SpringIOC容器创建过程

佚名 6年前 (2019-04-24) 随笔 1209人围观抢沙发百度已收录

在测试时，经常使用这种方式来创建spring容器

//创建基于注解的springIOC容器
ApplicationContext applicationContext = new AnnotationConfigApplicationContext(AopBeanConfig.class);
//创建基于配置文件的springIOC容器
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("/spring-beans.xml");

无论哪种方式，最终都会调用AbstractApplicationContext的一个重要方法——refresh()，首先来看这个方法的spring源码

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    @Override
    public void refresh() throws BeansException, IllegalStateException {
        synchronized (this.startupShutdownMonitor) {
            // 1. Prepare this context for refreshing.
            prepareRefresh();

            // 2. Tell the subclass to refresh the internal bean factory. 
            ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

            // 3. Prepare the bean factory for use in this context. 
            prepareBeanFactory(beanFactory);

            try {
                // 4. Allows post-processing of the bean factory in context subclasses.
                postProcessBeanFactory(beanFactory);

                // 5. Invoke factory processors registered as beans in the context.
                invokeBeanFactoryPostProcessors(beanFactory);

                // 6. Register bean processors that intercept bean creation.
                registerBeanPostProcessors(beanFactory);

                // 7. Initialize message source for this context.
                initMessageSource();

                // 8. Initialize event multicaster for this context.
                initApplicationEventMulticaster();

                // 9. Initialize other special beans in specific context subclasses.
                onRefresh();

                // 10. Check for listener beans and register them.
                registerListeners();

                // 11. Instantiate all remaining (non-lazy-init) singletons.
                finishBeanFactoryInitialization(beanFactory);

                // 12. 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();
            }
        }
    }