Spring：如何获取bean层次结构？

Question

Is it possible to get the beans in which a bean was injected(Via Spring Framework)? And if yes how?

Thanks! Patrick

Answer 1

如果您正在寻找合作bean，您可以尝试实现BeanFactoryAware

Answer 2

只是为了扩展David的答案 - 一旦实现了BeanFactoryAware，就会得到BeanFactory的引用，你可以通过BeanFactory.ContainsBean（String beanName）来查询bean工厂中是否存在特定bean 。

Answer 3

Here's a BeanFactoryPostProcessor sample implementation that may help you here:

class CollaboratorsFinder implements BeanFactoryPostProcessor {

    private final Object bean;
    private final Set<String> collaborators = new HashSet<String>();

    CollaboratorsFinder(Object bean) {
        if (bean == null) {
            throw new IllegalArgumentException("Must pass a non-null bean");
        }
        this.bean = bean;
    }

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {

        for (String beanName : BeanFactoryUtils.beanNamesIncludingAncestors(beanFactory)) {
            BeanDefinition beanDefinition = beanFactory.getBeanDefinition(beanName);
            if (beanDefinition.isAbstract()) {
                continue;   // assuming you're not interested in abstract beans
            }
            // if you know that your bean will only be injected via some setMyBean setter:
            MutablePropertyValues values = beanDefinition.getPropertyValues();
            PropertyValue myBeanValue = values.getPropertyValue("myBean");
            if (myBeanValue == null) {
                continue;
            }
            if (bean == myBeanValue.getValue()) {
                collaborators.add(beanName);
            }
            // if you're not sure the same property name will be used, you need to
            // iterate through the .getPropertyValues and look for the one you're
            // interested in.

            // you can also check the constructor arguments passed:
            ConstructorArgumentValues constructorArgs = beanDefinition.getConstructorArgumentValues();
            // ... check what has been passed here 

        }

    }

    public Set<String> getCollaborators() {
        return collaborators;
    }
}

Of course, there's a lot more to it (if you want to also catch proxies of your original bean or whatever). And, of course, the above code is completely untested.

EDIT: To make use of this, you need to declare it as a bean in your application context. As you already noticed, it requires your bean (the one you want to monitor) to be injected into it (as a constructor-arg).

As your question refers to the "bean hiearchy", I edited to look for the bean names in the entire hierarcy ...IncludingAncestors . Also, I assumed your bean is a singleton and that it is possible to inject it into the postprocessor (although in theory the postProcessor should be initialized before other beans -- need to see if this actually works).