using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data.Entity; using System.ComponentModel.DataAnnotations; using System.Data.Entity.ModelConfiguration; using System.Data.Entity.ModelConfiguration.Configuration;  namespace CodeFirstDemo {     /// <summary>     /// 实体注册Helper接口     /// </summary>     public interface IEntityRegstHelper     {         void RegTo(ConfigurationRegistrar confRegistrar);     }      // 客户     public class Customer     {         public int CustomerID { get; set; }         public String CustomerName { get; set; }         public string Address { get; set; }     }     // 客户实体的注册Helper     public class CustomerRegstHelper : IEntityRegstHelper     {         public void RegTo(ConfigurationRegistrar confRegistrar)         {             confRegistrar.Add<Customer>(new EntityTypeConfiguration<Customer>());         }     }               public class MyDbContext : DbContext     {         List<IEntityRegstHelper> entityRegstHelperlist;         // 添加实体注册         public void AddEntityRegHelper(IEntityRegstHelper r)         {             if (entityRegstHelperlist == null)                 entityRegstHelperlist = new List<IEntityRegstHelper>();             entityRegstHelperlist.Add(r);         }              //public DbSet<Customer> Customers { get; set; }         protected override void OnModelCreating(DbModelBuilder modelBuilder)         {             // 动态地加入实体             if (entityRegstHelperlist != null)             {                 foreach (IEntityRegstHelper r in entityRegstHelperlist)                     r.RegTo(modelBuilder.Configurations);             }         }     }          class Program     {         static void Main(string[] args)         {             using (var db = new MyDbContext())             {                 db.AddEntityRegHelper(new CustomerRegstHelper());                                  var c = new Customer()                 {                     CustomerName = "长沙市大风通讯有限公司",                     Address = "长沙市"                 };                 db.Set<Customer>().Add(c);                 db.SaveChanges();                  var query = from customer in db.Set<Customer>()                             select customer;                 foreach (var cq in query)                 {                     Console.WriteLine("客户: {0}, 地址：{1}", cq.CustomerName, cq.Address);                 }                                  Console.WriteLine("按任意键退出");                 Console.ReadKey();             }         }     } }