spring refresh()

最新推荐文章于 2025-08-11 14:43:21 发布

原创最新推荐文章于 2025-08-11 14:43:21 发布 · 105 阅读

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本文详细解析了Spring容器启动过程中的关键步骤，包括初始化BeanFactory、加载Bean定义、注册Bean后处理器等，并提供了深入理解Spring框架内部机制所需的重要信息。

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public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			//准备启动spring容器，设置容器的启动日期和活动标志
			prepareRefresh();

			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();//获得容器ApplicationContext的子类BeanFactory。步骤如下：如果已经有了BeanFactory就销毁它里面的单例Bean并关闭这个BeanFactory。2.创建一个新的BeanFactory。3.对这个BeanFactory进行定制（customize),如allowBeanDefinitionOverriding，allowCircularReferences。4.装载BeanDefinitions(读取配置文件，将xml转换成对应得BeanDefinition)。5.检查是否同时启动了两个BeanFactory。  

			// 通过XmlBeanDefinitionReader加载bean定义.
			prepareBeanFactory(beanFactory);

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

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

				// 注册 bean processors 
				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) {
				// Destroy already created singletons to avoid dangling resources.
				destroyBeans();

				// Reset 'active' flag.
				cancelRefresh(ex);

				// Propagate exception to caller.
				throw ex;
			}
		}
	}

ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
此方法比较关键，代码也比较多


protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
		refreshBeanFactory();
		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
		if (logger.isDebugEnabled()) {
			logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);
		}
		return beanFactory;
	}

refreshBeanFactory();


@Override
	protected final void refreshBeanFactory() throws BeansException {
		if (hasBeanFactory()) {
			destroyBeans();
			closeBeanFactory();
		}
		try {
			DefaultListableBeanFactory beanFactory = createBeanFactory();
			beanFactory.setSerializationId(getId());
			customizeBeanFactory(beanFactory);
			loadBeanDefinitions(beanFactory);
			synchronized (this.beanFactoryMonitor) {
				this.beanFactory = beanFactory;
			}
		}
		catch (IOException ex) {
			throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);
		}
	}

loadBeanDefinitions(beanFactory);


@Override
	protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {
		// Create a new XmlBeanDefinitionReader for the given BeanFactory.
		XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory);

		// Configure the bean definition reader with this context's
		// resource loading environment.
		beanDefinitionReader.setEnvironment(this.getEnvironment());
		beanDefinitionReader.setResourceLoader(this);
		beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));

		// Allow a subclass to provide custom initialization of the reader,
		// then proceed with actually loading the bean definitions.
		initBeanDefinitionReader(beanDefinitionReader);
		loadBeanDefinitions(beanDefinitionReader);
	}

loadBeanDefinitions(beanDefinitionReader);装载xml文件到XmlBeanDefinitionReader的过程


protected void loadBeanDefinitions(XmlBeanDefinitionReader reader) throws BeansException, IOException {
		Resource[] configResources = getConfigResources();
		if (configResources != null) {
			reader.loadBeanDefinitions(configResources);
		}
		String[] configLocations = getConfigLocations();
		if (configLocations != null) {
			reader.loadBeanDefinitions(configLocations);
		}
	}

postProcessBeanFactory(beanFactory);
关于Spring的BeanPostProcessor就看参考下面的文章
http://blog.youkuaiyun.com/chensugang/article/details/3423650

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