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 /// <summary> /// 得ì?到ì?UserBase结¨￠果?集?￥ /// </summary> public IDbSet<UserBase> UserBases { get; private set; } /// <summary> /// 得ì?到ì?UserInfo结¨￠果?集?￥ /// </summary> public IDbSet<UserInfo> UserInfos { get; private set; } /// <summary> /// 得ì?到ì?Category结¨￠果?集?￥ /// </summary> public IDbSet<Category> 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<UserBase>(); UserInfos = this.Set<UserInfo>(); Categorys = this.Set<Category>(); Init();//数oy据Y库a与??DBContext依°¨¤附?方¤?式o? ? } /// <summary> /// 得ì?到ì?数oy据Y连￠?接¨?串?? /// </summary> /// <returns></returns> 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; } /// <summary> /// 根¨′据Y传??入¨?的ì?类¤¨¤型¨a，ê?进?行DDBContext出?始o?化?￥ /// </summary> /// <param name="InitType"></param> private static void SetInitializer(InitializerTypes InitType) { switch (InitType) { case InitializerTypes.Standard: Database.SetInitializer(new CreateDatabaseIfNotExists<DataContext>()); break; case InitializerTypes.ReCreateAlways: Database.SetInitializer(new DropCreateDatabaseAlways<DataContext>()); break; case InitializerTypes.ReCreateByChange: Database.SetInitializer(new DropCreateDatabaseIfModelChanges<DataContext>()); break; default: break; } } /// <summary> /// DBContext初?始o?化?￥方¤?法¤?§ /// </summary> private static void Init() { Database.DefaultConnectionFactory = new SqlConnectionFactory(); if (System.Diagnostics.Debugger.IsAttached) { DataContext.SetInitializer(InitializerTypes.ReCreateByChange); } else { DataContext.SetInitializer(InitializerTypes.Standard); } } #endregion /// <summary> /// 数oy据Y库a建?§立￠?é时o?à执??行D /// </summary> /// <param name="modelBuilder"></param> 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
/// <summary> /// 数oy据Y库a基¨′类¤¨¤ /// </summary> public abstract class DataBase { #region 单ì￡¤件t模?ê式o?创???建?§一°?个?类¤¨¤对?象¨? /// <summary> /// 数oy据Y源??对?象¨? /// </summary> private static DataContext _db = null; protected static DataContext CreateInstance() { if (_db == null) _db = new DataContext(); return _db; } #endregion /// <summary> /// 数oy据Y库a访¤?问¨o对?象¨? /// </summary> protected DataContext Db = CreateInstance(); /// <summary> /// 统a3一°?提?¨￠交?动?￥作á?? /// </summary> 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）
/// <summary> /// 通a?§用??数oy据Y库a访¤?问¨o接¨?口¨2 /// </summary> public interface IRepository<TEntity> where TEntity : Entity.BaseEntity { /// <summary> /// 根¨′据Y数oy据Y库a实o|ì体??-a》?¤更¨1新?记?录? /// </summary> /// <param name="entity"></param> void Update(TEntity entity); /// <summary> /// 根¨′据Y数oy据Y库a实o|ì体??-a》?¤[批¨2量￠?]更¨1新?记?录? /// </summary> /// <param name="entity"></param> void Update(IList<TEntity> list); /// <summary> /// 根¨′据Y数oy据Y库a实o|ì体??-a》?¤插?入¨?记?录? /// </summary> void Insert(TEntity entity); /// <summary> /// 根¨′据Y数oy据Y库a实o|ì体??-a》?¤[批¨2量￠?]插?入¨?记?录? /// </summary> void Insert(IList<TEntity> list); /// <summary> /// 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? /// </summary> TEntity InsertGetIDENTITY(TEntity entity); /// <summary> /// 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¨? /// </summary> /// <param name="oArr"></param> void Delete(TEntity entity); /// <summary> /// 返¤|ì回?默?认¨?结¨￠果?集?￥ /// </summary> /// <returns></returns> IQueryable<TEntity> GetModel(); /// <summary> /// 根¨′据Y主??键¨1返¤|ì回?实o|ì体?? /// </summary> /// <returns></returns> 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。
