Castle IOC容器实践之FactorySupport Facility-阿里云开发者社区

摘要：FactorySupport Facility允许我们使用已经存在的工厂来创建组件的实例，可以把已经存在的对象模型加入到容器中，以便它能够使用自动装配。它使用了以下两种处理策略：

1 ．使用访问器来访问组件的实例

2 ．使用静态方法或者实例方式来访问组件的实例

主要内容

1 ．概述

2 ．为什么需要FactorySupport Facility

3 ．如何使用

4 ．常见的配置示例

5 ．实现原理浅析

一．概述

FactorySupport Facility 允许我们使用已经存在的工厂来创建组件的实例，可以把已经存在的对象模型加入到容器中，以便它能够使用自动装配。它使用了以下两种处理策略：

1 ．通过访问器来访问组件的实例

2 ．通过静态方法或者实例方式来访问组件的实例

二．为什么需要FactorySupport Facility

为了回答这个问题，我们先来看一个简单的使用工厂的例子，如下代码所示：

public interface IComponent

{

void Display();

}

public class MyComponent : IComponent

{

public MyComponent()

{

}

public void Display()

{

Console.WriteLine("MyComponent

");

}

public class MyFactory

{

public MyFactory()

{

}

public IComponent Create()

{

return new MyComponent();

}

现在要在程序中使用 MyComponent的实例，简单一点会这样去写：

public class App

{

static void Main()

{

MyFactory factory = new MyFactory();

IComponent comp = factory.Create();

comp.Display();

}

正如你所看到的，在程序中使用 new关键字创建了一个工厂的实例，再由工厂得到组件的实例。现在我们看使用 FactorySupport Facility后带来了什么好处。工厂和组件的代码不变，仍然是：

public interface IComponent

{

void Display();

}

public class MyComponent : IComponent

{

public MyComponent()

{

}

public void Display()

{

Console.WriteLine("MyComponent

");

}

public class MyFactory

{

public MyFactory()

{

}

public IComponent Create()

{

return new MyComponent();

}

配置文件，现在你可以不用理解怎么去配置，后面会讲到。

<? xml version="1.0" encoding="utf-8" ?>

< configuration >

< facilities >

< facility id ="factorysupport" type ="Castle.Facilities.FactorySupport.FactorySupportFacility, Castle.MicroKernel" />

</ facilities >

< components >

< component id ="myfactory" type ="FactorySupportDemo.MyFactory,FactorySupportDemo" />

< component id ="mycomp" type ="FactorySupportDemo.MyComponent,FactorySupportDemo"

factoryId ="myfactory" factoryCreate ="Create" ></ component >

</ components >

</ configuration >

使用组件的实例

public class App

{

static void Main()

{

IWindsorContainer container = new WindsorContainer("../../Basic.xml");

IComponent instance = (IComponent) container["mycomp"];

instance.Display();

}

看到了吗？我们并没有使用 new关键字创建任何对象，只是把工厂、组件等通过配置文件抛给了 IOC容器，再从容器中往外取的时候，就可以直接取到组件的实例，这些实例是由工厂自动创建的，这正是 FactorySupport Facility的作用。

三．如何使用

知道了为什么需要FactorySupport Facility之后，下面就来看如何使用Facility。在前面的代码中大家都已经看到了，使用FactorySupport Facility是非常的简单。

1 ．加入FactorySupport Facility到容器中，可以使用代码加入也可以使用配置文件。

使用代码加入：

IWindsorContainer container = new WindsorContainer( " ../../Basic.xml " );

container.AddFacility( " factorysupport " , new Castle.Facilities.FactorySupport.FactorySupportFacility());

使用配置文件：

< facilities >

< facility id ="factorysupport" type ="Castle.Facilities.FactorySupport.FactorySupportFacility, Castle.MicroKernel" />

</ facilities >

2 ．加入组件时指定使用的是哪种方式

如果使用访问器只需要指定访问器的名称就可以了：

< component id ="accessor.comp"

type ="Castle.Facilities.FactorySupport.Tests.Components.SingletonWithAccessor, Castle.Facilities.FactorySupport.Tests"

instance-accessor ="Instance" >

</ component >

如果使用工厂方法，需要指定工厂 ID和工厂方法：

< component id ="mycomp"

type ="Castle.Facilities.FactorySupport.Tests.Components.MyComp, Castle.Facilities.FactorySupport.Tests"

factoryId ="mycompfactory" factoryCreate ="Create" >

</ component >

四．常见的配置示例

这是一些常见的配置示例，来自于Castle自带的测试代码中。

1 ．访问器配置示例

有这样一个单件类

public class SingletonWithAccessor

{

private static readonly SingletonWithAccessor instance = new SingletonWithAccessor();

private SingletonWithAccessor()

{

}

public static SingletonWithAccessor Instance

{

get { return instance; }

}

配置文件如下：

<? xml version="1.0" encoding="utf-8" ?>

< configuration >

< facilities >

< facility id ="factorysupport" type ="Castle.Facilities.FactorySupport.FactorySupportFacility, Castle.MicroKernel" />

</ facilities >

< components >

< component id ="accessor.comp" type ="Castle.Facilities.FactorySupport.Tests.Components.SingletonWithAccessor, Castle.Facilities.FactorySupport.Tests"

instance-accessor ="Instance" ></ component >

</ components >

</ configuration >

2 ．普通工厂配置示例

组件类和工厂类如下

public class MyComp

{

public MyComp()

{

}

public class MyCompFactory

{

public MyComp Create()

{

return new MyComp();

}

配置文件如下：

<? xml version="1.0" encoding="utf-8" ?>

< configuration >

< facilities >

< facility id ="factorysupport" type ="Castle.Facilities.FactorySupport.FactorySupportFacility, Castle.MicroKernel" />

</ facilities >

< components >

< component id ="mycompfactory" type ="Castle.Facilities.FactorySupport.Tests.Components.MyCompFactory, Castle.Facilities.FactorySupport.Tests" />

< component id ="mycomp" type ="Castle.Facilities.FactorySupport.Tests.Components.MyComp, Castle.Facilities.FactorySupport.Tests"

factoryId ="mycompfactory" factoryCreate ="Create" ></ component >

</ components >

</ configuration >

3 ．带参工厂配置示例

组件类和工厂类如下：

public class MyComp

{

private string storeName;

private IDictionary props;

internal MyComp()

{

}

internal MyComp(String storeName, IDictionary props)

{

this.storeName = storeName;

this.props = props;

}

public string StoreName

{

get { return storeName; }

}

public IDictionary Props

{

get { return props; }

}

public class MyCompFactory2

{

public MyCompFactory2()

{

}

public MyComp Create(String storeName, IDictionary props)

{

return new MyComp(storeName, props);

}

配置文件如下：

<? xml version="1.0" encoding="utf-8" ?>

< configuration >

< facilities >

< facility id ="factorysupport" type ="Castle.Facilities.FactorySupport.FactorySupportFacility, Castle.MicroKernel" />

</ facilities >

< components >

< component id ="mycompfactory" type ="Castle.Facilities.FactorySupport.Tests.Components.MyCompFactory2, Castle.Facilities.FactorySupport.Tests" ></ component >

< component id ="mycomp" type ="Castle.Facilities.FactorySupport.Tests.Components.MyComp, Castle.Facilities.FactorySupport.Tests"

factoryId ="mycompfactory" factoryCreate ="Create" >

< parameters >

< storeName > MyStore </ storeName >

< props >

< dictionary >

< entry key ="key1" > item1 </ entry >

< entry key ="key2" > item2 </ entry >

</ dictionary >

</ props >

</ parameters >

</ component >

</ components >

</ configuration >

4 ．使用自动装配工厂配置示例

组件类和工厂类如下：

public interface IMyService

{

}

public class MyComp

{

private IMyService serv;

internal MyComp()

{

}

internal MyComp(IMyService serv)

{

this.serv = serv;

}

public IMyService Service

{

get { return serv; }

}

public class MyCompFactory3

{

public MyCompFactory3()

{

}

public MyComp Create(IMyService serv)

{

return new MyComp(serv);

}

配置文件如下：

<? xml version="1.0" encoding="utf-8" ?>

< configuration >

< facilities >

< facility id ="factorysupport" type ="Castle.Facilities.FactorySupport.FactorySupportFacility, Castle.MicroKernel" />

</ facilities >

< components >

< component id ="myserv" service ="Castle.Facilities.FactorySupport.Tests.Components.IMyService, Castle.Facilities.FactorySupport.Tests"

type ="Castle.Facilities.FactorySupport.Tests.Components.DefaultMyService, Castle.Facilities.FactorySupport.Tests" />

< component id ="mycompfactory" type ="Castle.Facilities.FactorySupport.Tests.Components.MyCompFactory3, Castle.Facilities.FactorySupport.Tests" ></ component >

< component id ="mycomp" type ="Castle.Facilities.FactorySupport.Tests.Components.MyComp, Castle.Facilities.FactorySupport.Tests"

factoryId ="mycompfactory" factoryCreate ="Create" >

</ component >

</ components >

</ configuration >

五．实现原理浅析

FactorySupport Facility 的实现也是非常的简单，主要是通过两个 ComponentActivator 来实现，分别为AccessorActivator和FactoryActivator，根据配置文件的不同调用不同的Activator。

String instanceAccessor = model.Configuration.Attributes[ " instance-accessor " ];

String factoryId = model.Configuration.Attributes[ " factoryId " ];

String factoryCreate = model.Configuration.Attributes[ " factoryCreate " ];

if (instanceAccessor != null )

{

model.ExtendedProperties.Add( "instance.accessor", instanceAccessor );

model.CustomComponentActivator = typeof(AccessorActivator);

}

else if (factoryId != null )

{

model.ExtendedProperties.Add( "factoryId", factoryId );

model.ExtendedProperties.Add( "factoryCreate", factoryCreate );

model.CustomComponentActivator = typeof(FactoryActivator);

}

好了，关于 FactorySupport Facility就介绍到这儿，更多 Castle的文章您可以访问《 Castle 开发系列文章》。

PDF版本下载：/Files/Terrylee/FactorySupportFacility.rar

示例代码下载：/Files/Terrylee/FactorySupportDemo.rar

本文转自lihuijun51CTO博客，原文链接： http://blog.51cto.com/terrylee/67692 ，如需转载请自行联系原作者

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