工作内容

该方法会实例化所有剩余的非懒加载单例 bean。
除一些内部的 bean、实现了 BeanFactoryPostProcessor 接口的 bean、实现了 BeanPostProcessor 接口的 bean，
其他的非懒加载单例 bean 都会在这个方法中被实例化。

  1. protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
  2.     // Initialize conversion service for this context.
  3.     // 注册 ConversionService
  4.     if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) &&
  5.             beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) {
  6.         beanFactory.setConversionService(
  7.                 beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class));
  8.     }
  10.     // Register a default embedded value resolver if no BeanFactoryPostProcessor
  11.     // (such as a PropertySourcesPlaceholderConfigurer bean) registered any before:
  12.     // at this point, primarily for resolution in annotation attribute values.
  13.     // 如果没有值解析器，就添加一个
  14.     if (!beanFactory.hasEmbeddedValueResolver()) {
  15.         beanFactory.addEmbeddedValueResolver(strVal -> getEnvironment().resolvePlaceholders(strVal));
  16.     }
  18.     // Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early.
  19.     String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
  20.     for (String weaverAwareName : weaverAwareNames) {
  21.         getBean(weaverAwareName);
  22.     }
  24.     // Stop using the temporary ClassLoader for type matching.
  25.     // 取消临时的类加载器
  26.     beanFactory.setTempClassLoader(null);
  28.     // bean 定义元数据不能再修改了
  29.     // Allow for caching all bean definition metadata, not expecting further changes.
  30.     beanFactory.freezeConfiguration();
  32.     // Instantiate all remaining (non-lazy-init) singletons.
  33.     // 实例化剩余的不是懒加载的单例bean
  34.     beanFactory.preInstantiateSingletons();
  35. }

附件

finishBeanFactoryInitialization.drawio.zip