上一讲介绍了DDD中的领域层，并提到下次要讲Unity，所以这篇文章当然就要介绍它了，呵呵，Unity是Microsoft.Practices中的一部分，主要实现了依赖注入的功能，或者叫它控制反转，对于控制反转(IoC)的文章我介绍了不少，Autofac,Castle等等，今天主要说一下Unity！
在我的ＤＤＤ架构项目中，各层间实现IoC使用的是Unity，因为考虑到AOP,cache等功能，所以就直接用Microsoft.Practices组件了，它真的很强大！这次的项目在业务上采用ＷＣＦ实现，所以ＷＣＦ业务与基础设施之间会有通信，而基础设施只是去实现Domain定义的功能，所以这两个层之间也会有通信，最后就是Domain与ＷＣＦ之间同样存在着接口的通信，如图：
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Domain层定义一个接口，部分代码如下：
/// <summary>
/// 获取产品列表
/// </summary>
/// <returns></returns>
IQueryable<Product> GetProduct();
基础设施层实现它
public IQueryable<Product> GetProduct()
{
return this.GetModel();
}
它们之间的通信不存在IoC，因为如果你要使用其它的持久化方法，可以再建立一个项目，以别一种方式去实现持久化
WCF去声明一个Domain层的接口，实例化它的基础设施层的实例，这个过程需要解耦合，我们使用Unity来实现，它需要我们在config中去定义如何去实例化。
public class ProductServiceImpl : IProductService
{
private readonly IProductRepository _productRepository; /// <summary>
/// 构造方法注入
/// </summary>
/// <param name="productRepository"></param>
public ProductServiceImpl(IProductRepository productRepository)
{
if (productRepository == (IProductRepository)null)
throw new ArgumentException("context can't is null.");
_productRepository = productRepository;
} #region IProductService 成员
public ProductDTO GetProductByID(int id)
{
Mapper.CreateMap<Product, ProductDTO>();
return Mapper.Map<Product, ProductDTO>(_productRepository.Find(id));
}
}
上面使用unity中的构造方法注入，我们还可以使用服务调度器进行注入，看这种代码
public class ProductService : ServiceBase, IProductService
{ //通过ServiceLocator从IoC容器中获得对象
IProductService _productService = ServiceLocator.Instance.GetService<IProductService>();
#region IProductService 成员 public ProductDTO GetProductByID(int id)
{
return _productService.GetProductByID(id);
} }
下面是配置文件中需要注入的代码片断，包括缓存模块和日志模块
<configSections>
<!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
<section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection, Microsoft.Practices.Unity.Configuration" />
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
<section name="cachingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Caching.Configuration.CacheManagerSettings, Microsoft.Practices.EnterpriseLibrary.Caching, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
</configSections>
<!--BEGIN: Unity-->
<unity xmlns="http://schemas.microsoft.com/practices/2010/unity">
<sectionExtension type="Microsoft.Practices.Unity.InterceptionExtension.Configuration.InterceptionConfigurationExtension, Microsoft.Practices.Unity.Interception.Configuration" />
<container>
<extension type="Interception" />
<register type="Project.Caching.ICacheProvider, Project.Caching" mapTo="Project.Caching.EntLibCacheProvider, Project.Caching" />
<!--对数据上下文的注入-->
<register type="DDD_AOP_WCF.Domain.Products.IProductRepository, DDD_AOP_WCF.Domain" mapTo="DDD_AOP_WCF.Infrastructure.Repository.ProductRepository, DDD_AOP_WCF.Infrastructure" />
<!--对WCF的访问进行的注入与缓存和异常的拦截-->
<register type="DDD_AOP_WCF.ServiceContracts.IProductService, DDD_AOP_WCF.ServiceContracts" mapTo="DDD_AOP_WCF.Service.Implements.ProductServiceImpl, DDD_AOP_WCF.Service">
<!-- <interceptor type="VirtualMethodInterceptor" />-->
<interceptor type="InterfaceInterceptor" />
<interceptionBehavior type="Project.InterceptionBehaviors.CachingBehavior, Project.InterceptionBehaviors" />
<interceptionBehavior type="Project.InterceptionBehaviors.ExceptionLoggingBehavior, Project.InterceptionBehaviors" />
</register>
</container>
</unity>
<!--END: Unity-->
<!--BEGIN: Caching-->
<cachingConfiguration defaultCacheManager="ByteartRetailCacheManager">
<cacheManagers>
<add name="ByteartRetailCacheManager" type="Microsoft.Practices.EnterpriseLibrary.Caching.CacheManager, Microsoft.Practices.EnterpriseLibrary.Caching, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" expirationPollFrequencyInSeconds="" maximumElementsInCacheBeforeScavenging="" numberToRemoveWhenScavenging="" backingStoreName="NullBackingStore" />
</cacheManagers>
<backingStores>
<add type="Microsoft.Practices.EnterpriseLibrary.Caching.BackingStoreImplementations.NullBackingStore, Microsoft.Practices.EnterpriseLibrary.Caching, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" name="NullBackingStore" />
</backingStores>
</cachingConfiguration>
<!--END: Caching-->
<!--BEGIN: log4net-->
<log4net>
<appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="log.log"/>
<appendToFile value="true"/>
<rollingStyle value="Size"/>
<maxSizeRollBackups value="10"/>
<maximumFileSize value="100KB"/>
<staticLogFileName value="true"/>
<layout type="log4net.Layout.PatternLayout">
<param name="ConversionPattern" value="%newline%date [%thread] %-5level %logger - %message%newline"/>
</layout>
</appender>
<logger name="ByteartRetail.Logger" >
<!--control log level: ALL|DEBUG|INFO|WARN|ERROR|FATAL|OFF-->
<!--如果没有定义LEVEL的值，则缺省为DEBUG-->
<level value="INFO"/>
<appender-ref ref="RollingFileAppender"/>
</logger>
</log4net>
<!--END: log4net-->
好了，对于Unity在DDD中的使用就介绍到这里，如有不清楚的地方，可以直接给我留言或发email!