如何配置HK2注入通过工厂方法创建的对象? [英] How do I configure HK2 to inject an object created by a factory method?

问题描述

在HK2中，用于配置注入的基本示例代码如下(在扩展AbstractBinder的类中:

In HK2 the basic example code for configuring injection is this (within a class that extends AbstractBinder:

bind(BuilderHelper
    .link(FooImpl.class)    // the class of the object to be injected
    .to(FooInterface.class) // identifies what @Inject fields to link to
    .build());

这会导致HK2在需要创建FooInterface时调用构造函数FooImpl().

This causes HK2 to call the constructor FooImpl() when it needs to create a FooInterface.

如果FooImpl没有构造函数怎么办?

What if FooImpl doesn't have a constructor?

• 如果要使用静态工厂方法实例化FooImpl.getInstance()
，该怎么办
• 如果打算由工厂对象实例化fooFactory.create()
，该怎么办

• What if it's intended to be instantiated with a static factory method FooImpl.getInstance()
• What if it's intented to be instantiated by a factory object fooFactory.create()

我看到ResourceConfig具有方法bind(FactoryDescriptors factoryDescriptors)，但是我不清楚用于构建FactoryDescriptors对象的惯用法是什么，并且无法在线找到任何示例.

I see that ResourceConfig has a method bind(FactoryDescriptors factoryDescriptors) but it is not clear to me what the idiom is for building a FactoryDescriptors object, and have not been able to find any examples online.

推荐答案

虽然我仍然看不到使用BuilderHelper EDSL进行操作的方法(对于一般情况，这似乎也太过苛刻了)，但可以使用以下方法:

While I still can't see a way to do it using the BuilderHelper EDSL (it appears this is overkill for the common case too), the following works:

  bindFactory(FooFactory.class)
       .to(FooInterface.class);

这要求FooFactory是Factory<FooInterface>的实现，因此您需要围绕现有的任何工厂都有外观.我在需要它的时候作为私人内部类来做.

This requires that FooFactory is an implementation of Factory<FooInterface>, so you need a facade around any existing factory you have. I did it as a private inner class where I needed it.

 private static class FooFactory implements Factory<FooInterface> {

    @Override
    public void dispose(FooInterface foo) {
      // meh
    }

    @Override
    public FooInterface provide() {
      return SomeFactory.getInstance();
    }
 }

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