758 lines
30 KiB
Markdown
758 lines
30 KiB
Markdown
# 【死磕 Spring】—— 深入分析 ApplicationContext 的 refresh()
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**本文主要基于 Spring 5.0.6.RELEASE**
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摘要: 原创出处 http://cmsblogs.com/?p=todo 「小明哥」，谢谢！
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作为「小明哥」的忠实读者，「老艿艿」略作修改，记录在理解过程中，参考的资料。
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------
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上篇博客只是对 ApplicationContext 相关的接口做了一个简单的介绍，作为一个高富帅级别的 Spring 容器，它涉及的方法实在是太多了，全部介绍是不可能的，而且大部分功能都已经在前面系列博客中做了详细的介绍，所以这篇博问介绍 ApplicationContext 最重要的方法（小编认为的） ：`#refresh()` 方法。
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> 艿艿：我也这么认为，`#refresh()` 方法是关键的关键！
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`#refresh()` 方法，是定义在 ConfigurableApplicationContext 类中的，如下：
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```
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// ConfigurableApplicationContext.java
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/**
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* Load or refresh the persistent representation of the configuration,
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* which might an XML file, properties file, or relational database schema.
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* As this is a startup method, it should destroy already created singletons
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* if it fails, to avoid dangling resources. In other words, after invocation
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* of that method, either all or no singletons at all should be instantiated.
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* @throws BeansException if the bean factory could not be initialized
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* @throws IllegalStateException if already initialized and multiple refresh
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* attempts are not supported
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*/
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void refresh() throws BeansException, IllegalStateException;
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```
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- 作用就是：**刷新 Spring 的应用上下文**。
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其实现是在 AbstractApplicationContext 中实现。如下：
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```
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// AbstractApplicationContext.java
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@Override
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public void refresh() throws BeansException, IllegalStateException {
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synchronized (this.startupShutdownMonitor) {
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// 准备刷新上下文环境
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prepareRefresh();
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// 创建并初始化 BeanFactory
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ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
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// 填充BeanFactory功能
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prepareBeanFactory(beanFactory);
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try {
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// 提供子类覆盖的额外处理，即子类处理自定义的BeanFactoryPostProcess
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postProcessBeanFactory(beanFactory);
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// 激活各种BeanFactory处理器
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invokeBeanFactoryPostProcessors(beanFactory);
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// 注册拦截Bean创建的Bean处理器，即注册 BeanPostProcessor
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registerBeanPostProcessors(beanFactory);
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// 初始化上下文中的资源文件，如国际化文件的处理等
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initMessageSource();
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// 初始化上下文事件广播器
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initApplicationEventMulticaster();
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// 给子类扩展初始化其他Bean
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onRefresh();
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// 在所有bean中查找listener bean，然后注册到广播器中
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registerListeners();
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// 初始化剩下的单例Bean(非延迟加载的)
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finishBeanFactoryInitialization(beanFactory);
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// 完成刷新过程,通知生命周期处理器lifecycleProcessor刷新过程,同时发出ContextRefreshEvent通知别人
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finishRefresh();
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} catch (BeansException ex) {
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if (logger.isWarnEnabled()) {
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logger.warn("Exception encountered during context initialization - " +
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"cancelling refresh attempt: " + ex);
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}
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// 销毁已经创建的Bean
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destroyBeans();
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// 重置容器激活标签
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cancelRefresh(ex);
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// 抛出异常
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throw ex;
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} finally {
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// Reset common introspection caches in Spring's core, since we
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// might not ever need metadata for singleton beans anymore...
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resetCommonCaches();
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}
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}
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}
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```
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这里每一个方法都非常重要，需要一个一个地解释说明。
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# 1. prepareRefresh()
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> 初始化上下文环境，对系统的环境变量或者系统属性进行准备和校验,如环境变量中必须设置某个值才能运行，否则不能运行，这个时候可以在这里加这个校验，重写 initPropertySources 方法就好了
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```
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// AbstractApplicationContext.java
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protected void prepareRefresh() {
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// 设置启动日期
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this.startupDate = System.currentTimeMillis();
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// 设置 context 当前状态
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this.closed.set(false);
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this.active.set(true);
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if (logger.isInfoEnabled()) {
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logger.info("Refreshing " + this);
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}
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// 初始化context environment（上下文环境）中的占位符属性来源
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initPropertySources();
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// 对属性进行必要的验证
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getEnvironment().validateRequiredProperties();
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this.earlyApplicationEvents = new LinkedHashSet<>();
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}
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```
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该方法主要是做一些准备工作，如：
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1. 设置 context 启动时间
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2. 设置 context 的当前状态
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3. 初始化 context environment 中占位符
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4. 对属性进行必要的验证
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# 2. obtainFreshBeanFactory()
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> 创建并初始化 BeanFactory
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```
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// AbstractApplicationContext.java
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protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
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// 刷新 BeanFactory
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refreshBeanFactory();
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// 获取 BeanFactory
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ConfigurableListableBeanFactory beanFactory = getBeanFactory();
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if (logger.isDebugEnabled()) {
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logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);
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}
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return beanFactory;
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}
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```
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核心方法就在 `#refreshBeanFactory()` 方法，该方法的核心任务就是创建 BeanFactory 并对其就行一番初始化。如下：
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```
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// AbstractRefreshableApplicationContext.java
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@Override
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protected final void refreshBeanFactory() throws BeansException {
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// 若已有 BeanFactory ，销毁它的 Bean 们，并销毁 BeanFactory
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if (hasBeanFactory()) {
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destroyBeans();
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closeBeanFactory();
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}
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try {
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// 创建 BeanFactory 对象
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DefaultListableBeanFactory beanFactory = createBeanFactory();
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// 指定序列化编号
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beanFactory.setSerializationId(getId());
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// 定制 BeanFactory 设置相关属性
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customizeBeanFactory(beanFactory);
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// 加载 BeanDefinition 们
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loadBeanDefinitions(beanFactory);
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// 设置 Context 的 BeanFactory
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synchronized (this.beanFactoryMonitor) {
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this.beanFactory = beanFactory;
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}
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} catch (IOException ex) {
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throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);
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}
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}
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```
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1. 判断当前容器是否存在一个 BeanFactory，如果存在则对其进行销毁和关闭
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2. 调用 `#createBeanFactory()` 方法，创建一个 BeanFactory 实例，其实就是 DefaultListableBeanFactory 。
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3. 自定义 BeanFactory
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4. 加载 BeanDefinition 。
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5. 将创建好的 bean 工厂的引用交给的 context 来管理
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上面 5 个步骤，都是比较简单的，但是有必要讲解下第 4 步：加载 BeanDefinition。如果各位看过 【死磕 Spring】系列的话，在刚刚开始分析源码的时候，小编就是以 `BeanDefinitionReader#loadBeanDefinitions(Resource resource)` 方法，作为入口来分析的，示例如下：
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```
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// 示例代码
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ClassPathResource resource = new ClassPathResource("bean.xml");
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DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
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XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(factory);
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reader.loadBeanDefinitions(resource);
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```
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只不过这段代码的 `BeanDefinitionReader#loadBeanDefinitions(Resource)` 方法，是定义在 BeanDefinitionReader 中，而此处的 `#loadBeanDefinitions(DefaultListableBeanFactory beanFactory)` 则是定义在 AbstractRefreshableApplicationContext 中，如下：
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```
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// AbstractRefreshableApplicationContext.java
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protected abstract void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException
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```
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由具体的子类实现，我们以 AbstractXmlApplicationContext 为例，实现如下：
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```
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// AbstractXmlApplicationContext.java
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@Override
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protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {
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// Create a new XmlBeanDefinitionReader for the given BeanFactory.
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// 创建 XmlBeanDefinitionReader 对象
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XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory);
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// Configure the bean definition reader with this context's
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// resource loading environment.
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// 对 XmlBeanDefinitionReader 进行环境变量的设置
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beanDefinitionReader.setEnvironment(this.getEnvironment());
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beanDefinitionReader.setResourceLoader(this);
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beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));
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// Allow a subclass to provide custom initialization of the reader,
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// then proceed with actually loading the bean definitions.
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// 对 XmlBeanDefinitionReader 进行设置，可以进行覆盖
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initBeanDefinitionReader(beanDefinitionReader);
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// 从 Resource 们中，加载 BeanDefinition 们
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loadBeanDefinitions(beanDefinitionReader);
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}
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```
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- 新建 XmlBeanDefinitionReader 实例对象 beanDefinitionReader，调用 `initBeanDefinitionReader()` 对其进行初始化，然后调用 `loadBeanDefinitions()` 加载 BeanDefinition。代码如下：
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```
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// AbstractXmlApplicationContext.java
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protected void loadBeanDefinitions(XmlBeanDefinitionReader reader) throws BeansException, IOException {
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// 从配置文件 Resource 中，加载 BeanDefinition 们
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Resource[] configResources = getConfigResources();
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if (configResources != null) {
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reader.loadBeanDefinitions(configResources);
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}
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// 从配置文件地址中，加载 BeanDefinition 们
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String[] configLocations = getConfigLocations();
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if (configLocations != null) {
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reader.loadBeanDefinitions(configLocations);
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}
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}
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```
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- 到这里我们发现，其实内部依然是调用 `BeanDefinitionReader#loadBeanDefinitionn()` 进行 BeanDefinition 的加载进程。
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# 3. prepareBeanFactory(beanFactory)
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> 填充 BeanFactory 功能
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上面获取获取的 BeanFactory 除了加载了一些 BeanDefinition 就没有其他任何东西了，这个时候其实还不能投入生产，因为还少配置了一些东西，比如 context的 ClassLoader 和 后置处理器等等。
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```
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// AbstractApplicationContext.java
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protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
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// 设置beanFactory的classLoader
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beanFactory.setBeanClassLoader(getClassLoader());
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// 设置beanFactory的表达式语言处理器,Spring3开始增加了对语言表达式的支持,默认可以使用#{bean.xxx}的形式来调用相关属性值
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beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
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// 为beanFactory增加一个默认的propertyEditor
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beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
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// 添加ApplicationContextAwareProcessor
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beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
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// 设置忽略自动装配的接口
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beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
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beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
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beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
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beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
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beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
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beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
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// 设置几个自动装配的特殊规则
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beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
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beanFactory.registerResolvableDependency(ResourceLoader.class, this);
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beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
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beanFactory.registerResolvableDependency(ApplicationContext.class, this);
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// Register early post-processor for detecting inner beans as ApplicationListeners.
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beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
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// 增加对AspectJ的支持
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if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
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beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
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// Set a temporary ClassLoader for type matching.
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beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
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}
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// 注册默认的系统环境bean
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if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
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beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
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}
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if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {
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beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
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}
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if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {
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beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
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}
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}
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```
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看上面的源码知道这个就是对 BeanFactory 设置各种各种的功能。
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# 4. postProcessBeanFactory()
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> 提供子类覆盖的额外处理，即子类处理自定义的BeanFactoryPostProcess
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```
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// AbstractApplicationContext.java
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protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
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beanFactory.addBeanPostProcessor(new ServletContextAwareProcessor(this.servletContext, this.servletConfig));
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beanFactory.ignoreDependencyInterface(ServletContextAware.class);
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beanFactory.ignoreDependencyInterface(ServletConfigAware.class);
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WebApplicationContextUtils.registerWebApplicationScopes(beanFactory, this.servletContext);
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WebApplicationContextUtils.registerEnvironmentBeans(beanFactory, this.servletContext, this.servletConfig);
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}
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```
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1. 添加 ServletContextAwareProcessor 到 BeanFactory 容器中，该 processor 实现 BeanPostProcessor 接口，主要用于将ServletContext 传递给实现了 ServletContextAware 接口的 bean
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2. 忽略 ServletContextAware、ServletConfigAware
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3. 注册 WEB 应用特定的域（scope）到 beanFactory 中，以便 WebApplicationContext 可以使用它们。比如 “request” , “session” , “globalSession” , “application”
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4. 注册 WEB 应用特定的 Environment bean 到 beanFactory 中，以便WebApplicationContext 可以使用它们。如：”contextParameters”, “contextAttributes”
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# 5. invokeBeanFactoryPostProcessors()
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> 激活各种BeanFactory处理器
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```
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// AbstractApplicationContext.java
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public static void invokeBeanFactoryPostProcessors(
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ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
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// 定义一个 set 保存所有的 BeanFactoryPostProcessors
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Set<String> processedBeans = new HashSet<>();
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// 如果当前 BeanFactory 为 BeanDefinitionRegistry
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if (beanFactory instanceof BeanDefinitionRegistry) {
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BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
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// BeanFactoryPostProcessor 集合
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List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
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// BeanDefinitionRegistryPostProcessor 集合
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List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
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// 迭代注册的 beanFactoryPostProcessors
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for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
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// 如果是 BeanDefinitionRegistryPostProcessor，则调用 postProcessBeanDefinitionRegistry 进行注册，
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// 同时加入到 registryProcessors 集合中
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if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
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BeanDefinitionRegistryPostProcessor registryProcessor =
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(BeanDefinitionRegistryPostProcessor) postProcessor;
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registryProcessor.postProcessBeanDefinitionRegistry(registry);
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registryProcessors.add(registryProcessor);
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}
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else {
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// 否则当做普通的 BeanFactoryPostProcessor 处理
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// 添加到 regularPostProcessors 集合中即可，便于后面做后续处理
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regularPostProcessors.add(postProcessor);
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}
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}
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// 用于保存当前处理的 BeanDefinitionRegistryPostProcessor
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List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
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// 首先处理实现了 PriorityOrdered (有限排序接口)的 BeanDefinitionRegistryPostProcessor
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String[] postProcessorNames =
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beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
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for (String ppName : postProcessorNames) {
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if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
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currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
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processedBeans.add(ppName);
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}
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}
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// 排序
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sortPostProcessors(currentRegistryProcessors, beanFactory);
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// 加入registryProcessors集合
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registryProcessors.addAll(currentRegistryProcessors);
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// 调用所有实现了 PriorityOrdered 的 BeanDefinitionRegistryPostProcessors 的 postProcessBeanDefinitionRegistry()
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invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
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// 清空，以备下次使用
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currentRegistryProcessors.clear();
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// 其次，调用是实现了 Ordered（普通排序接口）的 BeanDefinitionRegistryPostProcessors
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// 逻辑和 上面一样
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postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
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for (String ppName : postProcessorNames) {
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if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
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currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
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processedBeans.add(ppName);
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}
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}
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sortPostProcessors(currentRegistryProcessors, beanFactory);
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registryProcessors.addAll(currentRegistryProcessors);
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invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
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currentRegistryProcessors.clear();
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// 最后调用其他的 BeanDefinitionRegistryPostProcessors
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boolean reiterate = true;
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while (reiterate) {
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reiterate = false;
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// 获取 BeanDefinitionRegistryPostProcessor
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postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
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for (String ppName : postProcessorNames) {
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// 没有包含在 processedBeans 中的（因为包含了的都已经处理了）
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if (!processedBeans.contains(ppName)) {
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currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
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processedBeans.add(ppName);
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reiterate = true;
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}
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}
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// 与上面处理逻辑一致
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sortPostProcessors(currentRegistryProcessors, beanFactory);
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registryProcessors.addAll(currentRegistryProcessors);
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invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
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currentRegistryProcessors.clear();
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}
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// 调用所有 BeanDefinitionRegistryPostProcessor (包括手动注册和通过配置文件注册)
|
||
// 和 BeanFactoryPostProcessor(只有手动注册)的回调函数(postProcessBeanFactory())
|
||
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
|
||
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
|
||
}
|
||
|
||
else {
|
||
// 如果不是 BeanDefinitionRegistry 只需要调用其回调函数（postProcessBeanFactory()）即可
|
||
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
|
||
}
|
||
|
||
//
|
||
String[] postProcessorNames =
|
||
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
|
||
|
||
// 这里同样需要区分 PriorityOrdered 、Ordered 和 no Ordered
|
||
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
|
||
List<String> orderedPostProcessorNames = new ArrayList<>();
|
||
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
|
||
for (String ppName : postProcessorNames) {
|
||
// 已经处理过了的，跳过
|
||
if (processedBeans.contains(ppName)) {
|
||
// skip - already processed in first phase above
|
||
}
|
||
// PriorityOrdered
|
||
else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
|
||
priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
|
||
}
|
||
// Ordered
|
||
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
|
||
orderedPostProcessorNames.add(ppName);
|
||
}
|
||
// no Ordered
|
||
else {
|
||
nonOrderedPostProcessorNames.add(ppName);
|
||
}
|
||
}
|
||
|
||
// First, PriorityOrdered 接口
|
||
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
|
||
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
|
||
|
||
// Next, Ordered 接口
|
||
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>();
|
||
for (String postProcessorName : orderedPostProcessorNames) {
|
||
orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
|
||
}
|
||
sortPostProcessors(orderedPostProcessors, beanFactory);
|
||
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
|
||
|
||
// Finally, no ordered
|
||
List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
|
||
for (String postProcessorName : nonOrderedPostProcessorNames) {
|
||
nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
|
||
}
|
||
invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
|
||
|
||
// Clear cached merged bean definitions since the post-processors might have
|
||
// modified the original metadata, e.g. replacing placeholders in values...
|
||
beanFactory.clearMetadataCache();
|
||
}
|
||
```
|
||
|
||
上述代码较长，但是处理逻辑较为单一，就是对所有的 BeanDefinitionRegistryPostProcessors 、手动注册的 BeanFactoryPostProcessor 以及通过配置文件方式的 BeanFactoryPostProcessor 按照 PriorityOrdered 、 Ordered、no ordered 三种方式分开处理、调用。
|
||
|
||
# 6. registerBeanPostProcessors
|
||
|
||
> 注册拦截Bean创建的Bean处理器，即注册 BeanPostProcessor
|
||
|
||
与 BeanFactoryPostProcessor 一样，也是委托给 PostProcessorRegistrationDelegate 来实现的。
|
||
|
||
```
|
||
// AbstractApplicationContext.java
|
||
|
||
public static void registerBeanPostProcessors(
|
||
ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
|
||
|
||
// 所有的 BeanPostProcessors
|
||
String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
|
||
|
||
// 注册 BeanPostProcessorChecker
|
||
// 主要用于记录一些 bean 的信息，这些 bean 不符合所有 BeanPostProcessors 处理的资格时
|
||
int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
|
||
beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
|
||
|
||
// 区分 PriorityOrdered、Ordered 、 no ordered
|
||
List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
|
||
List<String> orderedPostProcessorNames = new ArrayList<>();
|
||
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
|
||
// MergedBeanDefinition
|
||
List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
|
||
for (String ppName : postProcessorNames) {
|
||
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
|
||
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
|
||
priorityOrderedPostProcessors.add(pp);
|
||
if (pp instanceof MergedBeanDefinitionPostProcessor) {
|
||
internalPostProcessors.add(pp);
|
||
}
|
||
}
|
||
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
|
||
orderedPostProcessorNames.add(ppName);
|
||
}
|
||
else {
|
||
nonOrderedPostProcessorNames.add(ppName);
|
||
}
|
||
}
|
||
|
||
// First, PriorityOrdered
|
||
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
|
||
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
|
||
|
||
// Next, Ordered
|
||
List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>();
|
||
for (String ppName : orderedPostProcessorNames) {
|
||
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
|
||
orderedPostProcessors.add(pp);
|
||
if (pp instanceof MergedBeanDefinitionPostProcessor) {
|
||
internalPostProcessors.add(pp);
|
||
}
|
||
}
|
||
sortPostProcessors(orderedPostProcessors, beanFactory);
|
||
registerBeanPostProcessors(beanFactory, orderedPostProcessors);
|
||
|
||
// onOrdered
|
||
List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
|
||
for (String ppName : nonOrderedPostProcessorNames) {
|
||
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
|
||
nonOrderedPostProcessors.add(pp);
|
||
if (pp instanceof MergedBeanDefinitionPostProcessor) {
|
||
internalPostProcessors.add(pp);
|
||
}
|
||
}
|
||
registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
|
||
|
||
// Finally, all internal BeanPostProcessors.
|
||
sortPostProcessors(internalPostProcessors, beanFactory);
|
||
registerBeanPostProcessors(beanFactory, internalPostProcessors);
|
||
|
||
// 重新注册用来自动探测内部ApplicationListener的post-processor，这样可以将他们移到处理器链条的末尾
|
||
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
|
||
}
|
||
```
|
||
|
||
# 7. initMessageSource
|
||
|
||
> 初始化上下文中的资源文件，如国际化文件的处理等
|
||
|
||
其实该方法就是初始化一个 MessageSource 接口的实现类，主要用于国际化/i18n。
|
||
|
||
```
|
||
// AbstractApplicationContext.java
|
||
|
||
protected void initMessageSource() {
|
||
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
|
||
// 包含 “messageSource” bean
|
||
if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) {
|
||
this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class);
|
||
// 如果有父类
|
||
// HierarchicalMessageSource 分级处理的 MessageSource
|
||
if (this.parent != null && this.messageSource instanceof HierarchicalMessageSource) {
|
||
HierarchicalMessageSource hms = (HierarchicalMessageSource) this.messageSource;
|
||
if (hms.getParentMessageSource() == null) {
|
||
// 如果没有注册父 MessageSource，则设置为父类上下文的的 MessageSource
|
||
hms.setParentMessageSource(getInternalParentMessageSource());
|
||
}
|
||
}
|
||
if (logger.isDebugEnabled()) {
|
||
logger.debug("Using MessageSource [" + this.messageSource + "]");
|
||
}
|
||
}
|
||
else {
|
||
// 使用 空 MessageSource
|
||
DelegatingMessageSource dms = new DelegatingMessageSource();
|
||
dms.setParentMessageSource(getInternalParentMessageSource());
|
||
this.messageSource = dms;
|
||
beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource);
|
||
if (logger.isDebugEnabled()) {
|
||
logger.debug("Unable to locate MessageSource with name '" + MESSAGE_SOURCE_BEAN_NAME +
|
||
"': using default [" + this.messageSource + "]");
|
||
}
|
||
}
|
||
}
|
||
```
|
||
|
||
# 8. initApplicationEventMulticaster
|
||
|
||
> 初始化上下文事件广播器
|
||
|
||
```
|
||
// AbstractApplicationContext.java
|
||
|
||
protected void initApplicationEventMulticaster() {
|
||
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
|
||
|
||
// 如果存在 applicationEventMulticaster bean，则获取赋值
|
||
if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
|
||
this.applicationEventMulticaster =
|
||
beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
|
||
if (logger.isDebugEnabled()) {
|
||
logger.debug("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
|
||
}
|
||
}
|
||
else {
|
||
// 没有则新建 SimpleApplicationEventMulticaster，并完成 bean 的注册
|
||
this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
|
||
beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
|
||
if (logger.isDebugEnabled()) {
|
||
logger.debug("Unable to locate ApplicationEventMulticaster with name '" +
|
||
APPLICATION_EVENT_MULTICASTER_BEAN_NAME +
|
||
"': using default [" + this.applicationEventMulticaster + "]");
|
||
}
|
||
}
|
||
}
|
||
```
|
||
|
||
如果当前容器中存在 applicationEventMulticaster 的 bean，则对 applicationEventMulticaster 赋值，否则新建一个 SimpleApplicationEventMulticaster 的对象（默认的），并完成注册。
|
||
|
||
# 9. onRefresh
|
||
|
||
> 给子类扩展初始化其他Bean
|
||
|
||
预留给 AbstractApplicationContext 的子类用于初始化其他特殊的 bean，该方法需要在所有单例 bean 初始化之前调用。
|
||
|
||
# 10. registerListeners
|
||
|
||
> 在所有 bean 中查找 listener bean，然后注册到广播器中
|
||
|
||
```
|
||
// AbstractApplicationContext.java
|
||
|
||
protected void registerListeners() {
|
||
// 注册静态 监听器
|
||
for (ApplicationListener<?> listener : getApplicationListeners()) {
|
||
getApplicationEventMulticaster().addApplicationListener(listener);
|
||
}
|
||
|
||
String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
|
||
for (String listenerBeanName : listenerBeanNames) {
|
||
getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
|
||
}
|
||
|
||
// 至此，已经完成将监听器注册到ApplicationEventMulticaster中，下面将发布前期的事件给监听器。
|
||
Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
|
||
this.earlyApplicationEvents = null;
|
||
if (earlyEventsToProcess != null) {
|
||
for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
|
||
getApplicationEventMulticaster().multicastEvent(earlyEvent);
|
||
}
|
||
}
|
||
}
|
||
```
|
||
|
||
# 10. finishBeanFactoryInitialization
|
||
|
||
> 初始化剩下的单例Bean(非延迟加载的)
|
||
|
||
```
|
||
// AbstractApplicationContext.java
|
||
|
||
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
|
||
// 初始化转换器
|
||
if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) &&
|
||
beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) {
|
||
beanFactory.setConversionService(
|
||
beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class));
|
||
}
|
||
|
||
// 如果之前没有注册 bean 后置处理器（例如PropertyPlaceholderConfigurer），则注册默认的解析器
|
||
if (!beanFactory.hasEmbeddedValueResolver()) {
|
||
beanFactory.addEmbeddedValueResolver(strVal -> getEnvironment().resolvePlaceholders(strVal));
|
||
}
|
||
|
||
// 初始化 Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early.
|
||
String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
|
||
for (String weaverAwareName : weaverAwareNames) {
|
||
getBean(weaverAwareName);
|
||
}
|
||
|
||
// 停止使用临时的 ClassLoader
|
||
beanFactory.setTempClassLoader(null);
|
||
|
||
//
|
||
beanFactory.freezeConfiguration();
|
||
|
||
// 初始化所有剩余的单例（非延迟初始化）
|
||
beanFactory.preInstantiateSingletons();
|
||
}
|
||
```
|
||
|
||
# 11. finishRefresh
|
||
|
||
> 完成刷新过程,通知生命周期处理器 lifecycleProcessor 刷新过程,同时发出 ContextRefreshEvent 通知别人
|
||
|
||
主要是调用 `LifecycleProcessor#onRefresh()` ，并且发布事件（ContextRefreshedEvent）。
|
||
|
||
```
|
||
// AbstractApplicationContext.java
|
||
|
||
protected void finishRefresh() {
|
||
// Clear context-level resource caches (such as ASM metadata from scanning).
|
||
clearResourceCaches();
|
||
|
||
// Initialize lifecycle processor for this context.
|
||
initLifecycleProcessor();
|
||
|
||
// Propagate refresh to lifecycle processor first.
|
||
getLifecycleProcessor().onRefresh();
|
||
|
||
// Publish the final event.
|
||
publishEvent(new ContextRefreshedEvent(this));
|
||
|
||
// Participate in LiveBeansView MBean, if active.
|
||
LiveBeansView.registerApplicationContext(this);
|
||
}
|
||
``` |