EF的Code First开始模式时，在设计Data层与Data First模式稍微有些不同，它主要有数据库类,数据库操作基类，数据通用操作接口和数据通过操作实现组成，每个类有自己的用途，先看一下最简单的结构：

DataContext是ＥＦ的数据库对象类型，它里面的代码构架了我们的数据表对象

public class DataContext : DbContext, IDataContext    {        #region Properties        /// 
        /// 得ì?到ì?UserBase结¨￠果?集?￥        /// 
        public IDbSet
    
      UserBases { get; private set; }        /// 
     
        /// 得ì?到ì?UserInfo结¨￠果?集?￥        /// 
        public IDbSet
     
       UserInfos { get; private set; }        /// 
      
        /// 得ì?到ì?Category结¨￠果?集?￥        /// 
        public IDbSet
      
        Categorys { get; private set; }        #endregion        #region Constructors        public DataContext()            : base(DataContext.GetConnectionString())        {            InitDbSets();        }        public DataContext(string cs)            : base(cs)        {            InitDbSets();        }        #endregion        #region  Private Methods        private void InitDbSets()        {            UserBases = this.Set
       
        ();            UserInfos = this.Set
        
         ();            Categorys = this.Set
         
          (); Init();//数oy据Y库a与??DBContext依°¨¤附?方¤?式o?　? } /// 
          
 /// 得ì?到ì?数oy据Y连￠?接¨?串?? /// 
 /// 
           private static string GetConnectionString() { string conn; if (System.Diagnostics.Debugger.IsAttached) { conn = VConfigs.WebInfoConfig.Get_Config().DevsSqlConn; } else { conn = VConfigs.WebInfoConfig.Get_Config().ReleaseSqlConn; } return conn; } /// 
          
 /// 根¨′据Y传??入¨?的ì?类¤¨¤型¨a，ê?进?行DDBContext出?始o?化?￥ /// 
 /// 
           private static void SetInitializer(InitializerTypes InitType) { switch (InitType) { case InitializerTypes.Standard: Database.SetInitializer(new CreateDatabaseIfNotExists
          
           ()); break; case InitializerTypes.ReCreateAlways: Database.SetInitializer(new DropCreateDatabaseAlways
           
            ()); break; case InitializerTypes.ReCreateByChange: Database.SetInitializer(new DropCreateDatabaseIfModelChanges
            
             ()); break; default: break; } } /// 
             
 /// DBContext初?始o?化?￥方¤?法¤?§ /// 
 private static void Init() { Database.DefaultConnectionFactory = new SqlConnectionFactory(); if (System.Diagnostics.Debugger.IsAttached) { DataContext.SetInitializer(InitializerTypes.ReCreateByChange); } else { DataContext.SetInitializer(InitializerTypes.Standard); } } #endregion /// 
             
 /// 数oy据Y库a建?§立￠?é时o?à执??行D /// 
 /// 
              protected override void OnModelCreating(DbModelBuilder modelBuilder) { } }
            
           
          
         
        
       
      
     
    

其中dataBase就是数据库操作基类，主要实现创建dbcontext对象和对修改进行统一提交的作用

/// 
    /// 数oy据Y库a基¨′类¤¨¤    /// 
    public abstract class DataBase    {        #region 单ì￡¤件t模?ê式o?创???建?§一°?个?类¤¨¤对?象¨?        /// 
        /// 数oy据Y源??对?象¨?        /// 
        private static DataContext _db = null;        protected static DataContext CreateInstance()        {            if (_db == null)                _db = new DataContext();            return _db;        }        #endregion        /// 
        /// 数oy据Y库a访¤?问¨o对?象¨?        /// 
        protected DataContext Db = CreateInstance();        /// 
        /// 统a3一°?提?¨￠交?动?￥作á??        /// 
        protected virtual void SubmitChanges()        {            try            {                Db.SaveChanges();            }            catch (Exception ex)            {                throw;            }        }    }

而数据操作统一接口主要实现对数据库的ＣＵＲＤ操作，代码一般是这样（与其它构架大同小异）

/// 
    /// 通a?§用??数oy据Y库a访¤?问¨o接¨?口¨2    /// 
    public interface IRepository
    
      where TEntity : Entity.BaseEntity    {        /// 
     
        /// 根¨′据Y数oy据Y库a实o|ì体??-a》?¤更¨1新?记?录?        /// 
        /// 
             void Update(TEntity entity);         /// 
     
        /// 根¨′据Y数oy据Y库a实o|ì体??-a》?¤[批¨2量￠?]更¨1新?记?录?        /// 
        /// 
             void Update(IList
     
       list);               /// 
      
        /// 根¨′据Y数oy据Y库a实o|ì体??-a》?¤插?入¨?记?录?        /// 
        void Insert(TEntity entity);        /// 
      
        /// 根¨′据Y数oy据Y库a实o|ì体??-a》?¤[批¨2量￠?]插?入¨?记?录?        /// 
        void Insert(IList
      
        list);        /// 
       
        /// 根¨′据Y数oy据Y库a实o|ì体??-a》?¤插?入¨?记?录?并?é返¤|ì回?刚?刚?立￠?é即??插?入¨?的ì?状á??态??视o¨?图a?        /// 
        TEntity InsertGetIDENTITY(TEntity entity);        /// 
       
        /// 根¨′据Y数oy据Y库a实o|ì体??-a》?¤多¨¤主??键¨1,删|?除y有?D多¨¤个?参?数oy控?制?的ì?对?象¨?        /// 
        /// 
               void Delete(TEntity entity);        /// 
       
        /// 返¤|ì回?默?认¨?结¨￠果?集?￥        /// 
        /// 
               IQueryable
       
         GetModel();        /// 
        
        /// 根¨′据Y主??键¨1返¤|ì回?实o|ì体??        /// 
        /// 
                TEntity GetModelById(int id);    }
       
      
     
    

事实上我们真实的datacontext对象在实现开发中只有Data本层可见，而对于业务层和ＵＩ层是不被容许访问的，当然这也是保存原数据对象及方便扩展和维护的一种作法。

本文转自博客园张占岭（仓储大叔）的博客，原文链接：，如需转载请自行联系原博主。