
	}
}