Spring 注册内置后置处理器流程

版本

spring-context 5.3.13

注册流程

AnnotationConfigApplicationContext构造函数中完成了Spring内置的后置处理器。

public class AnnotationConfigApplicationContext extends GenericApplicationContext implements AnnotationConfigRegistry {
    public AnnotationConfigApplicationContext() {
        this.reader = new AnnotatedBeanDefinitionReader(this);
    }
}

public class AnnotatedBeanDefinitionReader {
    public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry) {
        this(registry, getOrCreateEnvironment(registry));
    }

    public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry, Environment environment) {
        AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
    }
}

public abstract class AnnotationConfigUtils {
    public static void registerAnnotationConfigProcessors(BeanDefinitionRegistry registry) {
        registerAnnotationConfigProcessors(registry, null);
    }

    public static final String CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME =
            "org.springframework.context.annotation.internalConfigurationAnnotationProcessor";

    public static final String AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME =
            "org.springframework.context.annotation.internalAutowiredAnnotationProcessor";

    public static final String COMMON_ANNOTATION_PROCESSOR_BEAN_NAME =
            "org.springframework.context.annotation.internalCommonAnnotationProcessor";

    public static final String EVENT_LISTENER_PROCESSOR_BEAN_NAME =
            "org.springframework.context.event.internalEventListenerProcessor";

    public static final String EVENT_LISTENER_FACTORY_BEAN_NAME =
            "org.springframework.context.event.internalEventListenerFactory";

    public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(BeanDefinitionRegistry registry, @Nullable Object source) {

        DefaultListableBeanFactory beanFactory = unwrapDefaultListableBeanFactory(registry);

        Set<BeanDefinitionHolder> beanDefs = new LinkedHashSet<>(8);

        if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {
            RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);
            def.setSource(source);
            // 调用自己的私有方法 registerPostProcessor 注册后置处理器
            beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));
        }

        if (!registry.containsBeanDefinition(AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) {
            RootBeanDefinition def = new RootBeanDefinition(AutowiredAnnotationBeanPostProcessor.class);
            def.setSource(source);
            beanDefs.add(registerPostProcessor(registry, def, AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME));
        }

        // Check for JSR-250 support, and if present add the CommonAnnotationBeanPostProcessor.
        if (jsr250Present && !registry.containsBeanDefinition(COMMON_ANNOTATION_PROCESSOR_BEAN_NAME)) {
            RootBeanDefinition def = new RootBeanDefinition(CommonAnnotationBeanPostProcessor.class);
            def.setSource(source);
            beanDefs.add(registerPostProcessor(registry, def, COMMON_ANNOTATION_PROCESSOR_BEAN_NAME));
        }

        if (!registry.containsBeanDefinition(EVENT_LISTENER_PROCESSOR_BEAN_NAME)) {
            RootBeanDefinition def = new RootBeanDefinition(EventListenerMethodProcessor.class);
            def.setSource(source);
            beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_PROCESSOR_BEAN_NAME));
        }

        if (!registry.containsBeanDefinition(EVENT_LISTENER_FACTORY_BEAN_NAME)) {
            RootBeanDefinition def = new RootBeanDefinition(DefaultEventListenerFactory.class);
            def.setSource(source);
            beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_FACTORY_BEAN_NAME));
        }

        return beanDefs;
    }

    private static BeanDefinitionHolder registerPostProcessor(BeanDefinitionRegistry registry, RootBeanDefinition definition, String beanName) {
        definition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
        // 调用 GenericApplicationContext 中复写的方法
        registry.registerBeanDefinition(beanName, definition);
        return new BeanDefinitionHolder(definition, beanName);
    }
}

public class GenericApplicationContext extends AbstractApplicationContext implements BeanDefinitionRegistry {
    @Override
    public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition) throws BeanDefinitionStoreException {
        // 调用 DefaultListableBeanFactory 中复写的方法
        this.beanFactory.registerBeanDefinition(beanName, beanDefinition);
    }
}

public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFactory implements ConfigurableListableBeanFactory, BeanDefinitionRegistry, Serializable {

    private final Map<String, BeanDefinition> beanDefinitionMap = new ConcurrentHashMap<>(256);

    @Override
    public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition) throws BeanDefinitionStoreException {
        BeanDefinition existingDefinition = this.beanDefinitionMap.get(beanName);
        if (existingDefinition != null) {
            // ...
        } else {
            if (hasBeanCreationStarted()) {
                // ...
            } else {
                // 将 BeanDefinition 信息放入 map 中
                this.beanDefinitionMap.put(beanName, beanDefinition);
            }
        }
    }
}

完整调用栈

registerBeanDefinition:1035, DefaultListableBeanFactory (org.springframework.beans.factory.support)
registerBeanDefinition:330, GenericApplicationContext (org.springframework.context.support)
registerPostProcessor:216, AnnotationConfigUtils (org.springframework.context.annotation)
registerAnnotationConfigProcessors:166, AnnotationConfigUtils (org.springframework.context.annotation)
registerAnnotationConfigProcessors:137, AnnotationConfigUtils (org.springframework.context.annotation)
<init>:88, AnnotatedBeanDefinitionReader (org.springframework.context.annotation)
<init>:71, AnnotatedBeanDefinitionReader (org.springframework.context.annotation)
<init>:69, AnnotationConfigApplicationContext (org.springframework.context.annotation)
main:24, Test7 (com.example.learn)