从网上下载一个网站,说是三层结构,可是不知道这样设计有什么好处.望哪位大侠不吝赐教.
    public class BaseEntity

public interface IBaseDAL<T> where T : BaseEntity  

    public abstract class BaseDAL<T> : IBaseDAL<T> where T : BaseEntity, new()

public class BaseBLL<T> where T : BaseEntity, new()

 public class User:BaseEntity

 idal:public interface User : IBaseDAL<MSFrame.Main.Entity.User>

 dal:public class User : BaseDAL<MSFrame.Main.Entity.User>, Jide.MSFrame.Main.IDAL.User

bll:public class User:BaseBLL<MSFrame.Main.Entity.User>

 public class BLLFactory<T> where T : class

使用时大概就是这样的:

Entity.User model = new MSFrame.Main.Entity.User();

BLLFactory<MSFrame.Main.BLL.User>.Instance.Insert2(model);

我想知道为什么要定义以上这些类,这些类有什么作用,这样有什么好处.

没专家分了,望大侠们不吝赐教.