SpringSecurity6从入门到上天系列第七篇：讲明白SpringBoot的自动装配完善上篇文章中的结论

文章目录

一：SpringBoot的自动装配

1：从run方法到入口类内容被注册到注解解读器中。

2：解析入口类注解到加载Bean实例

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本专栏简介：话不多说，让我们一起干翻SpringSecurity6

本文章简介：话不多说，让我们讲清楚SpringSecurity6中为什么在引入SpringSecurity之后所有的请求都需要先做登录认证才可以进行访问呢

一：SpringBoot的自动装配

1：从run方法到入口类内容被注册到注解解读器中。

    public static void main(String[] args) {SpringApplication.run(AlibabaApplication.class, args);}

       然后走到了一个run方法：

	public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) {return new SpringApplication(primarySources).run(args);}

        查看这里边的构造器方法：

	public SpringApplication(Class<?>... primarySources) {this(null, primarySources);}public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {this.resourceLoader = resourceLoader;Assert.notNull(primarySources, "PrimarySources must not be null");this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));this.webApplicationType = WebApplicationType.deduceFromClasspath();this.bootstrapRegistryInitializers = new ArrayList<>(getSpringFactoriesInstances(BootstrapRegistryInitializer.class));setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));this.mainApplicationClass = deduceMainApplicationClass();}

        随后，我们查看具体的run方法：

	public ConfigurableApplicationContext run(String... args) {long startTime = System.nanoTime();DefaultBootstrapContext bootstrapContext = createBootstrapContext();ConfigurableApplicationContext context = null;configureHeadlessProperty();SpringApplicationRunListeners listeners = getRunListeners(args);listeners.starting(bootstrapContext, this.mainApplicationClass);try {ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);ConfigurableEnvironment environment = prepareEnvironment(listeners, bootstrapContext, applicationArguments);Banner printedBanner = printBanner(environment);context = createApplicationContext();context.setApplicationStartup(this.applicationStartup);//准备解析工作prepareContext(bootstrapContext, context, environment, listeners, applicationArguments, printedBanner);//真正的解析工作refreshContext(context);afterRefresh(context, applicationArguments);Duration timeTakenToStartup = Duration.ofNanos(System.nanoTime() - startTime);if (this.logStartupInfo) {new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), timeTakenToStartup);}listeners.started(context, timeTakenToStartup);callRunners(context, applicationArguments);}catch (Throwable ex) {if (ex instanceof AbandonedRunException) {throw ex;}handleRunFailure(context, ex, listeners);throw new IllegalStateException(ex);}try {if (context.isRunning()) {Duration timeTakenToReady = Duration.ofNanos(System.nanoTime() - startTime);listeners.ready(context, timeTakenToReady);}}catch (Throwable ex) {if (ex instanceof AbandonedRunException) {throw ex;}handleRunFailure(context, ex, null);throw new IllegalStateException(ex);}return context;}

我们查看准备工作：

	private void prepareContext(DefaultBootstrapContext bootstrapContext, ConfigurableApplicationContext context,ConfigurableEnvironment environment, SpringApplicationRunListeners listeners,ApplicationArguments applicationArguments, Banner printedBanner) {context.setEnvironment(environment);postProcessApplicationContext(context);addAotGeneratedInitializerIfNecessary(this.initializers);applyInitializers(context);listeners.contextPrepared(context);bootstrapContext.close(context);if (this.logStartupInfo) {logStartupInfo(context.getParent() == null);logStartupProfileInfo(context);}// Add boot specific singleton beansConfigurableListableBeanFactory beanFactory = context.getBeanFactory();beanFactory.registerSingleton("springApplicationArguments", applicationArguments);if (printedBanner != null) {beanFactory.registerSingleton("springBootBanner", printedBanner);}if (beanFactory instanceof AbstractAutowireCapableBeanFactory autowireCapableBeanFactory) {autowireCapableBeanFactory.setAllowCircularReferences(this.allowCircularReferences);if (beanFactory instanceof DefaultListableBeanFactory listableBeanFactory) {listableBeanFactory.setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);}}if (this.lazyInitialization) {context.addBeanFactoryPostProcessor(new LazyInitializationBeanFactoryPostProcessor());}context.addBeanFactoryPostProcessor(new PropertySourceOrderingBeanFactoryPostProcessor(context));if (!AotDetector.useGeneratedArtifacts()) {// Load the sourcesSet<Object> sources = getAllSources();Assert.notEmpty(sources, "Sources must not be empty");load(context, sources.toArray(new Object[0]));}listeners.contextLoaded(context);}

        getAllSources获取入口类的信息。放到sources这个Set集合里边，然后去做load，我们查看load方法。

	protected void load(ApplicationContext context, Object[] sources) {if (logger.isDebugEnabled()) {logger.debug("Loading source " + StringUtils.arrayToCommaDelimitedString(sources));}BeanDefinitionLoader loader = createBeanDefinitionLoader(getBeanDefinitionRegistry(context), sources);if (this.beanNameGenerator != null) {loader.setBeanNameGenerator(this.beanNameGenerator);}if (this.resourceLoader != null) {loader.setResourceLoader(this.resourceLoader);}if (this.environment != null) {loader.setEnvironment(this.environment);}loader.load();}void load() {for (Object source : this.sources) {load(source);}}private void load(Object source) {Assert.notNull(source, "Source must not be null");if (source instanceof Class<?> clazz) {load(clazz);return;}if (source instanceof Resource resource) {load(resource);return;}if (source instanceof Package pack) {load(pack);return;}if (source instanceof CharSequence sequence) {load(sequence);return;}throw new IllegalArgumentException("Invalid source type " + source.getClass());}private void load(Class<?> source) {if (isGroovyPresent() && GroovyBeanDefinitionSource.class.isAssignableFrom(source)) {// Any GroovyLoaders added in beans{} DSL can contribute beans hereGroovyBeanDefinitionSource loader = BeanUtils.instantiateClass(source, GroovyBeanDefinitionSource.class);((GroovyBeanDefinitionReader) this.groovyReader).beans(loader.getBeans());}if (isEligible(source)) {this.annotatedReader.register(source);}}

        到这里完成了一个重要的工作：读取入口类中重要的信息，包括注解包括入口类本身。将入口类中的注解注册到注解解读器annotationreader当中。

2：解析入口类注解到加载Bean

        真正解析Bean的工作是从refreshContext当中进行的。

	private void refreshContext(ConfigurableApplicationContext context) {if (this.registerShutdownHook) {shutdownHook.registerApplicationContext(context);}refresh(context);}protected void refresh(ConfigurableApplicationContext applicationContext) {applicationContext.refresh();}

           最后跑到了一个applicationContext的refresh方法当中。

	@Overridepublic void refresh() throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {StartupStep contextRefresh = this.applicationStartup.start("spring.context.refresh");// Prepare this context for refreshing.prepareRefresh();// Tell the subclass to refresh the internal bean factory.ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();// Prepare the bean factory for use in this context.prepareBeanFactory(beanFactory);try {// Allows post-processing of the bean factory in context subclasses.postProcessBeanFactory(beanFactory);StartupStep beanPostProcess = this.applicationStartup.start("spring.context.beans.post-process");// Invoke factory processors registered as beans in the context.invokeBeanFactoryPostProcessors(beanFactory);// Register bean processors that intercept bean creation.registerBeanPostProcessors(beanFactory);beanPostProcess.end();// 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) {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();contextRefresh.end();}}}

接下来会进行Bean处理的13方法，其中一个比较关键的方法：invokeBeanFactoryPostProcessors

	protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());// Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime// (e.g. through an @Bean method registered by ConfigurationClassPostProcessor)if (!NativeDetector.inNativeImage() && beanFactory.getTempClassLoader() == null &&beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));}}

        这里边会对我们的入口类中的注解进行详细的解析和复杂调用。其中对这些注解进行解析的时候，要用到了这么一个类：AutoConfigurationImportSelector

        我们可以从调用链路上去证明这件事情：

"main@1" prio=5 tid=0x1 nid=NA runnablejava.lang.Thread.State: RUNNABLEat org.springframework.boot.context.annotation.ImportCandidates.load(ImportCandidates.java:90)at org.springframework.boot.autoconfigure.AutoConfigurationImportSelector.getCandidateConfigurations(AutoConfigurationImportSelector.java:180)at org.springframework.boot.autoconfigure.AutoConfigurationImportSelector.getAutoConfigurationEntry(AutoConfigurationImportSelector.java:126)at org.springframework.boot.autoconfigure.AutoConfigurationImportSelector$AutoConfigurationGroup.process(AutoConfigurationImportSelector.java:430)at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorGrouping.getImports(ConfigurationClassParser.java:796)at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorGroupingHandler.processGroupImports(ConfigurationClassParser.java:726)at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorHandler.process(ConfigurationClassParser.java:697)at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:182)at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:415)at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:287)at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:344)at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:115)at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:779)at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:597)- locked <0x12a7> (a java.lang.Object)at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:146)at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:733)at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:435)at org.springframework.boot.SpringApplication.run(SpringApplication.java:311)at org.springframework.boot.SpringApplication.run(SpringApplication.java:1301)at org.springframework.boot.SpringApplication.run(SpringApplication.java:1290)at com.dashu.AlibabaApplication.main(AlibabaApplication.java:10)

        所以，这个在自动装配的过程当中，确实完成了SpringSecurity的自动加载和配置。