温莎城堡：如何防止工厂创建的对象中的圆形引用被创建的对象返回工厂 [英] Castle Windsor: How to prevent circular references in factory-created objects were the created objects refers back to the factory

问题描述

我正在使用温莎城堡作为我的IoC容器，但遇到了一些问题。最好用代码解释一下，因此我将尝试一下。
我有一个工厂类，应该为我提供某些接口的实现：

I am using windsor castle as my IoC container, and has run in to a bit of a problem. This is best explained in code, so I´ll give it a try. I have a factory class, that should provide me with implementations of a certain interface:

public interface IObjectCreatorFactory
{
    IObjectCreator GetObjectCreator(Type objectType);
}
public interface IObjectCreator
{
    T CreateObject<T>(IDataRow data);
    bool SupportsType(Type type);
}

工厂类的实现可能看起来像这样，尽管我不确定是这样的方式：
公共接口ObjectCreatorFactory：IObjectCreatorFactory
{
IEnumerable specificCreators;
IObjectCreator defaultCreator;

Implementation of the factory class could look like this, though I am not sure this is the way to go: public interface ObjectCreatorFactory:IObjectCreatorFactory { IEnumerable specificCreators; IObjectCreator defaultCreator;

    public ObjectCreatorFactory(IEnumerable<IObjectCreator> specificCreators, IObjectCreator defaultCreator)
    {
        this.specificCreators= specificCreators;
        this.defaultCreator= defaultCreator;
    }
    public IObjectCreator GetObjectCreator(Type objectType)
    {
        foreach (IObjectCreator creator in specificCreators)
        {
            if (creator.SupportsType(objectType))
            {
                return creator;
            }
        }
        return defaultCreator;
    }
}

现在这行得通，但是如果我想要我的IObjectCreator实例使用特定的IObjectCreator创建子对象，我想调用ObjectCreatorFactory，这显然导致循环引用：

Now this would work out ok, but if I want my IObjectCreator instance to create child objects using a specific IObjectCreator, i would like to call ObjectCreatorFactory, and this obviously results in a circular reference:

public void SpecificObjectCreator:IObjectCreator
{
    IObjectCreatorFactory objCreatorFactory;
    public SpecificObjectCreator(IObjectCreatorFactory objCreatorFactory)
    {
        this.objCreatorFactory = objCreatorFactory;
    }
    T CreateObject<T>(IDataRow data)
    {
        T obj = new T;
        ChildObject childObject = objCreatorFactory.GetObjectCreator(typeof(ChildObject)).CreateObject<ChildObject>(data);
         .......
    }
    bool SupportsType(Type type);        
}

这不可行。

推荐答案

我只是将工厂从各种特定对象创建者的构造函数中移出，并在IObjectCreator接口上引入一种方法，负责初始化创建者：

I would simply move the factory out of the constructors of the various specific object creators, and introduce a method on the IObjectCreator interface instead, responsible for initialising the creators:

public interface IObjectCreator
{
    T CreateObject<T>(IDataRow data);
    bool SupportsType(Type type);
    void Initialize(IObjectCreatorFactory factory);
}

然后在传递给工厂的每个对象创建者上调用Initialze（this）

And then just invoke Initialze(this) on each object creator passed into the factory.

过去，我使用自定义生命周期阶段来自动调用组件的构造后设置，以避免循环依赖并采取照顾其他相关问题（例如，从外部资源（如数据库）中应用其他组件配置）-但这可能对于您所需的功能而言过于矫kill过正。

In the past I've used custom life cycle stages to take care of automatically invoking "post-construction" setup of components to both avoid circular dependencies and also to take care of other associated concerns (i.e. applying additional component configuration from an external source like a database) - but it's probably overkill for what you need.

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