ASP.NET - List<> 绑定 DropDownList

代码：

         //声明泛型
         List<category> inof = new List<category>();//二级分类

         //声明类使用的对象类
         public class category
         {
             public category(string id, string name)
             {
                 Id = id;
                 Name = name;
             }

             private string id;

             public string Id
             {
                 get { return id; }
                 set { id = value; }
             }

             private string name;

             public string Name
             {
                 get { return name; }
                 set { name = value; }
             }
         }

         //获取信息
         public void selectdatabind()
         {
             SqlDataReader sdr = SQLHelper.ExcuteReader("select ID, CategoryName from Tb_APCategory where ParentID = 1000", CommandType.Text);
             while (sdr.Read())
             {
                 SqlDataReader sdr_2 = SQLHelper.ExcuteReader("select ID, CategoryName from Tb_APCategory where ParentID = " + sdr["ID"].ToString() + "", CommandType.Text);
                 while (sdr_2.Read())
                 {
                     inof.Add(new category(sdr_2["ID"].ToString(), sdr_2["CategoryName"].ToString()));
                 }
             }
         }

         //使用
         this.DropDownList2.DataSource = inof;
         this.DropDownList2.DataValueField = "ID";
         this.DropDownList2.DataTextField = "Name";
         this.DropDownList2.DataBind();