TinyFrame续篇：整合Spring IOC实现依赖注入

上一篇主要讲解了如何搭建基于CodeFirst的ORM，并且在章节末我们获取了上下文对象的实例：BookContext。这节主要承接上一篇，来讲解如何整合Spring IOC容器实现控制反转，依赖注入功能。

首先，我们来定义一个接口IBookRepository，用于描述所有的元数据操作集合，所谓元数据操作集合，是指不含有任何业务逻辑的操作集合，只是针对单表操作：

   1:  public interface IBookRepository

   2:      {

   3:          IQueryable<Book> GetAllBooks();

   4:          Book GetBook(int bookID);

   5:          bool InsertBook(Book book);

   6:          bool UpdateBook(Book originalBook, Book updatedBook);

   7:          bool DeleteBook(int id);

   8:          //==============================

   9:          IQueryable<BookLend> GetAllBookLends();

  10:          BookLend GetBookLend(int bookLendID);

  11:          bool InsertBookLend(BookLend bookLend);

  12:          bool UpdateBookLend(BookLend originalBookLend, BookLend updatedBookLend);

  13:          bool DeleteBookLend(int id);

  14:          //==============================

  15:          IQueryable<BookType> GetAllBookTypes();

  16:          BookType GetBookType(int bookTypeID);

  17:          bool InsertBookType(BookType bookType);

  18:          bool UpdateBookType(BookType originalBookType, BookType updatedBookType);

  19:          bool DeleteBookType(int id);

  20:          //==============================

  21:          IQueryable<BookPlace> GetAllBookPlaces();

  22:          BookPlace GetBookPlace(int bookPlaceID);

  23:          bool InsertBookPlace(BookPlace bookPlace);

  24:          bool UpdateBookPlace(BookPlace originalBookPlace, BookPlace updatedBookPlace);

  25:          bool DeleteBookPlace(int id);

  26:          //============================== 

  27:          IQueryable<Student> GetAllStudents();

  28:          Student GetStudent(int studentID);

  29:          bool InsertStudent(Student student);

  30:          bool UpdateStudent(Student originalStudent, Student updatedStudent);

  31:          bool DeleteStudent(int id);

  32:   

  33:          //=====================================

  34:          IQueryable<Student> GetStudentsByBookLend(int bookLendID);

  35:          IQueryable<Book> GetBooksByBookLend(int bookLendID);

  36:          IQueryable<Book> GetBookByType(int bookTypeID);

  37:          IQueryable<Book> GetBookByPlace(int bookPlaceID);

  38:      }

然后新建一个BookRepository类，用于提供其实现，由于这里篇幅有限，我就只实现GetAllBooks方法和GetBook(int bookID)方法：

   1:   public class BookRepository:IBookRepository

   2:      {

   3:          public BookRepository()

   4:          {

   5:              this.context = new BookContext();

   6:          }

   7:   

   8:          private BookContext context;

   9:   

  10:          public IQueryable<Book> GetAllBooks()

  11:          {

  12:              return context.Books.AsQueryable();

  13:          }

  14:   

  15:          public Book GetBook(int bookID)

  16:          {

  17:              return context.Books.Where(c => c.ID == bookID).FirstOrDefault();

  18:          }

  19:   

  20:          //comment here...

  21:      }

建立好以后，我们新建一个基于WCF REST Service Application模板的Web项目项目，并命名为BookStore.RestService，用来消费刚刚创建的操作：

当这个项目创建好以后，我们首先需要添加对Spring的引用：

Common.Logging.dll

Spring.Aop.dll

Spring.Core.dll

然后新建一个ServiceBase类，用于初始化IOC容器：

   1:  using System;

   2:  using System.Collections.Generic;

   3:  using System.Linq;

   4:  using System.Web;

   5:  using Spring.Context.Support;

   6:  using Spring.Context;

   7:   

   8:  namespace BookStore.RestService

   9:  {

  10:      public class ServiceBase

  11:      {

  12:          public ServiceBase()

  13:          {

  14:              applicationContext = ContextRegistry.GetContext();

  15:          }

  16:          protected IApplicationContext applicationContext = null;

  17:      }

  18:  }

创建完毕后，新建一个BookService类，继承自ServiceBase类：

   1:  namespace BookStore.RestService

   2:  {

   3:      [ServiceContract]

   4:      [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]

   5:      [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)]

   6:      public class BookService:ServiceBase

   7:      {

   8:          public BookService()

   9:              : base()

  10:          {

　　　　　　　　　　bookRepository = (IBookRepository)applicationContext["BookRepository"];

  12:          }

  13:   

  14:          private IBookRepository bookRepository;

  15:   

  16:          [WebInvoke(

  17:              Method = "GET",

  18:              ResponseFormat = WebMessageFormat.Xml,

  19:              BodyStyle = WebMessageBodyStyle.Bare,

  20:              UriTemplate = "/GetAllBooks/")]

  21:          public List<Book> GetAllBooks()

  22:          {

  23:              return bookRepository.GetAllBooks().ToList();

  24:          }

  25:   

  26:           [WebInvoke(

  27:              Method = "GET",

  28:              ResponseFormat = WebMessageFormat.Xml,

  29:              BodyStyle = WebMessageBodyStyle.Bare,

  30:              UriTemplate = "/GetBookByID/?id={id}")]

  31:          public Book GetBookByID(int id)

  32:          {

  33:              return bookRepository.GetBook(id);

  34:          }

  35:      }

  36:  }

大家可以参看我之前的文章来了解如何创建基于WCF 的Restful Service，这里我就不细讲了。

需要注意的是，首先我们初始化了一个IBookRepository 接口，然后在其构造函数中，我们从Spring容器中去拿继承自IBookRepository接口的操作实例。其中，applicationContext["BookRepository"]代码段表明我们是要去web.config配置文件中去取BookRepository的节点声明。下面是配置节点部分：

首先是configSections节点声明，用于引入Spring类库配置：

   1:    <configSections>

   2:      <sectionGroup name="spring">

   3:        <section name="context" type="Spring.Context.Support.ContextHandler, Spring.Core"/>

   4:        <section name="objects" type="Spring.Context.Support.DefaultSectionHandler, Spring.Core"/>

   5:      </sectionGroup>

其次是<spring>节点，用于容器配置：

   1:   <spring>

   2:      <context>

   3:        <resource uri="config://spring/objects"/>

   4:      </context>

   5:   

   6:      <objects xmlns="http://www.springframework.net">

   7:        <object name="BookRepository" type="BookStore.Data.BookRepository, BookStore.Data" singleton="false"/>

   8:      </objects>

   9:    </spring>

由于配置比较简单，我这里就不多说了。这样进行依赖注入后的好处就是，当以后业务需求变更，无论是增加新的功能，还是更换现有的功能，无需将整个项目编译，只需要将更改的部分编译过，然后将dll在配置文件中指定一下，就可以轻松实现业务追加或者更新了，非常便于维护。

配置完成后，当我们运行之后，就可以看到正确的浏览效果了：

这节就到这里，下节准备讲解如何实现日志拦截和用户认证拦截。