Spring Boot自动配置命令 [英] Spring Boot auto-configuration order

问题描述

我想创建一个Spring Boot自动配置类，它（有条件地）创建一个bean A 。但挑战是，必须在另一个bean B 之前创建一个Spring Boot的默认自动配置类。 bean B 不依赖于 A 。

I want to create a Spring Boot auto-configuration class that (conditionally) creates a single bean A. The challenge however is, that this been has to be created before another bean B is created in one of Spring Boot's default auto-configuration classes. The bean B does not depend on A.

我的第一次尝试是使用 @AutoConfigureBefore 。这不符合我的预期和判断，来自Dave Syer的此评论不应该。

My first try was to use @AutoConfigureBefore. That didn't work the way I expected and judging from this comment by Dave Syer it shouldn't.

一些背景：前面提到的bean A 改变一个Mongo数据库，这必须在 MongoTemplate 已创建。

Some background: The aforementioned bean A alters a Mongo Database and this has to happen before MongoTemplate is created.

推荐答案

事实证明，我想要的是动态地使 B 的实例依赖于 A 。这可以通过使用 BeanFactoryPostProcessor 来实现改变 B bean的bean定义。

It turns out, what I want is to dynamically make instances of B depend on A. This can be achieved by using a BeanFactoryPostProcessor to alter the bean definitions of B beans.

public class DependsOnPostProcessor implements BeanFactoryPostProcessor {

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        String[] beanNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
                beanFactory, B.class, true, false);
        for (String beanName : beanNames) {
            BeanDefinition definition = beanFactory.getBeanDefinition(beanName);
            definition.setDependsOn(StringUtils.addStringToArray(
                    definition.getDependsOn(), "beanNameOfB");
        }
    }

}

这适用于普通的Spring，不需要Spring Boot。要完成自动配置，我需要添加bean定义 DependsOnPostProcessor 到实例化bean的配置类 A 。

This works with plain Spring, no Spring Boot required. To complete the auto-configuration I need to add the bean definition for the DependsOnPostProcessor to the configuration class that instantiates the bean A.

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