ConfigurationClassPostProcessor解析

Z时代
2024-01-10
分类：综合

ConfigurationClassPostProcessor解析

主要是为了解析Configuration类

类图

何时使用

继承了BeanFactoryPostProcessor，会在容器加载的时候使用。

@Override
	public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			// Prepare this context for refreshing.
			prepareRefresh();
			// Tell the subclass to refresh the internal bean factory.
			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
			// Prepare the bean factory for use in this context.
			prepareBeanFactory(beanFactory);
			try {
				// Allows post-processing of the bean factory in context subclasses.
				postProcessBeanFactory(beanFactory);
				// Invoke factory processors registered as beans in the context.
				// 执行BeanFactoryPostProcessor
				invokeBeanFactoryPostProcessors(beanFactory);
				// Register bean processors that intercept bean creation.
				registerBeanPostProcessors(beanFactory);
				// Initialize message source for this context.
				initMessageSource();
				// Initialize event multicaster for this context.
				initApplicationEventMulticaster();
				// Initialize other special beans in specific context subclasses.
				onRefresh();
				// Check for listener beans and register them.
				registerListeners();
				// Instantiate all remaining (non-lazy-init) singletons.
				finishBeanFactoryInitialization(beanFactory);
				// Last step: publish corresponding event.
				finishRefresh();
			}
			catch (BeansException ex) {
				if (logger.isWarnEnabled()) {
					logger.warn("Exception encountered during context initialization - " +
							"cancelling refresh attempt: " + ex);
				}
				// Destroy already created singletons to avoid dangling resources.
				destroyBeans();
				// Reset "active" flag.
				cancelRefresh(ex);
				// Propagate exception to caller.
				throw ex;
			}
			finally {
				// Reset common introspection caches in Spring"s core, since we
				// might not ever need metadata for singleton beans anymore...
				resetCommonCaches();
			}
		}
	}

加载Configuration流程

入口方法：org.springframework.context.annotation.ConfigurationClassPostProcessor#postProcessBeanDefinitionRegistry

	@Override
	public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
		int registryId = System.identityHashCode(registry);
		if (this.registriesPostProcessed.contains(registryId)) {
			throw new IllegalStateException(
					"postProcessBeanDefinitionRegistry already called on this post-processor against " + registry);
		}
		if (this.factoriesPostProcessed.contains(registryId)) {
			throw new IllegalStateException(
					"postProcessBeanFactory already called on this post-processor against " + registry);
		}
		this.registriesPostProcessed.add(registryId);
		processConfigBeanDefinitions(registry);
	}

org.springframework.context.annotation.ConfigurationClassParser#parse(java.util.Set<org.springframework.beans.factory.config.BeanDefinitionHolder>)

this.deferredImportSelectorHandler.process();

org.springframework.context.annotation.ConfigurationClassParser.DeferredImportSelectorGroupingHandler#processGroupImports

org.springframework.context.annotation.ConfigurationClassParser.DeferredImportSelectorGrouping#getImports

org.springframework.boot.autoconfigure.AutoConfigurationImportSelector.AutoConfigurationGroup#process

org.springframework.boot.autoconfigure.AutoConfigurationImportSelector#getAutoConfigurationEntry

org.springframework.boot.autoconfigure.AutoConfigurationImportSelector#getCandidateConfigurations

protected List<String> getCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) {
		List<String> configurations = SpringFactoriesLoader.loadFactoryNames(getSpringFactoriesLoaderFactoryClass(),
				getBeanClassLoader());
	// 加载了所有的AutoConfiguration类
		Assert.notEmpty(configurations, "No auto configuration classes found in META-INF/spring.factories. If you "
				+ "are using a custom packaging, make sure that file is correct.");
		return configurations;
	}