Castle IOC容器实践之TypedFactory Facility（二）-白红宇

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