Castle IOC容器实践之TypedFactory Facility（二）
2006-05-23 08:56:00
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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。 本文出自 “TerryLee技术专栏” 博客，请务必保留此出处http://terrylee.blog.51cto.com/342737/67689 本文出自 51CTO.COM技术博客 |
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