摘要：在Castle IOC容器实践之TypedFactory Facility（一）里面大家都已经知道了如何去使用TypedFactory Facility，也已经体会到它的方便之处了，为了更好的使用它，本篇我们对TypedFactory Facility的原理做一些简单的分析。
主要内容
TypedFactory Facility
原理分析
……
在TypedFactory Facility中，有一个
FactoryEntry
类，这个类与我们平时项目开发中的实体类有一些类似，它用来记录工厂的相关信息，包括工厂的ID，工厂的接口，创建方法和销毁方法。这个类实现如下：
public
class
FactoryEntry
{
private String _id; private Type _factoryInterface; private String _creationMethod; private String _destructionMethod; public FactoryEntry(String id, Type factoryInterface, String creationMethod, String destructionMethod)
{ // 
省略了验证及异常处理 _id = id; _factoryInterface = factoryInterface; _creationMethod = creationMethod; _destructionMethod = destructionMethod;
} public String Id { get { return _id; } } public Type FactoryInterface { get { return _factoryInterface; } } public String CreationMethod { get { return _creationMethod; } } public String DestructionMethod { get { return _destructionMethod; } }
}
TypedFactoryFacility
同样是继承于AbstractFacility，关于Facility的继承关系我在前面的文章中已经说过了。TypedFactory Facility在初始化的时候首先会获取工厂的类型，通过SubSystem来得到：
protected
override
void
Init()
{ Kernel.AddComponent( "typed.fac.interceptor", typeof(FactoryInterceptor) ); ITypeConverter converter = (ITypeConverter) Kernel.GetSubSystem( SubSystemConstants.ConversionManagerKey ); AddFactories(FacilityConfig, converter);}
protected
virtual
void
AddFactories(IConfiguration facilityConfig, ITypeConverter converter)
{ if (facilityConfig != null) { foreach(IConfiguration config in facilityConfig.Children["factories"].Children) { String id = config.Attributes["id"]; String creation = config.Attributes["creation"]; String destruction = config.Attributes["destruction"]; Type factoryType = (Type) converter.PerformConversion( config.Attributes["interface"], typeof(Type) ); try { AddTypedFactoryEntry( new FactoryEntry(id, factoryType, creation, destruction) ); } catch(Exception ex) { throw new ConfigurationException("Invalid factory entry in configuration", ex); } } }}
然后再创建一个
FactoryEntry实例，记录了工厂的信息，放在了
ComponentModel的扩展属性
ExtendedProperties中，设置
ComponentModel的生命周期为
Singleton：
public
void
AddTypedFactoryEntry( FactoryEntry entry )
{ ComponentModel model = new ComponentModel(entry.Id, entry.FactoryInterface, typeof(Empty)); model.LifestyleType = LifestyleType.Singleton; model.ExtendedProperties["typed.fac.entry"] = entry; model.Interceptors.Add( new InterceptorReference( typeof(FactoryInterceptor) ) ); Kernel.AddCustomComponent( model );}
在容器中加入一个工厂接口的拦截器
FactoryInterceptor
，当从容器中获取工厂时，会被拦截器拦截，拦截器的实现如下：
[Transient]
public
class
FactoryInterceptor : IMethodInterceptor, IOnBehalfAware
{ private FactoryEntry _entry; private IKernel _kernel; public FactoryInterceptor(IKernel kernel) { _kernel = kernel; } public void SetInterceptedComponentModel(ComponentModel target) { _entry = (FactoryEntry) target.ExtendedProperties["typed.fac.entry"]; } public object Intercept(IMethodInvocation invocation, params object[] args) { String name = invocation.Method.Name; if (name.Equals(_entry.CreationMethod)) { if (args.Length == 0 || args[0] == null) { return _kernel[ invocation.Method.ReturnType ]; } else { return _kernel[ (String) args[0] ]; } } else if (name.Equals(_entry.DestructionMethod)) { if (args.Length == 1) { _kernel.ReleaseComponent( args[0] ); return null; } } return invocation.Proceed(args); }}
还有一点需要我们注意的是在上面实例化
ComponentModel的时候用到了一个
Empty类，这个类是一个空类，没有任何实现：
public
class
Empty
{ }
在实例化
ComponentModel时需要传入的几个参数是：
public
ComponentModel(String name, Type service, Type implementation)
{ this.name = name; this.service = service; this.implementation = implementation; this.lifestyleType = LifestyleType.Undefined;}
即这里用一个空的类型来代替实现了的类型。
本文转自lihuijun51CTO博客，原文链接：http://blog.51cto.com/terrylee/67689
，如需转载请自行联系原作者
