第04节方法解析前3步

1、前言在spring boot 源码2 SpringApplication初始化 中我们分析SpringApplication的初始化 接下来我们继续分析SpringApplication的run方法1 SpringApplication#run方法的代码如下:该方法做13件事:初始化StopWatch 调用其start方法开始计时1调用configureHeadlessProperty设置系统属性java awt headless，这设置为true，表示运在服务端，在没有显示和鼠标键盘的模式，模拟输入输出功能2调用SpringApplicationRunListeners#starting3创

2、建一个DefaultApplicationArguments对象 它持有着args参数，就是main函数传进来的参数 调用prepareEnvironment方法4打印banner5创建SpringBoot上下文6初始化FailureAnalyzers7调用prepareContext8调用AbstractApplicationContext#refresh方法 并钩子9在容完成刷新后，依次调用的Runners10调用SpringApplicationRunListeners#finished11停止计时12初始化过程中出现异常时调用handleRunFailure进处 然后抛出 llegal

3、StateException异常13public ConfigurableApplicationContext run(String. args) / 计时工具StopWatch stopWatch = new StopWatch(); stopWatch.start(); ConfigurableApplicationContext context = null; FailureAnalyzers analyzers = null; configureHeadlessProperty();SpringApplicationRunListeners listeners = getRunList

4、eners(args); listeners.starting();try / 创建一个DefaultApplicationArguments对象，它持有着args参数，就是main函数传进来的参数ApplicationArguments applicationArguments = new DefaultApplicationArguments( args);ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);Banner printedBanner = print

5、Banner(environment);/ 创建SpringBoot上下文context = createApplicationContext(); analyzers = new FailureAnalyzers(context);prepareContext(context, environment, listeners, applicationArguments, printedBanner);refreshContext(context); afterRefresh(context, applicationArguments); listeners.finished(context,

6、null); stopWatch.stop();if (this.logStartupInfo) new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);return context;catch (Throwable ex) handleRunFailure(context, listeners, analyzers, ex); throw new IllegalStateException(ex);run方法中第1步 代码如下:2在StopWatch初始化时 设置i

7、d为"" 代码如下:start方法代码如下:在start方法中 首先当前状态是否为running 如果是的话 抛出异常 如果是的话 将running设置为true currentTaskName设置为"" startTimeMillis为当前时间在run方法中的第12步中 调用StopWatch#stop方法 停止计码如下:还是同样的套 如果running为false > 抛出异常 如果是 则计算得出lastTime 初始化Task nfo 将Task nfo加入到taskList中 增加taskCount计数 将running设为false 将c

8、urrentTaskName置为nullrun方法第2步 > 调用configureHeadlessProperty方法 设置系统属性java awt headless，这设置为true，表示运在服务端，在没有显示和鼠标键盘的模式，模拟3输入输出功能 该方法如下:run方法第3步 代码如下:4getRunListeners方法如下:还是同样的味道 通过调用getSpringFactories nstances加载SpringApplicationRunListener 然后初始化SpringApplicationRunListenersprivate SpringApplicationR

9、unListeners getRunListeners(String args) Class<?> types = new Class<?> SpringApplication.class, String.class ; return new SpringApplicationRunListeners(logger, getSpringFactoriesInstances(SpringApplicationRunListener.class, types, this, args);SpringApplicationRunListeners listeners = get

10、RunListeners(args); listeners.starting();private void configureHeadlessProperty() System.setProperty(SYSTEM_PROPERTY_JAVA_AWT_HEADLESS, System.getProperty(SYSTEM_PROPERTY_JAVA_AWT_HEADLESS, Boolean.toString(this.headless);public void stop() throws IllegalStateException if (!this.running) throw new I

11、llegalStateException("Can't stop StopWatch: it's not running");long lastTime = System.currentTimeMillis() - this.startTimeMillis; this.totalTimeMillis += lastTime;this.lastTaskInfo = new TaskInfo(this.currentTaskName, lastTime); if (this.keepTaskList) this.taskList.add(lastTaskInfo

12、);+this.taskCount; this.running = false; this.currentTaskName = null;public void start() throws IllegalStateException start("");public void start(String taskName) throws IllegalStateException if (this.running) throw new IllegalStateException("Can't start StopWatch: it's alread

13、y running");this.running = true; this.currentTaskName = taskName;this.startTimeMillis = System.currentTimeMillis();public StopWatch() this("");public StopWatch(String id) this.id = id;StopWatch stopWatch = new StopWatch(); stopWatch.start();对应当前场景来说 org springframework boot SpringAppl

14、icationRunListener只有一个(配置在META NF/spring factories中) 如下:在初始化EventPublishingRunListener时 会将SpringApplication中的Listeners添加到EventPublishingRunListener中的initialMulticaster 代码如下:也就是在META-INF/spring.factories中配置的org.springframework.context.ApplicationListener.关于这点,我们在上节课中讲过.然后调用SpringApplicationRunListene

15、rs#starting方法 代码如下:由于只有一个 因此会调用EventPublishingRunListener的starting方法 代码如下:接着调用SimpleApplicationEventMulticaster#multicastEvent 代码如下:resolveDefaultEventType方法如下:调用:由于当前传入的ApplicationStartedEvent是ResolvableTypeProvider的实 因此最终会调用ResolvableType#forClass 代码如下:直接初始化ResolvableType 其构造如下:public static Resol

16、vableType forClass(Class<?> clazz) return new ResolvableType(clazz);public static ResolvableType forInstance(Object instance) Assert.notNull(instance, "Instance must not be null"); if (instance instanceof ResolvableTypeProvider) ResolvableType type = (ResolvableTypeProvider) instance

17、).getResolvableType(); if (type != null) return type;return ResolvableType.forClass(instance.getClass();private ResolvableType resolveDefaultEventType(ApplicationEvent event) return ResolvableType.forInstance(event);public void multicastEvent(ApplicationEvent event) multicastEvent(event, resolveDefa

18、ultEventType(event);public void starting() this.initialMulticaster.multicastEvent(new ApplicationStartedEvent(this.application, this.args);public void starting() for (SpringApplicationRunListener listener : this.listeners) listener.starting();public EventPublishingRunListener(SpringApplication appli

19、cation, String args) this.application = application;this.args = args;this.initialMulticaster = new SimpleApplicationEventMulticaster(); for (ApplicationListener<?> listener : application.getListeners() this.initialMulticaster.addApplicationListener(listener);org.springframework.boot.SpringAppl

20、icationRunListener= org.springframework.boot.context.event.EventPublishingRunListener实现回到SimpleApplicationEventMulticaster#multicastEvent中 此时会调用该方法调用getApplicationListeners获得ApplicationListener 然后调用SimpleApplicationEventMulticaster#invokeListener方法getApplicationListeners代码如下:该方法首先构建ListenerCacheKey

21、然后缓存中是否有的话 直接返回 否则调用retrieveApplicationListeners方法 如果this beanClassLoader = null | (ClassUtils isCacheSafe(event getClass() this beanClassLoader) && (sourceType = null | ClassUtils isCacheSafe(sourceTypethis beanClassLoader) 为真的话 则调用retrieveApplicationListeners方法时会进加锁 并将方法的返回值加入缓存 一般都会放入缓存的r

22、etrieveApplicationListeners方法 代码如下:protected Collection<ApplicationListener<?>> getApplicationListeners( ApplicationEvent event, ResolvableType eventType) Object source = event.getSource();Class<?> sourceType = (source != null ? source.getClass() : null);/ 1. 构造ListenerCacheKeyList

23、enerCacheKey cacheKey = new ListenerCacheKey(eventType, sourceType);/ Quick check for existing entry on ConcurrentHashMap./ 2. 如果retrieverCache中有的话,直接返回ListenerRetriever retriever = this.retrieverCache.get(cacheKey); if (retriever != null) return retriever.getApplicationListeners();if (this.beanClas

24、sLoader = null | (ClassUtils.isCacheSafe(event.getClass(), this.beanClassLoader) &&(sourceType = null | ClassUtils.isCacheSafe(sourceType, this.beanClassLoader) / Fully synchronized building and caching of a ListenerRetriever synchronized (this.retrievalMutex) retriever = this.retrieverCache

25、.get(cacheKey); if (retriever != null) return retriever.getApplicationListeners();retriever = new ListenerRetriever(true); Collection<ApplicationListener<?>> listeners =retrieveApplicationListeners(eventType, sourceType, retriever); this.retrieverCache.put(cacheKey, retriever);return lis

26、teners;else / No ListenerRetriever caching -> no synchronization necessary return retrieveApplicationListeners(eventType, sourceType, null);public void multicastEvent(final ApplicationEvent event, ResolvableType eventType) ResolvableType type = (eventType != null ? eventType : resolveDefaultEvent

27、Type(event); for (final ApplicationListener<?> listener : getApplicationListeners(event, type) Executor executor = getTaskExecutor(); if (executor != null) executor.execute(new Runnable() Overridepublic void run() invokeListener(listener, event););else invokeListener(listener, event);private R

28、esolvableType(Class<?> clazz) this.resolved = (clazz != null ? clazz : Object.class); / ApplicationStartedEvent.class this.type = this.resolved; / ApplicationStartedEvent.classthis.typeProvider = null; this.variableResolver = null; ponentType = null; this.hash = null;处逻辑如下:1 初始化allListeners li

29、steners listenerBeans 对于当前场景来说 listeners 中的元素如下:listenerBeans中的元素为空2 遍历listeners listenerBeans 如果是否支持指定的则加入到allListeners3 排序对于当前场景ApplicationStartedEvent支持的listeners如下:SimpleApplicationEventMulticaster#invokeListener方法如下:org.springframework.boot.logging.LoggingApplicationListener, org.springframewor

30、k.boot.autoconfigure.BackgroundPreinitializer, org.springframework.boot.context.config.DelegatingApplicationListener, org.springframework.boot.liquibase.LiquibaseServiceLocatorApplicationListenerorg.springframework.boot.context.config.ConfigFileApplicationListener, org.springframework.boot.context.c

31、onfig.AnsiOutputApplicationListener, org.springframework.boot.logging.LoggingApplicationListener, org.springframework.boot.logging.ClasspathLoggingApplicationListener, org.springframework.boot.autoconfigure.BackgroundPreinitializer, org.springframework.boot.context.config.DelegatingApplicationListen

32、er, org.springframework.boot.builder.ParentContextCloserApplicationListener, org.springframework.boot.ClearCachesApplicationListener, org.springframework.boot.context.FileEncodingApplicationListener, org.springframework.boot.liquibase.LiquibaseServiceLocatorApplicationListenerprivate Collection<A

33、pplicationListener<?>> retrieveApplicationListeners( ResolvableType eventType, Class<?> sourceType, ListenerRetriever retriever) LinkedList<ApplicationListener<?>> allListeners = new LinkedList<ApplicationListener<?>>(); Set<ApplicationListener<?>>

34、listeners;Set<String> listenerBeans; synchronized (this.retrievalMutex) listeners = new LinkedHashSet<ApplicationListener<?>>(this.defaultRetriever.applicationListeners); listenerBeans = new LinkedHashSet<String>(this.defaultRetriever.applicationListenerBeans);for (Applicatio

35、nListener<?> listener : listeners) if (supportsEvent(listener, eventType, sourceType) if (retriever != null) retriever.applicationListeners.add(listener);allListeners.add(listener);if (!listenerBeans.isEmpty() BeanFactory beanFactory = getBeanFactory(); for (String listenerBeanName : listenerB

36、eans) try Class<?> listenerType = beanFactory.getType(listenerBeanName);if (listenerType = null | supportsEvent(listenerType, eventType) ApplicationListener<?> listener =beanFactory.getBean(listenerBeanName, ApplicationListener.class);if (!allListeners.contains(listener) && suppo

37、rtsEvent(listener, eventType, sourceType) if (retriever != null) retriever.applicationListenerBeans.add(listenerBeanName);allListeners.add(listener);catch (NoSuchBeanDefinitionException ex) / Singleton listener instance (without backing bean definition) disappeared -/ probably in the middle of the d

38、estruction phaseAnnotationAwareOrderComparator.sort(allListeners); return allListeners;该方法主要调用do nvokeListener 当ErrorHandler为null时 当调用do nvokeListener出现异常时 会交由ErrorHandler进处 对于当前 ErrorHandler为null 那么ErrorHandler么时候进设置呢?如下:do nvokeListener代码如下:private void doInvokeListener(ApplicationListener listener, ApplicationEvent event) try listener.onApplicationEvent(event);catch (ClassCastException ex) St