关于简单的三层的简化（bll,dal,model）的封装这里全部都在一个文件主要在于明白意思

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace 封装泛型CRUD
{
    public class TeacherInfoDAL<T> : BaseDAL<T> where T : new()
    {
        public override T Add(T obj)
        {
            Console.WriteLine("TeacherInfoDAL添加了一个对象");
           return base.Add(obj);
           

        }

        public override int Del(T obj)
        {
            Console.WriteLine("TeacherInfoDAL删除了一个对象");
            return base.Del(obj);

        }

        public override T Update(T obj)
        {
            Console.WriteLine("TeacherInfoDAL更新了一个对象");
            return base.Update(obj);
        }

        public override IList<T> QueryList(Func<T, bool> whereLambada)
        {
            Console.WriteLine("TeacherInfoDAL查询了系列个对象");
            return base.QueryList(whereLambada);
        }
    }
    public class UserInfoDAL<T> : BaseDAL<T> where T : new()
    {
        public override  T Add(T obj)
        {
            Console.WriteLine("UserInfoDAL添加了一个对象");
            base.Add(obj);
            return obj;

        }

        public override int Del(T obj)
        {
            Console.WriteLine("UserInfoDAL删除了一个对象");
           return  base.Del(obj);
          
        }

        public override T Update(T obj)
        {
            Console.WriteLine("UserInfoDAL更新了一个对象");
            return base.Update(obj);
        }

        public override IList<T> QueryList(Func<T, bool> whereLambada)
        {
            Console.WriteLine("UserInfoDAL查询了系列个对象");
          return  base.QueryList(whereLambada);
        }
    }

    public class BaseDAL<T> where T : new()
    {
        public virtual T Add(T obj)
        {
           
            return obj;
        }

        public virtual int Del(T obj)
        {
          
            return 0;
        }

        public virtual T Update(T obj)
        {
           
            return new T();
        }

        public virtual IList<T> QueryList(Func<T,bool> whereLambada )
        {
           

            IList<T> list = new List<T>();
            foreach (var r in list)
            {
                if (whereLambada(r))
                {
                    list.Add(r);
                }
            }
            return list;
        }

    }

    public abstract class BaseBLL<T> where T : new()
    {
        public BaseDAL<T> basedal;

        public virtual T Add(T obj)
        {
            Console.WriteLine("基本业务处理add");
            return new T();
        }

        public virtual int Del(T obj)
        {
            Console.WriteLine("基本业务处理del");
            return 0;
        }

        public virtual T Update(T obj)
        {
            Console.WriteLine("基本业务处理update");
           return new T();
        }

        public virtual IList<T> QueryList(Func<T, bool> whereLambada)
        {
            Console.WriteLine("基本业务处理QueryList");
           return new List<T>();
        }

        public abstract void setDAL( );

    }

    public class UserInfoBLL<T>:BaseBLL<T> where T : new()
    {
        public UserInfoBLL()
        {
            setDAL();
        }

        public override T Add(T obj)
        {
            base.Add(obj);
            Console.WriteLine("UserInfoBLL务处理add");
            return basedal.Add(obj);
        }

        public override int Del(T obj)
        {
            base.Del(obj);
            Console.WriteLine("UserInfoBLL务处理del");
          
            return basedal.Del(obj);
        }

        public override T Update(T obj)
        {
            base.Update(obj);
            Console.WriteLine("UserInfoBLL务处理update");
            return basedal.Update(obj);
        }

        public override IList<T> QueryList(Func<T, bool> whereLambada)
        {
            base.QueryList(whereLambada);
            Console.WriteLine("UserInfoBLL务处理querylist");
            return basedal.QueryList(whereLambada);
        }

        public override void setDAL()
        {
            basedal=new UserInfoDAL<T>();
        }
    }

    public class TeacheInfoBLL<T> : BaseBLL<T> where T : new()
    {
        public TeacheInfoBLL()
        {
            setDAL();
        }

        public override void setDAL()
        {
            basedal=new TeacherInfoDAL<T>();
           
        }
        public override T Add(T obj)
        {
            base.Add(obj);
            Console.WriteLine("TeacheInfoBLL务处理add");
            return basedal.Add(obj);
        }

        public override int Del(T obj)
        {
            base.Del(obj);
            Console.WriteLine("TeacheInfoBLL务处理del");

            return basedal.Del(obj);
        }

        public override T Update(T obj)
        {
            base.Update(obj);
            Console.WriteLine("TeacheInfoBLL务处理update");
            return basedal.Update(obj);
        }

        public override IList<T> QueryList(Func<T, bool> whereLambada)
        {
            base.QueryList(whereLambada);
            Console.WriteLine("TeacheInfoBLL务处理querylist");
            return basedal.QueryList(whereLambada);
        }


    }

    class Program
    {
        static void Main(string[] args)
        {
            BaseBLL<Student> bll=new TeacheInfoBLL<Student>();
            Student student=new Student();
            student.StudentNo = 1;
            bll.Add(new Student());
            bll.Del(new Student());
            bll.Update(new Student());
            bll.QueryList(a => a.StudentNo != 0);
            Console.WriteLine("------------------------");
            BaseBLL<Teacher> bll2 = new UserInfoBLL<Teacher>();
            Teacher t = new Teacher();
            t.TeacherNO = 1;
            bll2.Add(t);
            bll2.Del(t);
            bll2.Update(t);
            bll2.QueryList(a => a.TeacherNO != 0);
            Console.ReadKey();
        }
    }

    public class Student
    {
        public int StudentNo { get; set; }
        public string Name { get; set; }
        public string Sex { get; set; }
        public int Age { get; set; }
        public string Address { get; set; }
        public string Class { get; set; }
        public string DeptNO { get; set; }
    }

    public class Teacher
    {
        public int TeacherNO { get; set; }
        public string Name { get; set; }
        public string Sex { get; set; }
        public int Age { get; set; }
        public string DeptNo { get; set; }
    }
}