--- layout: post title: Spring源码阅读笔记（1） category: 技术 tags: Spring keywords: description: IOC容器的初始化过程 --- {:toc} ## 1.IOC容器初始化过程 - Resource定位 **以FileSystemXmlApplicationContext的资源定义调用为例** [ FileSystemXmlApplicationContext(configLocations,refresh,parent)](){:title="org.springframework.context.support.FileSystemXmlApplicationContext.FileSystemXmlApplicationContext(String[], boolean, ApplicationContext)"} => [refresh()](){:title="org.springframework.context.support.AbstractApplicationContext.refresh()"} => [obtainFreshBeanFactory()](){:title="org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory()"} => [refreshBeanFactory()](){:title="org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory()"} => [loadBeanDefinitions(beanFactory)](){:title="org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(DefaultListableBeanFactory)"} => [loadBeanDefinitions(beanDefinitionReader)](){:title="org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(XmlBeanDefinitionReader)"} => [reader.loadBeanDefinitions(configLocations)](){:title="org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(String...)"} => [loadBeanDefinitions(locations)](){:title="org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(String...)"} => [loadBeanDefinitions(location)](){:title="org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(String)"} => [loadBeanDefinitions(location,null)](){:title="org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(String, Set)"} => [resourceLoader.getResource(location)](){:title="org.springframework.context.support.GenericApplicationContext.getResource(String)"} => [this.resourceLoader.getResource(location)](){:title="org.springframework.core.io.DefaultResourceLoader.getResource(String)"} => [getResourceByPath(location)](){:title="org.springframework.context.support.FileSystemXmlApplicationContext.getResourceByPath(String)"} => [FileSystemXmlApplicationContext](){:title="org.springframework.context.support.FileSystemXmlApplicationContext"} **结束** - BeanDefinition载入 [ FileSystemXmlApplicationContext(configLocations,refresh,parent)](){:title="org.springframework.context.support.FileSystemXmlApplicationContext.FileSystemXmlApplicationContext(String[], boolean, ApplicationContext)"} => [refresh()](){:title="org.springframework.context.support.AbstractApplicationContext.refresh()"} => [obtainFreshBeanFactory()](){:title="org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory()"} => [refreshBeanFactory()](){:title="org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory()"} => [loadBeanDefinitions(beanFactory)](){:title="org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(DefaultListableBeanFactory)"} => [loadBeanDefinitions(beanDefinitionReader)](){:title="org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(XmlBeanDefinitionReader)"} => [reader.loadBeanDefinitions(configLocations)](){:title="org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(String...)"} => [loadBeanDefinitions(locations)](){:title="org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(String...)"} => [loadBeanDefinitions(location)](){:title="org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(String)"} => [loadBeanDefinitions(location,null)](){:title="org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(String, Set)"} => [loadBeanDefinitions(resources)](){:title="org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(Resource...)"} => [loadBeanDefinitions(resource)](){:title="org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(Resource)"} => [loadBeanDefinitions(new EncodedResource(resource))](){:title="org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(EncodedResource)"} => [doLoadBeanDefinitions(inputSource, encodedResource.getResource())](){:title="org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(InputSource, Resource)"} => [registerBeanDefinitions(doc, resource)](){:title="org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(Document, Resource)"} => [documentReader.registerBeanDefinitions(doc, createReaderContext(resource))](){:title="org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(Document, XmlReaderContext)"} => [doRegisterBeanDefinitions(root)](){:title="org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(Element)"} => [parseBeanDefinitions(root, this.delegate)](){:title="org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(Element, BeanDefinitionParserDelegate)"} => [BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry())](){:title="org.springframework.beans.factory.support.BeanDefinitionReaderUtils.registerBeanDefinition(BeanDefinitionHolder, BeanDefinitionRegistry)"} => **载入结束** - 向IOC容器注册BeanDefinition的过程紧接着BeanDefinition载入的最后一步 [BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry())](){:title="org.springframework.beans.factory.support.BeanDefinitionReaderUtils.registerBeanDefinition(BeanDefinitionHolder, BeanDefinitionRegistry)"} => [registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition())](){:title="org.springframework.beans.factory.support.DefaultListableBeanFactory.registerBeanDefinition(String, BeanDefinition)"} bean在经过一系列检验成功后，注册进[beanDefinitionMap](){:title="this.beanDefinitionMap.put(beanName, beanDefinition);"} **说明：** - 初始化过程中，通过refresh()启动整个调用 - 使用的IOC容器为[DefaultListableBeanFactory](){:title="org.springframework.beans.factory.support.DefaultListableBeanFactory"} - 具体的资源载入是在[XmlBeanDefinitionReader](){:title="org.springframework.beans.factory.xml.XmlBeanDefinitionReader"} 读入BeanDefinition时完成，在其基类[AbstractBeanDefinitionReader](){:title="org.springframework.beans.factory.support.AbstractBeanDefinitionReader"}中可看到。 - 载入过程的启动，可以在[AbstractBeanDefinitionReader](){:title="org.springframework.beans.factory.support.AbstractBeanDefinitionReader"}中的`loadBeanDefinitions(String... locations)`中看到 - 解析BeanDefinition，使用了[BeanDefinitionParserDelegate](){:title="org.springframework.beans.factory.xml.BeanDefinitionParserDelegate"} - 解析成功的BeanDefinition，最终存入[beanDefinitionMap](){:title="org.springframework.beans.factory.support.DefaultListableBeanFactory.beanDefinitionMap"}中，类型为`java.util.concurrent.ConcurrentHashMap`。 ## 2.refresh()步骤 **待添加refresh每一步详细笔记** ### 2.1.**prepareRefresh** 准备context refresh的环境 - 设置开始时间为当前时间； - 设置active的标识为true； - 初始化属性源（加载属性文件，并将 placeholders 替换为配置文件中的属性源）-调用子类方法 ```JAVA initPropertySources(); getEnvironment().validateRequiredProperties(); ``` ### 2.2.**obtainFreshBeanFactory** 通知子类刷新内部beanFactory并返回刷新后的beanFactory - 刷新beanFactory ```java refreshBeanFactory(); ``` bean存在，就销毁bean； bean不存在，就创建bean(org.springframework.beans.factory.support.DefaultListableBeanFactory)，并加载BeanDefinition - 获取刷新后的beanFactory（同步方法synchronized） ```java ConfigurableListableBeanFactory beanFactory = getBeanFactory(); ``` ### 2.3.**prepareBeanFactory** 准备context使用的Beanfactory,即上一步成功刷新并获取的Beanfactory - 通知内部Beanfactory使用context的类加载器等 ```java beanFactory.setBeanClassLoader(getClassLoader()); beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader())); beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment())); ``` - 配置Beanfactory的context回调 ```java beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this)); beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class); beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class); beanFactory.ignoreDependencyInterface(MessageSourceAware.class); beanFactory.ignoreDependencyInterface(ApplicationContextAware.class); beanFactory.ignoreDependencyInterface(EnvironmentAware.class); ``` - MessageSource注册为bean；普通工厂中Beanfactory接口不注册为解析类型 ```java beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory); beanFactory.registerResolvableDependency(ResourceLoader.class, this); beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this); beanFactory.registerResolvableDependency(ApplicationContext.class, this); ``` - 检测LoadTimeWeaver的beanName是否存在 ```java if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) { beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory)); // Set a temporary ClassLoader for type matching. beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader())); } ``` - 注册默认的环境bean ```java if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) { beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment()); } if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) { beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties()); } if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) { beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment()); } ``` ### 2.4.**postProcessBeanFactory**：对上下文子类中的beanfactory进行后置处理修改已经标准初始化完成的ApplicationContext内部Beanfactory。此时所有的BeanDefinition将会被加载，但没有bean将被实例化。允许注册指定的`BeanPostProcessors`等 - 寄存器请求会话范围 ```java beanFactory.addBeanPostProcessor(new ServletContextAwareProcessor(this.servletContext, this.servletConfig)); beanFactory.ignoreDependencyInterface(ServletContextAware.class); beanFactory.ignoreDependencyInterface(ServletConfigAware.class); WebApplicationContextUtils.registerWebApplicationScopes(beanFactory, this.servletContext); WebApplicationContextUtils.registerEnvironmentBeans(beanFactory, this.servletContext, this.servletConfig); ``` 注册web application Context的范围注册环境bean ("servletContext", "contextParameters", "contextAttributes") ### 2.5.**invokeBeanFactoryPostProcessors** 依据指定的顺序，实例化并调用已经注册为beans的BeanFactoryPostProcessor。必须在单例实例化之前调用 ### 2.6.**registerBeanPostProcessors** 依据指定的顺序，实例化并调用已经注册为beans的BeanFactoryPostProcessor。必须在任何application的beans实例化之前调用 ### 2.7.**initMessageSource** 初始化消息源 ### 2.8.**initApplicationEventMulticaster** 初始化context的事件多路广播，注册为单例bean ### 2.9.**onRefresh** 初始化主题能力 ```java this.themeSource = UiApplicationContextUtils.initThemeSource(this); ``` ### 2.10.**registerListeners** 将实现了ApplicationListener接口的bean注册为监听器 - 首先注册静态指定的监听器 - 发布早期应用事件现在我们终于有了一个多路广播 ### 2.11.**finishBeanFactoryInitialization** - 实例化context的BeanFactory - 实例化所有的非懒加载的单例bean ### 2.12.**finishRefresh** - 初始化context的生命周期处理器 - 首先刷新context的生命周期处理器 - 发送最终的刷新事件 - 如果已经激活，将context注册进LiveBeansView ### 2.13.**resetCommonCaches** 重置Spring公共缓存 ```java ReflectionUtils.clearCache(); ResolvableType.clearCache(); CachedIntrospectionResults.clearClassLoader(getClassLoader()); ``` ### 总结：初始化过程主要完成了在IOC容器中建立BeanDefinition的数据映射，并没有IOC容器对Bean的依赖关系进行注入。 **下一篇的[Spring源码阅读笔记（2）]({% post_url 2016-05-11-spring-sources-read-2 %}){:title="IOC容器的依赖注入" :target="_blank"}中将会详细讲解**