在这片文章中，我将自己动手为所有的实体：写一个泛型仓储类，还有一个工作单元。
工作单元的职责就是：为每一个实体，创建仓储实例。仓储（仓库）的职责：增删查改的功能实现。
我们将会在控制器中，创建工作单元类（UnitOfWork）的实例，然后根据实体，创建仓储实例，再就是使用仓储里面的方法，做操作了。
下面的图中，解释了，仓储和EF 数据上文的关系，在这个图里面，MVC控制器和仓储之间的交互，是通过工作单元来进行的，而不是直接和EF接触。
那么你可能就要问了，为什么要使用工作单元？？？
工作单元，就像其名称一样，做某些事情。在这篇文章中，工作单元主要是，创建实例：它实例化数据上下文，然后使用同样的数据上下文对象，实例化每一个仓储对象，用来做数据库操作。所以：工作单元是一种模式，它确保我们所有的仓储类，使用同样数据库上下文。
实现一个泛型仓储类和一个工作单元
请注意：在这篇文章中，你的用户界面，使用具体的类，而不是接口，原因，我后面的一篇文章中，会说！
好了，现在开始实施：
在这篇文章中，我将会搭建4个项目。
MVC.Core---->>>类库项目【这里面：主要是实体的声明】
MVC.Data---->>>类库项目【这里面主要是数据库的操作，添加引用类库项目（MVC.Core）】
MVC.Repository--->>>类库项目【这里主要是定义泛型仓储类，添加引用MVC.Core和MVC.Data两个项目】
MVC.Web----->>>MVC WEB程序【Web程序UI，添加引用MVC.Core和MVC.Data还有MVC.Repository三个项目】
框架的界面：
首先来写实体层：在MVC.Core项目下，添加一个BaseEntity实体，添加如下代码：
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace MVC.Core{ public class BaseEntity { /// <summary> /// 编号 /// </summary> public Int64 ID { get; set; } /// <summary> /// 添加时间 /// </summary> public DateTime AddedTime { get; set; } /// <summary> /// 修改时间 /// </summary> public DateTime ModifiedTime { get; set; } /// <summary> /// IP地址 /// </summary> public string IP { get; set; } }}
然后，在MVC.Core项目下，新建一个文件夹【Data】,在【Data】文件夹里面添加Book实体，Book继承BaseEntity实体。
下面是Book实体里面的代码：
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace MVC.Core.Data{ public class Book:BaseEntity { /// <summary> /// 书名 /// </summary> public string Title { get; set; } /// <summary> /// 作者 /// </summary> public string Author { get; set; } /// <summary> /// ISBN编号 /// </summary> public string ISBN { get; set; } /// <summary> /// 发布时间 /// </summary> public DateTime PublishedTime { get; set; } }}
然后，我们看到MVC.Data这个类库项目，这个项目中，我们将会包含数据上下文类，Book实体的映射。
ADO.NET Entity Framework 要求我们创建的数据上下文类必须继承DbContext类。我们在上下文类中，将会重写OnModelCreating方法，这个方法是用来使用Code-First方式，配置实体类的。
使用EF，需要安装EF，这里就不介绍了，要了解的话，可以去看我前面的文章中的介绍。
我创建一个EFDbContextClass类，下面是数据上下文类中的代码：
using MVC.Core;using System;using System.Collections.Generic;using System.Data.Entity;using System.Data.Entity.ModelConfiguration;using System.Linq;using System.Reflection;using System.Text;using System.Threading.Tasks;namespace MVC.Data{ public class EFDBContextClass:DbContext { public EFDBContextClass() : base("name=ConnectionStrings") { } public new IDbSet<TEntity> Set<TEntity>() where TEntity:BaseEntity { return base.Set<TEntity>(); } protected override void OnModelCreating(DbModelBuilder modelBuilder) {
var typesToRegister = Assembly.GetExecutingAssembly().GetTypes() .Where(type => !String.IsNullOrEmpty(type.Namespace)) .Where(type => type.BaseType != null && type.BaseType.IsGenericType && type.BaseType.GetGenericTypeDefinition() == typeof(EntityTypeConfiguration<>)); foreach (var type in typesToRegister) { dynamic configurationInstance = Activator.CreateInstance(type); modelBuilder.Configurations.Add(configurationInstance); } base.OnModelCreating(modelBuilder); } }}
在上面的代码中，使用反射来映射每个实体。然后数据上下文的构造函数中，我传递了连接字符串名字ConnectionStrings,在配置文件中
<connectionStrings> <add name="ConnectionStrings" connectionString="server=.;database=MyRepositoryDB;uid=sa;pwd=Password_1" providerName="System.Data.SqlClient"/> </connectionStrings>
好了，数据上下文也写好了，现在开始实体映射吧，在MVC.Data项目中，添加一个文件夹--【Mapping】，然后在Mapping文件夹下面，添加一个类--【BookMap】，下面是BookMap的代码：
using MVC.Core.Data;using System;using System.Collections.Generic;using System.Data.Entity.ModelConfiguration;using System.Linq;using System.Text;using System.Threading.Tasks;using System.ComponentModel.DataAnnotations.Schema;namespace MVC.Data.Mapping{ public class BookMap:EntityTypeConfiguration<Book> { public BookMap() { //配置主键 HasKey(s => s.ID); //配置列 Property(s => s.ID).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity); Property(p => p.Title).IsRequired(); Property(p => p.ISBN).IsRequired(); Property(p => p.Author).IsRequired(); Property(p => p.AddedTime).IsRequired(); Property(p => p.ModifiedTime).IsRequired(); Property(p => p.PublishedTime).IsRequired(); Property(p => p.IP); //配置表名称 ToTable("Books"); } }}
好了，现在开始写我们的泛型仓储类，在我们的MVC.Repository项目中，添加一个类Repository。这里没有添加接口仓储，是为了更好的理解。泛型仓储类拥有增删查改的方法，
这个仓储类，拥有一个带数据上下文类的参数的构造函数，所以当我们创建创建仓储实例的时候，只需要传递一个数据上下文对象过来就行，这就一样，每个实体的仓储都有一样的数据上下文对象了。下面的代码是，泛型仓储模式代码了：
using MVC.Core;using MVC.Data;using System;using System.Collections.Generic;using System.Data.Entity;using System.Data.Entity.Validation;using System.Linq;using System.Text;using System.Threading.Tasks;namespace MVC.Repository{ public class Repository<T> where T:BaseEntity { private EFDBContextClass context; private IDbSet<T> entities; string errorMessage = string.Empty; public Repository(EFDBContextClass context) { this.context = context; } public T GetById(object id) { return this.Entities.Find(id); } public void Insert(T entity) { try { if (entity == null) { throw new ArgumentNullException("entity"); } this.Entities.Add(entity); this.context.SaveChanges(); } catch (DbEntityValidationException ex) { //错误处理机制 foreach (var validationErros in ex.EntityValidationErrors) { foreach (var errorInfo in validationErros.ValidationErrors) { errorMessage += string.Format("属性:{0} 错误消息:{1}", errorInfo.PropertyName, errorInfo.ErrorMessage)
+ Environment.NewLine; } } throw new Exception(errorMessage, ex); } } public void Update(T entity) { try { if (entity == null) { throw new ArgumentNullException("entity"); } this.context.SaveChanges(); } catch (DbEntityValidationException ex) { foreach (var errorItems in ex.EntityValidationErrors) { foreach (var errorinfo in errorItems.ValidationErrors) { errorMessage += string.Format("属性名:{0},错误消息:{1}", errorinfo.PropertyName, errorinfo.ErrorMessage)
+ Environment.NewLine; } } throw new Exception(errorMessage, ex); } } public void Delete(T entity) { try { if (entity == null) { throw new ArgumentNullException("entity"); } this.Entities.Remove(entity); this.context.SaveChanges(); } catch (DbEntityValidationException ex) { foreach (var errorItems in ex.EntityValidationErrors) { foreach (var errorinfo in errorItems.ValidationErrors) { errorMessage += string.Format("属性名:{0},错误消息:{1}", errorinfo.PropertyName, errorinfo.ErrorMessage)
+ Environment.NewLine; } } throw new Exception(errorMessage, ex); } } private IDbSet<T> Entities { get { if (entities == null) { entities = context.Set<T>(); } return entities; } } public virtual IQueryable<T> Table { get { return this.Entities; } } }}
在MVC.Repository项目中添加一个类：UnitOfWork
现在来为工作单元创建一个类，UnitOfWork，这个类继承IDisposible接口，所以它的每个实例将会在控制器中销毁，这个工作单元，初始化程序的数据上下文类【EFDBContextClass】.这个工作单元类的核心就是Repository方法，这个方法，为每一个继承自BaseEntity的实体，返回一个仓储【repository】对象，下面是工作单元类的代码：
using MVC.Core;using MVC.Data;using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace MVC.Repository{ public class UnitOfWork:IDisposable { private readonly EFDBContextClass context; private bool disposed; private Dictionary<string, object> repositories; public UnitOfWork(EFDBContextClass context) { this.context = context; } public UnitOfWork() { context = new EFDBContextClass(); } public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } public void Save() { context.SaveChanges(); } public virtual void Dispose(bool disposing) { if (!disposed) { if (disposing) { context.Dispose(); } } disposed = true; } public Repository<T> Repository<T>() where T : BaseEntity { if (repositories == null) { repositories = new Dictionary<string, object>(); } var type = typeof(T).Name; if (!repositories.ContainsKey(type)) { var repositoryType = typeof(Repository<>); var repositoryInstance = Activator.CreateInstance(repositoryType.MakeGenericType(typeof(T)), context); repositories.Add(type, repositoryInstance); } return (Repository<T>)repositories[type]; } }}
到此，现在底层的代码,基本都写好了。
现在开始MVC.Web项目里面的代码：
首先，我们在控制器文件夹下面，新建一个控制器类，BookController。然后，我们创建工作单元的实例。
下面是BookController控制器的代码：
using MVC.Core.Data;using MVC.Data;using MVC.Repository;using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.Mvc;namespace MVC.Web.Controllers{ public class BookController : Controller { private UnitOfWork unitOfWork = new UnitOfWork(); private Repository<Book> bookRepository; public BookController() { //通过工作单元来初始化仓储 bookRepository = unitOfWork.Repository<Book>(); } // GET: Book public ActionResult Index() { List<Book> listBooks= bookRepository.Table.ToList(); return View(listBooks); } public ActionResult CreateEditBook(int? id) { Book bookModel = new Book(); if (id.HasValue) { bookModel = bookRepository.GetById(id.Value); } return View(bookModel); } [HttpPost] public ActionResult CreateEditBook(Book model) { if (model.ID == 0) { model.ModifiedTime = DateTime.Now; model.AddedTime = DateTime.Now; model.IP = Request.UserHostAddress; bookRepository.Insert(model); } else { var editModel = bookRepository.GetById(model.ID); editModel.Title = model.Title; editModel.Author = model.Author; editModel.ISBN = model.ISBN; editModel.PublishedTime = model.PublishedTime; editModel.ModifiedTime = System.DateTime.Now; editModel.IP = Request.UserHostAddress; bookRepository.Update(editModel); } if (model.ID > 0) { return RedirectToAction("Index"); } return View(model); } public ActionResult DeleteBook(int id) { Book model= bookRepository.GetById(id); return View(model); } [HttpPost,ActionName("DeleteBook")] public ActionResult ConfirmDeleteBook(int id) { Book model= bookRepository.GetById(id); bookRepository.Delete(model); return RedirectToAction("Index"); } public ActionResult DetailBook(int id) { Book model= bookRepository.GetById(id); return View(model); } protected override void Dispose(bool disposing) { unitOfWork.Dispose(); base.Dispose(disposing); } }}
现在已经完成了控制器的方法，开始添加视图了：
CreateEdit：
@model MVC.Core.Data.Book@{ ViewBag.Title = "Create Edit Book";}<div class="book-example panel panel-primary"> <div class="panel-heading panel-head">Add / Edit Book</div> <div class="panel-body"> @using (Html.BeginForm()) { <div class="form-horizontal"> <div class="form-group"> @Html.LabelFor(model => model.Title, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.TextBoxFor(model => model.Title, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.ISBN, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.TextBoxFor(model => model.ISBN, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.Author, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.TextBoxFor(model => model.Author, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.PublishedTime, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.TextBoxFor(model => model.PublishedTime, new { @class = "form-control datepicker" }) </div> </div> <div class="form-group"> <div class="col-lg-8"></div> <div class="col-lg-3"> @Html.ActionLink("Back to List", "Index", null, new { @class = "btn btn-default" }) <button class="btn btn-success" id="btnSubmit" type="submit"> Submit </button> </div> </div> </div> } </div></div>@section scripts{ <script src="~/Scripts/bootstrap-datepicker.js" type="text/javascript"></script> <script src="~/Scripts/book-create-edit.js" type="text/javascript"></script>}
DeleteBook：
@model MVC.Core.Data.Book@{ ViewBag.Title = "Delete Book";}<div class="book-example panel panel-primary"> <div class="panel-heading panel-head">Delete Book</div> <div class="panel-body"> <h3>Are you sure you want to delete this?</h3> <h1>@ViewBag.ErrorMessage</h1> <div class="form-horizontal"> <div class="form-group"> @Html.LabelFor(model => model.Title, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.Title, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.Author, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.Author, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.ISBN, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.ISBN, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.PublishedTime, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.PublishedTime, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.AddedTime, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.AddedTime, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.ModifiedTime, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.ModifiedTime, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.IP, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.IP, new { @class = "form-control" }) </div> </div> @using (Html.BeginForm()) { <div class="form-group"> <div class="col-lg-1"></div> <div class="col-lg-9"> <input type="submit" value="Delete" class="btn btn-danger" /> @Html.ActionLink("Back to List", "Index", null, new { @class = "btn btn-success" }) </div> </div> } </div> </div></div>
DetailBook：
@model MVC.Core.Data.Book@{ ViewBag.Title = "Detail Book";}<div class="book-example panel panel-primary"> <div class="panel-heading panel-head">Book Detail</div> <div class="panel-body"> <div class="form-horizontal"> <div class="form-group"> @Html.LabelFor(model => model.Title, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.Title, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.Author, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.Author, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.ISBN, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.ISBN, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.PublishedTime, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.PublishedTime, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.AddedTime, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.AddedTime, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.ModifiedTime, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.ModifiedTime, new { @class = "form-control" }) </div> </div> <div class="form-group"> @Html.LabelFor(model => model.IP, new { @class = "col-lg-1 control-label" }) <div class="col-lg-9"> @Html.DisplayFor(model => model.IP, new { @class = "form-control" }) </div> </div> @using (Html.BeginForm()) { <div class="form-group"> <div class="col-lg-1"></div> <div class="col-lg-9"> @Html.ActionLink("Edit", "CreateEditBook", new { id = Model.ID }, new { @class = "btn btn-primary" }) @Html.ActionLink("Back to List", "Index", null, new { @class = "btn btn-success" }) </div> </div> } </div> </div></div>
Index：
@model IEnumerable<MVC.Core.Data.Book><div class="book-example panel panel-primary"> <div class="panel-heading panel-head">Books Listing</div> <div class="panel-body"> <a id="createEditBookModal" href="@Url.Action("CreateEditBook")" class="btn btn-success"> <span class="glyphicon glyphicon-plus"></span>Book </a> <table class="table" style="margin: 4px"> <tr> <th> @Html.DisplayNameFor(model => model.Title) </th> <th> @Html.DisplayNameFor(model => model.Author) </th> <th> @Html.DisplayNameFor(model => model.ISBN) </th> <th> Action </th> <th></th> </tr> @foreach (var item in Model) { <tr> <td> @Html.DisplayFor(modelItem => item.Title) </td> <td> @Html.DisplayFor(modelItem => item.Author) </td> <td> @Html.DisplayFor(modelItem => item.ISBN) </td> <td> @Html.ActionLink("Edit", "CreateEditBook", new { id = item.ID }, new { @class = "btn btn-success" }) | @Html.ActionLink("Details", "DetailBook", new { id = item.ID }, new { @class = "btn btn-primary" }) | @Html.ActionLink("Delete", "DeleteBook", new { id = item.ID }, new { @class = "btn btn-danger" }) </td> </tr> } </table> </div></div>
效果图：
- 4楼—阿辉
- autoFac是在VO--PO之间相互转换，，你这个仓储模式是在实体使用ef的CRUD的时候使用，，我感觉差别挺大的。【新手】
- 3楼—阿辉
- 这个和AutoFac有什么区别，，
- Re: 放飞梦想的翅膀
- @—阿辉，autofac是依赖倒置技术用到的容器。都差不多可以起到解耦合的作用，在我看来。
- 2楼井传红
- 用EF就能实现 到现在为止也不明白这样做的好处是什么。一直没明白大家热衷于用仓储的意义是什么?能不能告诉我什么情况下会考虑用仓储
- Re: 放飞梦想的翅膀
- @井传红，在我看来，用仓储是为了可扩展，
- Re: Ryan.Ruan
- @井传红，仓储为了降低业务逻辑层和数据访问层耦合度的
- 1楼nele
- 问下你这个UnitOfWork跟工厂有什么区别 感觉没有发挥UnitOfWork的作用，还是我不理解UnitOfWork，求指教。
- Re: fengzijun
- @nele，引用问下你这个UnitOfWork跟工厂有什么区别 感觉没有发挥UnitOfWork的作用，还是我不理解UnitOfWork，求指教。，，确实没有起到 UnitOfWork 的作用