我们分析了下面这个run方法的前半部分，本篇文章继续开工
public ConfigurableApplicationContext run(String… args) { //。。。 //接上文继续 configureIgnoreBeanInfo(environment); Banner printedBanner = printBanner(environment); context= createApplicationContext(); exceptionReporters = getSpringFactoriesInstances( SpringBootExceptionReporter.class, newClass[] { ConfigurableApplicationContext.class},context); prepareContext(context, environment, listeners, applicationArguments, printedBanner); refreshContext(context); afterRefresh(context, applicationArguments); stopWatch.stop(); if(this.logStartupInfo) { newStartupInfoLogger(this.mainApplicationClass) .logStarted(getApplicationLog(), stopWatch); } listeners.started(context); callRunners(context, applicationArguments); } catch (Throwable ex) { handleRunFailure(context, listeners, exceptionReporters, ex); thrownewIllegalStateException(ex); } listeners.running(context); returncontext; }
- 获取系统属性spring.beaninfo.ignore
privatevoidconfigureIgnoreBeanInfo(ConfigurableEnvironment environment) { if(System.getProperty( CachedIntrospectionResults.”spring.beaninfo.ignore”) ==null) { Booleanignore = environment.getProperty(“spring.beaninfo.ignore”, Boolean.class,Boolean.TRUE); System.setProperty(CachedIntrospectionResults.”spring.beaninfo.ignore”, ignore.toString()); } }
但是这个属性的作用还真不知道。。
- 打印banner
- 根据当前环境创建ApplicationContext
protected ConfigurableApplicationContext createApplicationContext() { Class<?> contextClass =this.applicationContextClass; if(contextClass ==null) { try{ switch(this.webApplicationType) { caseSERVLET: contextClass = Class.forName(DEFAULT_WEB_CONTEXT_CLASS); break; caseREACTIVE: contextClass = Class.forName(DEFAULT_REACTIVE_WEB_CONTEXT_CLASS); break; default: contextClass = Class.forName(DEFAULT_CONTEXT_CLASS); } } catch(ClassNotFoundException ex) { thrownewIllegalStateException( “Unable create a default ApplicationContext, ” +”please specify an ApplicationContextClass”, ex); } } return(ConfigurableApplicationContext) BeanUtils.instantiateClass(contextClass); }
基于咱们的Servlet环境，所以创建的ApplicationContext为AnnotationConfigServletWebServerApplicationContext
- 加载SpringBootExceptionReporter，这个类里包含了SpringBoot启动失败后异常处理相关的组件
private<T>Collection<T> getSpringFactoriesInstances(Class<T> type, Class<?>[] parameterTypes,Object… args) { ClassLoaderclassLoader =Thread.currentThread().getContextClassLoader(); Set<String> names =newLinkedHashSet<>( SpringFactoriesLoader.loadFactoryNames(type, classLoader)); List<T> instances = createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names); AnnotationAwareOrderComparator.sort(instances); returninstances; }
10 prepareContext 这一块还是比较长的
privatevoidprepareContext(ConfigurableApplicationContextcontext, ConfigurableEnvironment environment, SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) { context.setEnvironment(environment); postProcessApplicationContext(context); applyInitializers(context); listeners.contextPrepared(context); if(this.logStartupInfo) { logStartupInfo(context.getParent() ==null); logStartupProfileInfo(context); } context.getBeanFactory().registerSingleton(“springApplicationArguments”, applicationArguments); if(printedBanner !=null) { context.getBeanFactory().registerSingleton(“springBootBanner”, printedBanner); } // Load the sources Set<Object> sources = getAllSources(); Assert.notEmpty(sources,”Sources must not be empty”); load(context, sources.toArray(newObject[0])); listeners.contextLoaded(context);}1.第一行，将context中相关的environment全部替换public void setEnvironment(ConfigurableEnvironment environment) { super.setEnvironment(environment); // 设置context的environment this.reader.setEnvironment(environment); // 实例化context的reader属性的conditionEvaluator属性 this.scanner.setEnvironment(environment); // 设置context的scanner属性的environment属性}2.上下文后处理protectedvoidpostProcessApplicationContext(ConfigurableApplicationContextcontext) { if(this.beanNameGenerator!=null) { context.getBeanFactory().registerSingleton( AnnotationConfigUtils.CONFIGURATION_BEAN_NAME_GENERATOR, this.beanNameGenerator); } if(this.resourceLoader!=null) { if(contextinstanceof GenericApplicationContext) { ((GenericApplicationContext)context) .setResourceLoader(this.resourceLoader); } if(contextinstanceof DefaultResourceLoader) { ((DefaultResourceLoader)context) .setClassLoader(this.resourceLoader.getClassLoader()); } }}
这一块默认beanNameGenerator和resourceLoader都是空的，只有当我们自定义这两个对象时才会把容器内的bean替换
3. 执行所有的ApplicationContextInitializer的initialize方法
protectedvoidapplyInitializers(ConfigurableApplicationContextcontext) { for(ApplicationContextInitializer initializer : getInitializers()) { Class<?> requiredType = GenericTypeResolver.resolveTypeArgument( initializer.getClass(), ApplicationContextInitializer.class); Assert.isInstanceOf(requiredType,context,”Unable to call initializer.”); initializer.initialize(context); }}4.`listeners.contextPrepared(context)`这是个空方法，没有实现，一个Spring的扩展点5.打印profile6.注册bean：`springApplicationArguments`7.发布事件publicvoidcontextLoaded(ConfigurableApplicationContextcontext) { for(ApplicationListener<?> listener :this.application.getListeners()) { if(listener instanceof ApplicationContextAware) { ((ApplicationContextAware) listener).setApplicationContext(context); } context.addApplicationListener(listener); } this.initialMulticaster.multicastEvent( newApplicationPreparedEvent(this.application,this.args,context)); }
这里不仅发布了ApplicationPreparedEvent事件，还往实现了ApplicationContextAware接口的监听器中注入了context容器
8. load，其实就是创建了一个BeanDefinitionLoader对象
protectedvoidload(ApplicationContextcontext, 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(); }
- 容器的初始化refreshContext
这个方法最后还是调用的AbstractApplicationContext类的refresh方法，由于篇幅过长这里就不展开了，感兴趣的同学可以参考这篇文章：基于注解的SpringIOC源码解析
public void refresh() throws BeansException, IllegalStateException { synchronized(this.startupShutdownMonitor) { // 记录容器的启动时间、标记“已启动”状态、检查环境变量 prepareRefresh(); // 初始化BeanFactory容器、注册BeanDefinition ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory(); // 设置 BeanFactory 的类加载器，添加几个 BeanPostProcessor，手动注册几个特殊的 bean prepareBeanFactory(beanFactory); try{ // 扩展点 postProcessBeanFactory(beanFactory); // 调用 BeanFactoryPostProcessor 各个实现类的 postProcessBeanFactory(factory) 方法 invokeBeanFactoryPostProcessors(beanFactory); // 注册 BeanPostProcessor 的实现类 registerBeanPostProcessors(beanFactory); // 初始化MessageSource initMessageSource(); // 初始化事件广播器 initApplicationEventMulticaster(); // 扩展点 onRefresh(); // 注册事件监听器 registerListeners(); // 初始化所有的 singleton beans finishBeanFactoryInitialization(beanFactory); // 广播事件 finishRefresh(); } catch(BeansException ex) { if(logger.isWarnEnabled()) { logger.warn(“Exception encountered during context initialization – “+ “cancelling refresh attempt: “+ ex); } // 销毁已经初始化的的Bean destroyBeans(); // 设置 ‘active’ 状态 cancelRefresh(ex); throwex; } finally{ // 清除缓存 resetCommonCaches(); } }}
- afterRefresh
这里没有任何实现，Spring留给我们的扩展点 - 停止之前启动的计时装置，然后发送ApplicationStartedEvent事件
- 调用系统中ApplicationRunner以及CommandLineRunner接口的实现类，关于这两个接口的使用可以参考我的这篇文章：Java项目启动时执行指定方法的几种方式
privatevoidcallRunners(ApplicationContext context, ApplicationArguments args) { List<Object> runners =newArrayList<>(); runners.addAll(context.getBeansOfType(ApplicationRunner.class).values()); runners.addAll(context.getBeansOfType(CommandLineRunner.class).values()); AnnotationAwareOrderComparator.sort(runners); for(Objectrunner :newLinkedHashSet<>(runners)) { if(runnerinstanceofApplicationRunner) { callRunner((ApplicationRunner) runner, args); } if(runnerinstanceofCommandLineRunner) { callRunner((CommandLineRunner) runner, args); } } }
- 异常处理
- 发送ApplicationReadyEvent事件
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