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This article introduces the relevant knowledge of "refresh detailed explanation of spring extension startup process". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Spring extension launch process-refreshXmlWebApplicationContext

In the spring-webmvc startup process, we did not explain the refresh process of wac in detail, but just mentioned it one by one.

Whether it is entered from ContextLoaderListener or Servlet's init method, it is inseparable from the initialization of spring as a whole. Only with the reading of bean, the loaded spring is incomplete. Spring still needs these extensions. To make spring more perfect, let's take a look at the entry first.

/ / ContextLoader.javaprotected void configureAndRefreshWebApplicationContext (ConfigurableWebApplicationContext wac, ServletContext sc) {/ /. Wac.refresh ();} protected void configureAndRefreshWebApplicationContext (ConfigurableWebApplicationContext wac) {/ /... Wac.refresh ();} refresh

The refresh function contains almost all the functionality provided by ApplicationContext, and the logic in this function is clear, so take a look.

Debugging can be entered directly from the class ClassPathXmlApplicationContext, and the constructor can directly enter this method and initialize the entire environment.

/ / AbstractApplicationContext.javapublic void refresh () throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {/ / Prepare this context for refreshing. / / context prepareRefresh () to be refreshed; / / Tell the subclass to refresh the internal bean factory. / / initialize BeanFactory and read xml file ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory (); / / Prepare the bean factory for use in this context. / / A pair of BeanFactory to fill prepareBeanFactory (beanFactory) with various functions; try {/ / Allows post-processing of the bean factory in context subclasses. / / subclass overrides do extra processing postProcessBeanFactory (beanFactory); / / Invoke factory processors registered as beans in the context. / / activate various BeanFactory processors invokeBeanFactoryPostProcessors (beanFactory); / / Register bean processors that intercept bean creation. / / register to intercept the Bean processor created by Bean. Here is just registration. The call is registerBeanPostProcessors (beanFactory) when getBean is called; / / Initialize message source for this context. / / initialize the Message source for the context, that is, the message body of different languages, internationalize the process initMessageSource (); / / Initialize event multicaster for this context. / / initialize the application message broadcaster and put initApplicationEventMulticaster () in the "ApplicationEventMulticaster" Bean; / / Initialize other special beans in specific context subclasses. / / leave the subclass to initialize other Bean onRefresh (); / / Check for listener beans and register them. / / find Listenter bean in all registered Bean and register registerListeners () in the message broadcaster; / / Instantiate all remaining (non-lazy-init) singletons. / / initialize the remaining singleton (non-lazy) finishBeanFactoryInitialization (beanFactory); / / Last step: publish corresponding event. / / complete the refresh process, notify the lifecycle processor lifecycleProcessor to complete the refresh process, and issue ContextRefreshEvent to notify others of finishRefresh ();} catch (BeansException ex) {/ / Destroy already created singletons to avoid dangling resources. DestroyBeans (); / / Reset 'active' flag. CancelRefresh (ex); / / Propagate exception to caller. Throw ex;}} prepareRefresh//AbstractApplicationContext.javaprotected void prepareRefresh () {/ /... / / leave subclasses to override initPropertySources (); / / verify the properties file to ensure that all required files have been placed in the environment getEnvironment () .validateRequiredProperties (); / /...} obtainFreshBeanFactory

Initializing the BeanFactory, reading the xml file, starts from this place, using the default DefaultListableBeanFactory.

/ / AbstractApplicationContext.javaprotected ConfigurableListableBeanFactory obtainFreshBeanFactory () {/ / initialize BeanFactory refreshBeanFactory (); / / return the initialized BeanFactory return getBeanFactory ();} / / AbstractRefreshableApplicationContext.javaprotected final void refreshBeanFactory () throws BeansException {/ / check whether the initialized BeanFactory if (hasBeanFactory ()) {/ / destroy all bean destroyBeans (); / / close and destroy BeanFactory closeBeanFactory () } try {/ / create a default DefaultListableBeanFactory, and subclasses can override the method DefaultListableBeanFactory beanFactory = createBeanFactory (); beanFactory.setSerializationId (getId ()); / / Custom BeanFactory, including whether to allow overriding of different defined objects of the same name and circular dependency customizeBeanFactory (beanFactory); / / initialize XmlBeanDefinitionReader and parse the xml file. LoadBeanDefinitions (beanFactory); synchronized (this.beanFactoryMonitor) {this.beanFactory = beanFactory;}} catch (IOException ex) {...}} protected void customizeBeanFactory (DefaultListableBeanFactory beanFactory) {/ / set whether to allow bean with different definitions of the same name to override if (this.allowBeanDefinitionOverriding! = null) {beanFactory.setAllowBeanDefinitionOverriding (this.allowBeanDefinitionOverriding) } / / sets whether to allow circular dependency on if (this.allowCircularReferences! = null) {beanFactory.setAllowCircularReferences (this.allowCircularReferences);}} prepareBeanFactory

At this point, spring has completed the parsing of the configuration, and the functional extension of ApplicationContext has begun.

Protected void prepareBeanFactory (ConfigurableListableBeanFactory beanFactory) {beanFactory.setBeanClassLoader (getClassLoader ()); / / set expression language processor beanFactory.setBeanExpressionResolver (new StandardBeanExpressionResolver (beanFactory.getBeanClassLoader (); / / set a default property parser PropertyEditor beanFactory.addPropertyEditorRegistrar (new ResourceEditorRegistrar (this, getEnvironment (); / / add BeanPostProcessor beanFactory.addBeanPostProcessor (new ApplicationContextAwareProcessor (this)); / / set several interfaces beanFactory.ignoreDependencyInterface (EnvironmentAware.class) that ignore autoassembly BeanFactory.ignoreDependencyInterface (EmbeddedValueResolverAware.class); beanFactory.ignoreDependencyInterface (ResourceLoaderAware.class); beanFactory.ignoreDependencyInterface (ApplicationEventPublisherAware.class); beanFactory.ignoreDependencyInterface (MessageSourceAware.class); beanFactory.ignoreDependencyInterface (ApplicationContextAware.class); / / Registration depends on parsing, which is also the bean of spring, but it will be special. There will be interpretations beanFactory.registerResolvableDependency (BeanFactory.class, beanFactory); beanFactory.registerResolvableDependency (ResourceLoader.class, this); beanFactory.registerResolvableDependency (ApplicationEventPublisher.class, this). BeanFactory.registerResolvableDependency (ApplicationContext.class, this); / / add BeanPostProcessor beanFactory.addBeanPostProcessor (new ApplicationListenerDetector (this)); / / add support for AspectJ if (beanFactory.containsBean (LOAD_TIME_WEAVER_BEAN_NAME)) {beanFactory.addBeanPostProcessor (new LoadTimeWeaverAwareProcessor (beanFactory)); beanFactory.setTempClassLoader (new ContextTypeMatchClassLoader (beanFactory.getBeanClassLoader () } / / add the default system environment bean 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 ());}} main extension: 1. Increase the support for SPEL language; 2. Add support for the attribute editor, these PropertyEditors are only registered here, and when used, the bean is packaged as BeanWrapper, and the packaged BeanWrapper contains all these PropertyEditors for later use when setting properties to the bean; 3. Add information injection to some built-in classes (actually pre-processors), such as the Aware interface; 4. Set the interface that can be ignored by the dependent function; 5. Register some fixed bean, these are special dependency parsing, for example, when you register the dependency resolution of BeanFactory.class, when the attribute of bean is injected, once it is detected that the attribute is of BeanFactory type, the instance of beanFactory will be injected. 6. Increase support for AspectJ; 7. Register the relevant environment variables and attributes in singleton mode. InvokeBeanFactoryPostProcessors

Activate the registered BeanFactoryPostProcessor. This API is similar to BeanPostProcessor in that it can handle the definition of bean (configuration metadata). Its scope is container-level and only deals with the bean of its own container. Typical application PropertyPlaceholderConfigurer.

This part of the code is a little long, do not post, go and see for yourself.

RegisterBeanPostProcessors

Register all bean pre-and post-processor BeanPostProcessor, which is only registered here, and the call is made when the bean is created.

The code is also a little long, don't post it, go and see for yourself.

InitMessageSource

Internationalization processing, if you want to use custom, bean name is specified MESSAGE_SOURCE_BEAN_NAME = "messageSource".

Protected void initMessageSource () {ConfigurableListableBeanFactory beanFactory = getBeanFactory (); / / find messageSource according to the specified name. If a messageSource with the specified name is registered in the container, the registered if (beanFactory.containsLocalBean (MESSAGE_SOURCE_BEAN_NAME)) {this.messageSource = beanFactory.getBean (MESSAGE_SOURCE_BEAN_NAME, MessageSource.class) is used. If (this.parent! = null & & this.messageSource instanceof HierarchicalMessageSource) {HierarchicalMessageSource hms = (HierarchicalMessageSource) this.messageSource; if (hms.getParentMessageSource () = = null) {hms.setParentMessageSource (getInternalParentMessageSource ());}} / /. Log} else {/ / messageSource with the specified name is not registered in the container, using the default DelegatingMessageSource DelegatingMessageSource dms = new DelegatingMessageSource (); dms.setParentMessageSource (getInternalParentMessageSource ()); this.messageSource = dms; beanFactory.registerSingleton (MESSAGE_SOURCE_BEAN_NAME, this.messageSource); / /. Log}} initApplicationEventMulticaster

The event broadcaster that initializes the application is used for event listening. the logic is the same as initializing the internationalized MessageSource, but also has a specific name. If beanFactory is available, it is registered. If not, the default SimpleApplicationEventMulticaster is used.

The listener in the application is registered with this broadcaster and broadcast uniformly by the broadcaster.

RegisterListeners

Look for Listenter bean in all registered Bean and register with the message broadcaster.

Protected void registerListeners () {/ / first register statically registered listeners (code registered) for (ApplicationListener listener: getApplicationListeners ()) {getApplicationEventMulticaster () .addApplicationListener (listener);} / / get all configured listener in the container and register String [] listenerBeanNames = getBeanNamesForType (ApplicationListener.class, true, false); for (String listenerBeanName: listenerBeanNames) {getApplicationEventMulticaster () .addApplicationListenerBean (listenerBeanName) } / / A broadcast of these events on earlyApplicationEvents is actually traversing all the listener to find the listener processing that can handle event Set earlyEventsToProcess = this.earlyApplicationEvents; this.earlyApplicationEvents = null; if (earlyEventsToProcess! = null) {for (ApplicationEvent earlyEvent: earlyEventsToProcess) {getApplicationEventMulticaster (). MulticastEvent (earlyEvent);}} finishBeanFactoryInitialization

Initialize the remaining non-lazy singletons, and if a singleton relies on a lazy singleton, then the lazy singleton will also be initialized, which is easy to understand.

Protected void finishBeanFactoryInitialization (ConfigurableListableBeanFactory beanFactory) {/ / initializes ConversionService, similar to PropertyEditor 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)) } / / then register the default embedded value parser / / for example, PropertyPlaceholderConfigurer bean) previously registered: / / is mainly used for parsing annotated attribute values. If (! beanFactory.hasEmbeddedValueResolver ()) {beanFactory.addEmbeddedValueResolver (strVal-> getEnvironment (). ResolvePlaceholders (strVal));} / / initialize LoadTimeWeaverAware before singleton bean initialization to support aop,AspectJ String [] weaverAwareNames = beanFactory.getBeanNamesForType (LoadTimeWeaverAware.class, false, false); for (String weaverAwareName: weaverAwareNames) {getBean (weaverAwareName);} beanFactory.setTempClassLoader (null) / / freeze bean definitions (BeanDefinition), indicating that all bean definitions are not modified or further processed by beanFactory.freezeConfiguration (); / / initialize a non-lazy singleton, which actually traverses all beanName, and then calls getBean () beanFactory.preInstantiateSingletons () one by one;} finishRefreshprotected void finishRefresh () {/ / clears the resource cache at the context level (context-level), such as ASM metadata generated by scanning () / / initialize LifecycleProcessor initLifecycleProcessor (); / / use LifecycleProcessor to start the Lifecycle subclass getLifecycleProcessor (). OnRefresh (); / / context refresh completed, release event publishEvent (new ContextRefreshedEvent (this)); / / Participate in LiveBeansView MBean, if active. LiveBeansView.registerApplicationContext (this);}

When initializing LifecycleProcessor, just like initializing MessageResource, the default DefaultLifecycleProcessor is used if there is no customization.

GetLifecycleProcessor (). OnRefresh () will use our registered LyfecycleProcessor to start a subclass of our registered SmartLifeCycle. Take a look at the code.

/ / default DefaultLifecycleProcessor.javapublic void onRefresh () {startBeans (true); this.running = true;} private void startBeans (boolean autoStartupOnly) {/ / get all LifeCycle type bean Map lifecycleBeans = getLifecycleBeans (); Map phases = new HashMap () LifecycleBeans.forEach ((beanName, bean)-> {/ / default DefaultLifecycleProcessor only starts SmartLifecycle, or the non-automatic start type / / SmartLifecycle inherits Phases interface if (! autoStartupOnly | | (bean instanceof SmartLifecycle & ((SmartLifecycle) bean). IsAutoStartup ()) {int phase = getPhase (bean); LifecycleGroup group = phases.get (phase) If (group = = null) {group = new LifecycleGroup (phase, this.timeoutPerShutdownPhase, lifecycleBeans, autoStartupOnly); / / add phases.put (phase, group) to the collection to be started;} group.add (beanName, bean);}}) / / to start these LifeCycle if (! phases.isEmpty ()) {List keys = new ArrayList (phases.keySet ()); Collections.sort (keys); for (Integer key: keys) {phases.get (key). Start ();}} "spring extension startup process refresh detailed explanation" ends here, thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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