EF--封裝三層架構IOC-有解無憂

為什么分層？

不分層封裝的話，下面的代碼就是上端直接依賴于下端，也就是UI層直接依賴于資料訪問層，分層一定要依賴抽象，滿足依賴倒置原則，所以我們要封裝，要分層

下面這張圖和傳統的三層略有不同，不同之處在于，UI層不直接依賴于業務邏輯層，而是UI層依賴于業務邏輯抽象層IBLL，業務邏輯層不直接依賴于資料訪問層，而是業務邏輯層依賴于資料訪問抽象層IDAL

{
    SchoolDBEntities dbContext = new SchoolDBEntities();
    dbContext.Set<Student>().Where(s=>s.Student_ID == "0000000001");
}

封裝分層

1、David.General.EF.Bussiness.Interface（IBLL--業務邏輯抽象層）

繼承IDisposable的目的是為了可以使用using，是為了釋放Context

IBaseService相當于上圖的IBLL（業務邏輯抽象層），DAL已經不存在了，因為EF已經取代了DAL層

namespace David.General.EF.Bussiness.Interface
{
    public interface IBaseService : IDisposable//可以使用using，是為了釋放Context
    {
        #region Query
        /// <summary>
        /// 根據id主鍵查詢物體
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        T Find<T>(object id) where T : class;

        /// <summary>
        /// 提供對單表的查詢
        /// 不推薦對外直接開放
        ///IQueryable支持運算式目錄樹
        /// </summary>
        /// <returns>IQueryable型別集合</returns>
        [Obsolete("盡量避免使用，using 帶運算式目錄樹的 代替")]
        IQueryable<T> Set<T>() where T : class;

        /// <summary>
        /// 查詢，傳入運算式目錄樹
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="funcWhere">運算式目錄樹</param>
        /// <returns>IQueryable型別集合</returns>
        IQueryable<T> Query<T>(Expression<Func<T, bool>> funcWhere) where T : class;

        /// <summary>
        /// 分頁查詢
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <typeparam name="S"></typeparam>
        /// <param name="funcWhere"></param>
        /// <param name="pageSize"></param>
        /// <param name="pageIndex"></param>
        /// <param name="funcOrderby"></param>
        /// <param name="isAsc"></param>
        /// <returns></returns>
        PageResult<T> QueryPage<T, S>(Expression<Func<T, bool>> funcWhere, int pageSize, int pageIndex, Expression<Func<T, S>> funcOrderby, bool isAsc = true) where T : class;
        #endregion

        #region Add
        /// <summary>
        /// 新增資料
        /// </summary>
        /// <param name="t"></param>
        /// <returns>回傳帶主鍵的物體</returns>
        T Insert<T>(T t) where T : class;

        /// <summary>
        /// 新增資料
        /// 多條sql 一個連接，事務插入
        /// </summary>
        /// <param name="tList"></param>
        IEnumerable<T> Insert<T>(IEnumerable<T> tList) where T : class;
        #endregion

        #region Update
        /// <summary>
        /// 更新資料
        /// </summary>
        /// <param name="t"></param>
        void Update<T>(T t) where T : class;

        /// <summary>
        /// 更新資料
        /// </summary>
        /// <param name="tList"></param>
        void Update<T>(IEnumerable<T> tList) where T : class;
        #endregion

        #region Delete
        /// <summary>
        /// 根據主鍵洗掉資料
        /// </summary>
        /// <param name="t"></param>
        void Delete<T>(int Id) where T : class;

        /// <su+mary>
        /// 洗掉資料
        /// </summary>
        /// <param name="t"></param>
        void Delete<T>(T t) where T : class;

        /// <summary>
        /// 洗掉資料
        /// </summary>
        /// <param name="tList"></param>
        void Delete<T>(IEnumerable<T> tList) where T : class;
        #endregion

        #region Other
        /// <summary>
        /// 立即保存全部修改
        /// 把增/刪的savechange給放到這里，是為了保證事務的
        /// </summary>
        void Commit();

        /// <summary>
        /// 執行sql 回傳集合
        /// </summary>
        /// <param name="sql"></param>
        /// <param name="parameters"></param>
        /// <returns></returns>
        IQueryable<T> ExcuteQuery<T>(string sql, SqlParameter[] parameters) where T : class;

        /// <summary>
        /// 執行sql，無回傳
        /// </summary>
        /// <param name="sql"></param>
        /// <param name="parameters"></param>
        void Excute<T>(string sql, SqlParameter[] parameters) where T : class;
        #endregion
    }
}

public class PageResult<T>
{
    public int TotalCount { get; set; }
    public int PageIndex { get; set; }
    public int PageSize { get; set; }
    public List<T> DataList { get; set; }
}

2、David.General.EF.Bussiness.Service（業務邏輯實作層）

namespace David.General.EF.Bussiness.Service
{
    public class BaseService : IBaseService
    {
        #region Identity
        /// <summary>
        /// protected--保證只有子類可以看得見
        /// { get; private set; }--保證只有子類可以獲取，子類不能修改，只有自己可以修改
        /// </summary>
        protected DbContext Context { get; private set; }
        
       /// <summary>
        /// 建構式注入
        /// 一個請求一個，不能全域一個，應該一個實體一個
        /// </summary>
        /// <param name="context"></param>
        public BaseService(DbContext context)
        {
            this.Context = context;
        }
        #endregion Identity

        #region Query
        /// <summary>
        /// 通過Id得到物體
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="id"></param>
        /// <returns></returns>
        public T Find<T>(object id) where T : class
        {
            return this.Context.Set<T>().Find(id);
        }

        /// <summary>
        /// 不應該暴露給上端使用者，盡量少用
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <returns></returns>
        [Obsolete("盡量避免使用，using 帶運算式目錄樹的代替")]
        public IQueryable<T> Set<T>() where T : class
        {
            return this.Context.Set<T>();
        }

        /// <summary>
        /// 這才是合理的做法，上端給條件，這里查詢
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="funcWhere"></param>
        /// <returns></returns>
        public IQueryable<T> Query<T>(Expression<Func<T, bool>> funcWhere) where T : class
        {
            return this.Context.Set<T>().Where<T>(funcWhere);
        }

        /// <summary>
        /// 分頁查詢
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <typeparam name="S"></typeparam>
        /// <param name="funcWhere">查詢條件運算式目錄樹</param>
        /// <param name="pageSize">頁大小</param>
        /// <param name="pageIndex">頁索引</param>
        /// <param name="funcOrderby">按什么欄位排序</param>
        /// <param name="isAsc">升序還是降序</param>
        /// <returns></returns>
        public PageResult<T> QueryPage<T, S>(Expression<Func<T, bool>> funcWhere, int pageSize, int pageIndex, Expression<Func<T, S>> funcOrderby, bool isAsc = true) where T : class
        {
            var list = this.Set<T>();
            if (funcWhere != null)
            {
                list = list.Where<T>(funcWhere);
            }
            if (isAsc)
            {
                list = list.OrderBy(funcOrderby);
            }
            else
            {
                list = list.OrderByDescending(funcOrderby);
            }
            PageResult<T> result = new PageResult<T>()
            {
                DataList = list.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList(),
                PageIndex = pageIndex,
                PageSize = pageSize,
                TotalCount = this.Context.Set<T>().Count(funcWhere)
            };
            return result;
        }
        #endregion

        #region Insert
        /// <summary>
        /// 插入
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="t"></param>
        /// <returns></returns>
        public T Insert<T>(T t) where T : class
        {
            this.Context.Set<T>().Add(t);
            return t;
        }

        /// <summary>
        /// 插入集合
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="tList"></param>
        /// <returns></returns>
        public IEnumerable<T> Insert<T>(IEnumerable<T> tList) where T : class
        {
            this.Context.Set<T>().AddRange(tList);
            return tList;
        }
        #endregion

        #region Update
        /// <summary>
        /// 是沒有實作查詢，直接更新的,需要Attach和State
        /// 
        /// 如果是已經在context，只能再封裝一個(在具體的service)
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="t"></param>
        public void Update<T>(T t) where T : class
        {
            if (t == null) throw new Exception("t is null");

            this.Context.Set<T>().Attach(t);//將資料附加到背景關系，支持物體修改和新物體，重置為UnChanged
            this.Context.Entry<T>(t).State = EntityState.Modified;//全欄位更新
        }

        /// <summary>
        /// 集合修改
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="tList"></param>
        public void Update<T>(IEnumerable<T> tList) where T : class
        {
            foreach (var t in tList)
            {
                this.Context.Set<T>().Attach(t);
                this.Context.Entry<T>(t).State = EntityState.Modified;
            }
        }
        
        /// <summary>
        /// 更新資料，指定更新哪些列，哪怕有些列值發生了變化，沒有指定列也不能修改
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="t"></param>
        public void UpdateSpecifyFiled<T>(T t, List<string> filedList) where T : class
        {
            this.Context.Set<T>().Attach(t);//將資料附加到背景關系
            foreach(var filed in filedList)
            {
                this.Context.Entry<T>(t).Property(filed).IsModified = true;//指定某欄位被改過
            }
        }
        #endregion

        #region Delete
        /// <summary>
        /// 先附加 再洗掉
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="t"></param>
        public void Delete<T>(T t) where T : class
        {
            if (t == null) throw new Exception("t is null");
            this.Context.Set<T>().Attach(t);
            this.Context.Set<T>().Remove(t);
        }

        /// <summary>
        /// 還可以增加非即時commit版本的，
        /// 做成protected
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="Id"></param>
        public void Delete<T>(int Id) where T : class
        {
            T t = this.Find<T>(Id);//也可以附加
            if (t == null) throw new Exception("t is null");
            this.Context.Set<T>().Remove(t);
        }

        /// <summary>
        /// 洗掉集合
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="tList"></param>
        public void Delete<T>(IEnumerable<T> tList) where T : class
        {
            foreach (var t in tList)
            {
                this.Context.Set<T>().Attach(t);
            }
            this.Context.Set<T>().RemoveRange(tList);
        }
        #endregion

        #region Other
        /// <summary>
        /// 一次性提交
        /// </summary>
        public void Commit()
        {
            this.Context.SaveChanges();
        }

        /// <summary>
        /// sql陳述句查詢
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="sql"></param>
        /// <param name="parameters"></param>
        /// <returns></returns>
        public IQueryable<T> ExcuteQuery<T>(string sql, SqlParameter[] parameters) where T : class
        {
            return this.Context.Database.SqlQuery<T>(sql, parameters).AsQueryable();
        }

        /// <summary>
        /// 執行sql陳述句
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="sql"></param>
        /// <param name="parameters"></param>
        public void Excute<T>(string sql, SqlParameter[] parameters) where T : class
        {
            DbContextTransaction trans = null;
            try
            {
                trans = this.Context.Database.BeginTransaction();
                this.Context.Database.ExecuteSqlCommand(sql, parameters);
                trans.Commit();
            }
            catch (Exception ex)
            {
                if (trans != null)
                    trans.Rollback();
                throw ex;
            }
        }

        public virtual void Dispose()
        {
            if (this.Context != null)
            {
                this.Context.Dispose();
            }
        }
        #endregion
    }
}

整合Unity，實作IOC，依賴注入解決問題

雖然封裝完了，但是還是帶來了2個問題，問題如下代碼所示，所以我們需要解決下面兩個問題
問題1：通過封裝，完成了通過Service來完成對資料庫的訪問，但是右邊 new StudentService()是細節，不滿足依賴倒置原則，應該面向抽象編程
問題2：構造new StudentService()的時候需要一個Context，不能每次都SchoolDBEntities dbContext = new SchoolDBEntities();

{
    SchoolDBEntities dbContext = new SchoolDBEntities();
    using (IStudentService iStudentService = new StudentService(dbContext))
    {
        Student student = iStudentService.Find<Student>("0000000001");

        Student student1 = new Student();
        student1.Student_ID = "1111111";
        student1.Student_Name = "Student1";
        iStudentService.Insert(student1);

        iStudentService.Commit();
    }
}

1、Nuget引入Unity相關dll

2、配置Unity.Config

.2.1、給BaseService注入DbContext

type中逗號前是完整型別名稱，也就是命名空間System.Data.Entity+類名DbContext，逗號后是dll名稱EntityFramework

mapTo中逗號前是完整型別名稱，也就是命名空間David.General.EF.Model+類名SchoolDBEntities，逗號后是dll名稱David.General.EF.Model

2.2、給IStudentService注入StudentService

type中逗號前是完整型別名稱，也就是命名空間David.General.EF.Bussiness.Interface+介面名IStudentService，逗號后是dll名稱David.General.EF.Bussiness.Interface

mapTo中逗號前是完整型別名稱，也就是命名空間David.General.EF.Bussiness.Service+類名StudentService，逗號后是dll名稱David.General.EF.Bussiness.Service

<configuration>
  <configSections>
    <section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection, Unity.Configuration"/>
  </configSections>
  <unity>
    <sectionExtension type="Microsoft.Practices.Unity.InterceptionExtension.Configuration.InterceptionConfigurationExtension, Unity.Interception.Configuration"/>
    <containers>
      <container name="MyContainer">
        <extension type="Interception"/>
        <register type="System.Data.Entity.DbContext, EntityFramework" mapTo="David.General.EF.Model.SchoolDBEntities,David.General.EF.Model"/>
        <register type="David.General.EF.Bussiness.Interface.IStudentService,David.General.EF.Bussiness.Interface" mapTo="David.General.EF.Bussiness.Service.StudentService, David.General.EF.Bussiness.Service">
        </register>
      </container>
    </containers>
  </unity>
</configuration>

3、呼叫服務
如下呼叫代碼和截圖所示
首先：我們構建學生服務的時候，沒有出現細節StudentService
其次：在構建學生服務的時候，沒有顯式的去傳入DbContext，StudentService繼承BaseService，StudentService的建構式的引數DbContext是來源于BaseService，而BaseService依賴的DbContext是通過建構式注入進來的

{
　　//UnityConfig配置只用初始化一次，所以我們把讀取UnityConfig配置封裝一下
　　//使用單例模式，l利用靜態建構式只初始化1次的特點，達到配置只初始化1次
　　Unity.IUnityContainer container = ContainerFactory.GetContainer();

　　//IOC：去掉細節依賴，降低耦合，增強擴展性
　　using (IStudentService iStudentService = container.Resolve<IStudentService>())
　　{
　　　　Student student = iStudentService.Find<Student>("0000000001");

　　　　//測驗指定更新
　　　　Student oldStudent = new Student()
　　　　{
　　　　　　Student_ID = "0000020001",
　　　　　　Student_Name = "豬豬",
　　　　　　Student_Sex = "男"
　　　　};

　　　　List<string> filedList = new List<string>();
　　　　filedList.Add("Student_Name");
　　　　iStudentService.UpdateSpecifyFiled<Student>(oldStudent, filedList);
　　　　iStudentService.Commit();
　　}
}

namespace David.General.EF.Bussiness.Service
{
    public class StudentService : BaseService,IStudentService
    {
        public StudentService(DbContext context) : base(context)
        {
        }

        /// <summary>
        /// 記錄學生打架
        /// </summary>
        /// <param name="student"></param>
        public void RecordStudentFight(Student student)
        {
            base.Insert(student);
            this.Commit();
        }
    }
}

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