禁用或启用DropDownList的Items

此篇算是对http://www.2cto.com/kf/201204/127918.html重构升级。
因为网友需要不但能禁用还能可以启用DropDownList的Items。为了不想用户写太多代码。Insus.NET写了一个类别，并让它继承了System.Web.UI.WebControls命名空间下的DropDownList. 可从下图看到InsusDropDownList实例化并传入DropDownList控件，然后实例化之后的对象，就是可以使用highlight的四个方法DisableImsByText(), DisabletemsByVue() ,EnableItemsBText(), EnableItemsByValue()。

InsusDropDownList类别：
  InsusDropDownList
 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI.WebControls;

/// <summary>
/// Summary description for InsusDropDownList
/// </summary>
namespace Insus.NET
{
    public class InsusDropDownList : DropDownList
    {
        DropDownList _DropDownList;

        public InsusDropDownList(DropDownList dropDownList)
        {
            this._DropDownList = dropDownList;
        }

        public void DisableItemsByText(string text)
        {         
            DisableItems(GetIndexByText(text));
        }

        public void EnableItemsByText(string text)
        {           
            EnableItems(GetIndexByText(text));
        }

        public void DisableItemsByValue(string value)
        {          
            DisableItems(GetIndexByValue(value));
        }

        public void EnableItemsByValue(string value)
        {           
            EnableItems(GetIndexByValue(value));
        }

        private int GetIndexByText(string text)
        {
            return this._DropDownList.Items.IndexOf(this._DropDownList.Items.FindByText(text));