spring boot 2.0 源码分析(五)
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在上一篇文章中朋友全版分析了spring boot是怎么才能 才能 准备上下文环境的,今天朋友来看一下run函数剩余的内容。还是先把run函数贴出来:
/**
* Run the Spring application, creating and refreshing a new
* {@link ApplicationContext}.
* @param args the application arguments (usually passed from a Java main method)
* @return a running {@link ApplicationContext}
*/
public ConfigurableApplicationContext run(String... args) {
StopWatch stopWatch = new StopWatch();
stopWatch.start();
ConfigurableApplicationContext context = null;
Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
configureHeadlessProperty();
SpringApplicationRunListeners listeners = getRunListeners(args);
listeners.starting();
try {
ApplicationArguments applicationArguments = new DefaultApplicationArguments(
args);
ConfigurableEnvironment environment = prepareEnvironment(listeners,
applicationArguments);
configureIgnoreBeanInfo(environment);
Banner printedBanner = printBanner(environment);
context = createApplicationContext();
exceptionReporters = getSpringFactoriesInstances(
SpringBootExceptionReporter.class,
new Class[] { ConfigurableApplicationContext.class }, context);
prepareContext(context, environment, listeners, applicationArguments,
printedBanner);
refreshContext(context);
afterRefresh(context, applicationArguments);
stopWatch.stop();
if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass)
.logStarted(getApplicationLog(), stopWatch);
}
listeners.started(context);
callRunners(context, applicationArguments);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, listeners);
throw new IllegalStateException(ex);
}
try {
listeners.running(context);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, null);
throw new IllegalStateException(ex);
}
return context;
}
朋友接着往下看,来看一下this.refreshContext(context);函数,许多函数用于刷新上下文,跟踪到源码看一下:
private void refreshContext(ConfigurableApplicationContext context) {
refresh(context);
if (this.registerShutdownHook) {
try {
context.registerShutdownHook();
}
catch (AccessControlException ex) {
// Not allowed in some environments.
}
}
}
在refreshContext函数中,第一行调用了refresh(context);跳转了一下,下面的代码是注册了另有俩个
应用关闭的函数钩子。
先来看refresh(context);函数:
/**
* Refresh the underlying {@link ApplicationContext}.
* @param applicationContext the application context to refresh
*/
protected void refresh(ApplicationContext applicationContext) {
Assert.isInstanceOf(AbstractApplicationContext.class, applicationContext);
((AbstractApplicationContext) applicationContext).refresh();
}
通过代码跟踪分析发现,我我觉得是调用了AbstractApplicationContext中的refresh办法。
在ServletWebServerApplicationContext和ReactiveWebServerApplicationContext的refresh函数中都不
调用了super.refresh();
public void refresh() throws BeansException, IllegalStateException {
Object var1 = this.startupShutdownMonitor;
synchronized(this.startupShutdownMonitor) {
this.prepareRefresh();
ConfigurableListableBeanFactory beanFactory = this.obtainFreshBeanFactory();
this.prepareBeanFactory(beanFactory);
try {
this.postProcessBeanFactory(beanFactory);
this.invokeBeanFactoryPostProcessors(beanFactory);
this.registerBeanPostProcessors(beanFactory);
this.initMessageSource();
this.initApplicationEventMulticaster();
this.onRefresh();
this.registerListeners();
this.finishBeanFactoryInitialization(beanFactory);
this.finishRefresh();
} catch (BeansException var9) {
if(this.logger.isWarnEnabled()) {
this.logger.warn("Exception encountered during context initialization \
- cancelling refresh attempt: " + var9);
}
this.destroyBeans();
this.cancelRefresh(var9);
throw var9;
} finally {
this.resetCommonCaches();
}
}
}
在这段代码中朋友都前要看完,其是使用了上下文中的startupShutdownMonitor属性创建另有俩个 同步代码库来执行的刷新动作。首先是实验this.prepareRefresh();准备刷新上下文:
protected void prepareRefresh() {
this.startupDate = System.currentTimeMillis();
this.closed.set(false);
this.active.set(true);
if(this.logger.isInfoEnabled()) {
this.logger.info("Refreshing " + this);
}
this.initPropertySources();
this.getEnvironment().validateRequiredProperties();
this.earlyApplicationEvents = new LinkedHashSet();
}
接着获取了bean工厂可是,设置了许多bean工厂的环境:
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
beanFactory.setBeanClassLoader(this.getClassLoader());
beanFactory.setBeanExpressionResolver(
new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
beanFactory.addPropertyEditorRegistrar(
new ResourceEditorRegistrar(this, this.getEnvironment()));
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
beanFactory.registerResolvableDependency(ResourceLoader.class, this);
beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
beanFactory.registerResolvableDependency(ApplicationContext.class, this);
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
if(beanFactory.containsBean("loadTimeWeaver")) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
beanFactory.setTempClassLoader(
new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
if(!beanFactory.containsLocalBean("environment")) {
beanFactory.registerSingleton("environment", this.getEnvironment());
}
if(!beanFactory.containsLocalBean("systemProperties")) {
beanFactory.registerSingleton("systemProperties",
this.getEnvironment().getSystemProperties());
}
if(!beanFactory.containsLocalBean("systemEnvironment")) {
beanFactory.registerSingleton("systemEnvironment",
this.getEnvironment().getSystemEnvironment());
}
}
接下来是发送了另有俩个 bean工厂的处理信号,其中ServletWebServerApplicationContext中的实现是在bean工厂里加上了另有俩个 WebApplicationContextServletContextAwareProcessor处理器:
protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
beanFactory.addBeanPostProcessor(
new WebApplicationContextServletContextAwareProcessor(this));
beanFactory.ignoreDependencyInterface(ServletContextAware.class);
}
紧接着可是调用了这处理器,可是 注册到bean工厂。可是 可是分别调用了initMessageSource()和initApplicationEventMulticaster()用于初始化监听器和监听管理器:
protected void initMessageSource() {
ConfigurableListableBeanFactory beanFactory = this.getBeanFactory();
if(beanFactory.containsLocalBean("messageSource")) {
this.messageSource = (MessageSource)beanFactory
.getBean("messageSource", MessageSource.class);
if(this.parent != null && this.messageSource instanceof HierarchicalMessageSource) {
HierarchicalMessageSource dms = (HierarchicalMessageSource)this.messageSource;
if(dms.getParentMessageSource() == null) {
dms.setParentMessageSource(this.getInternalParentMessageSource());
}
}
if(this.logger.isDebugEnabled()) {
this.logger.debug("Using MessageSource [" + this.messageSource + "]");
}
} else {
DelegatingMessageSource dms1 = new DelegatingMessageSource();
dms1.setParentMessageSource(this.getInternalParentMessageSource());
this.messageSource = dms1;
beanFactory.registerSingleton("messageSource", this.messageSource);
if(this.logger.isDebugEnabled()) {
this.logger.debug("Unable to locate MessageSource with name
\'messageSource\': using default [" + this.messageSource + "]");
}
}
}
protected void initApplicationEventMulticaster() {
ConfigurableListableBeanFactory beanFactory = this.getBeanFactory();
if(beanFactory.containsLocalBean("applicationEventMulticaster")) {
this.applicationEventMulticaster = (ApplicationEventMulticaster)beanFactory
.getBean("applicationEventMulticaster", ApplicationEventMulticaster.class);
if(this.logger.isDebugEnabled()) {
this.logger.debug("Using ApplicationEventMulticaster [" +
this.applicationEventMulticaster + "]");
}
} else {
this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
beanFactory.registerSingleton("applicationEventMulticaster",
this.applicationEventMulticaster);
if(this.logger.isDebugEnabled()) {
this.logger.debug("Unable to locate ApplicationEventMulticaster with name
\'applicationEventMulticaster\':
using default [" + this.applicationEventMulticaster + "]");
}
}
}
在initMessageSource函数中会首先判断beanFactory工厂中是是不是可是处在messageSource,可是不处在就会为当前的messageSource创建另有俩个 新的DelegatingMessageSource。
initApplicationEventMulticaster的初始化办法跟initMessageSource差没有 来不要 ,这里不再多述。继续看run函数,接下来调用onRefresh()函数,许多函数可是发送另有俩个 刷新的事件,源码中并没有 具体的实现。接着放下看,this.registerListeners();把spring容器内的listener和beanfactory的listener都加上到广播器中:
protected void registerListeners() {
Iterator listenerBeanNames = this.getApplicationListeners().iterator();
while(listenerBeanNames.hasNext()) {
ApplicationListener earlyEventsToProcess = (ApplicationListener)listenerBeanNames.next();
this.getApplicationEventMulticaster().addApplicationListener(earlyEventsToProcess);
}
String[] var6 = this.getBeanNamesForType(ApplicationListener.class, true, false);
String[] var7 = var6;
int var3 = var6.length;
for(int earlyEvent = 0; earlyEvent < var3; ++earlyEvent) {
String listenerBeanName = var7[earlyEvent];
this.getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
}
Set var8 = this.earlyApplicationEvents;
this.earlyApplicationEvents = null;
if(var8 != null) {
Iterator var9 = var8.iterator();
while(var9.hasNext()) {
ApplicationEvent var10 = (ApplicationEvent)var9.next();
this.getApplicationEventMulticaster().multicastEvent(var10);
}
}
}
通过this.finishBeanFactoryInitialization(beanFactory);实例化BeanFactory 中可是被注册可是 没被实例化的所有实例。初始化的过程中各种BeanPostProcessor就可是开始生效了:
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
if(beanFactory.containsBean("conversionService") &&
beanFactory.isTypeMatch("conversionService", ConversionService.class)) {
beanFactory.setConversionService((ConversionService)beanFactory
.getBean("conversionService", ConversionService.class));
}
if(!beanFactory.hasEmbeddedValueResolver()) {
beanFactory.addEmbeddedValueResolver((strVal) -> {
return this.getEnvironment().resolvePlaceholders(strVal);
});
}
String[] weaverAwareNames = beanFactory
.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
String[] var3 = weaverAwareNames;
int var4 = weaverAwareNames.length;
for(int var5 = 0; var5 < var4; ++var5) {
String weaverAwareName = var3[var5];
this.getBean(weaverAwareName);
}
beanFactory.setTempClassLoader((ClassLoader)null);
beanFactory.freezeConfiguration();
beanFactory.preInstantiateSingletons();
}
接下来调用finishRefresh()函数用于完成刷新后的许多扫尾工作,包括产生的缓存、初始化生命周期处理器LifecycleProcessor,并调用其onRefresh()办法、发布事件、调用LiveBeansView的registerApplicationContext注册context。
protected void finishRefresh() {
this.clearResourceCaches();
this.initLifecycleProcessor();
this.getLifecycleProcessor().onRefresh();
this.publishEvent((ApplicationEvent)(new ContextRefreshedEvent(this)));
LiveBeansView.registerApplicationContext(this);
}
接着看run函数,在刷新完context后,调用了另有俩个 afterRefresh函数,许多函数前面可是说过了,是为了给ApplicationContext的子类留下的另有俩个 扩展点。
可是 调用了listeners.started(context);,把监听器设置成了可是启动的状态。最后调用了callRunners函数,获取所有的ApplicationRunner和CommandLineRunner可是 调用朋友的run办法:
private void callRunners(ApplicationContext context, ApplicationArguments args) {
List<Object> runners = new ArrayList<>();
runners.addAll(context.getBeansOfType(ApplicationRunner.class).values());
runners.addAll(context.getBeansOfType(CommandLineRunner.class).values());
AnnotationAwareOrderComparator.sort(runners);
for (Object runner : new LinkedHashSet<>(runners)) {
if (runner instanceof ApplicationRunner) {
callRunner((ApplicationRunner) runner, args);
}
if (runner instanceof CommandLineRunner) {
callRunner((CommandLineRunner) runner, args);
}
}
}
总结:spring boot 2.0在启动的可是,首先会调用SpringApplication的构造函数进行初始化,调用实例函数run,在run函数中,首先获取监听器,并设置成启动状态,上面准备环境prepareEnvironment,准备prepareContext上下文,刷新上下文refreshContext,最后调用callRunners来依次调用注册的Runner。