spring源码版本 5.1.5.RELEASE
ApplicationContext
- ApplicationContext和BeanFactory的关系?
- Spring 中 ApplicationContext是怎么启动? 具体子类?
- Spring web容器和Spring容器的关系?
- SpringBoot中 ApplicationContext是怎么启动? 具体子类?
基础容器接口
ApplicationContext
先来看看ApplicationContext接口的定义
public interface ApplicationContext extends EnvironmentCapable, ListableBeanFactory, HierarchicalBeanFactory,
MessageSource, ApplicationEventPublisher, ResourcePatternResolver {
...
}
ApplicationContext和BeanFactory的关系是? 从下面的接口定义中,
似乎就是简单的继承,除了BeanFactory相关的接口 还新增了
- ResourceLoader (资源加载)、 EnvironmentCapable (统称为资源管理)
- ApplicationEventPublisher (事件发布)
- MessageSource(国际化)
资源管理相关
Enviroment
@since 3.1 , 主要包含两部分 Profiles 和 properties
spring容器的初始化流程
- AbstractApplicationContext#getEnvironment
- AbstractRefreshableWebApplicationContext#createEnvironment
- AbstractRefreshableWebApplicationContext#customizePropertySources
- MutablePropertySources#addLast
更多细节:
@see org.springframework.core.env.PropertySource
PropertySources
MutablePropertySources
@see org.springframework.core.env.PropertyResolver
PropertySourcesPropertyResolver 完成 占位符的解析和类型转换
类型转换又是委托 ConversionService 完成的
@see org.springframework.context.support.PropertySourcesPlaceholderConfigurer
Bean 属性的占位符替换，需要注册 https://www.cnblogs.com/binarylei/p/8428211.html
扩展可参考: https://blog.csdn.net/zollty/article/details/86137826
在SpringBoot中是通过ConfigFileApplicationListener,加载相关
private void load(String location, String name, Profile profile,
DocumentFilterFactory filterFactory, DocumentConsumer consumer) {
if (!StringUtils.hasText(name)) {
for (PropertySourceLoader loader : this.propertySourceLoaders) {
if (canLoadFileExtension(loader, location)) {
load(loader, location, profile,
filterFactory.getDocumentFilter(profile), consumer);
return;
}
}
}
Set<String> processed = new HashSet<>();
for (PropertySourceLoader loader : this.propertySourceLoaders) {
for (String fileExtension : loader.getFileExtensions()) {
if (processed.add(fileExtension)) {
loadForFileExtension(loader, location + name, "." + fileExtension,
profile, filterFactory, consumer);
}
}
}
}
通过 org.springframework.boot.env.PropertySourceLoader 来加载
public interface PropertySourceLoader {
/**
* Returns the file extensions that the loader supports (excluding the '.').
* @return the file extensions
*/
String[] getFileExtensions();
/**
* Load the resource into one or more property sources. Implementations may either
* return a list containing a single source, or in the case of a multi-document format
* such as yaml a source for each document in the resource.
* @param name the root name of the property source. If multiple documents are loaded
* an additional suffix should be added to the name for each source loaded.
* @param resource the resource to load
* @return a list property sources
* @throws IOException if the source cannot be loaded
*/
List<PropertySource<?>> load(String name, Resource resource) throws IOException;
}
org.springframework.boot.env.PropertiesPropertySourceLoader
@Override
public List<PropertySource<?>> load(String name, Resource resource)
throws IOException {
Map<String, ?> properties = loadProperties(resource);
if (properties.isEmpty()) {
return Collections.emptyList();
}
return Collections
.singletonList(new OriginTrackedMapPropertySource(name, properties));
}
最后生成 OriginTrackedMapPropertySource
ResourceLoader
Resource接口有很多实现类，而ResourceLoader接口用于实现不同的Resource加载策略，即将不同Resource实例的创建交给ResourceLoader来计算。
BeanDefinitionReader
使用Resource加载BeanDefinition
public interface BeanDefinitionReader {
BeanDefinitionRegistry getRegistry();
@Nullable
ResourceLoader getResourceLoader();
@Nullable
ClassLoader getBeanClassLoader();
BeanNameGenerator getBeanNameGenerator();
//加载配置
int loadBeanDefinitions(Resource resource) throws BeanDefinitionStoreException;
int loadBeanDefinitions(Resource... resources) throws BeanDefinitionStoreException;
int loadBeanDefinitions(String location) throws BeanDefinitionStoreException;
int loadBeanDefinitions(String... locations) throws BeanDefinitionStoreException;
}
@Override
protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {
// 1. 创建 XmlBeanDefinitionReader
XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory);
// 2. 对 beanDefinitionReader 进行环境变量的设置
beanDefinitionReader.setEnvironment(this.getEnvironment());
beanDefinitionReader.setResourceLoader(this);
beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));
// 3. 对 beanDefinitionReader 进行设置，默认可以覆盖
initBeanDefinitionReader(beanDefinitionReader);
loadBeanDefinitions(beanDefinitionReader);
}
传统Spring中容器的启动流程
传统Spring启动方式
传统的Spring容器的启动流程, 是依托于Servlet容器 , Servlet容器初始化完后,通过注册监听器, 实现回调
通常在 WEB-INF/web.xml 下会有如下配置
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
在 org.springframework.web.context.ContextLoaderListener#contextInitialized 中
public void contextInitialized(ServletContextEvent event) {
this.contextLoader = createContextLoader();
if (this.contextLoader == null) {
this.contextLoader = this;
}
this.contextLoader.initWebApplicationContext(event.getServletContext());
}
传统Spring启动流程
/**
* Initialize Spring's web application context for the given servlet context,
* using the application context provided at construction time, or creating a new one
* according to the "{@link #CONTEXT_CLASS_PARAM contextClass}" and
* "{@link #CONFIG_LOCATION_PARAM contextConfigLocation}" context-params.
* @param servletContext current servlet context
* @return the new WebApplicationContext
* @see #ContextLoader(WebApplicationContext)
* @see #CONTEXT_CLASS_PARAM
* @see #CONFIG_LOCATION_PARAM
*/
public WebApplicationContext initWebApplicationContext(ServletContext servletContext) {
//重复初始化检查
if (servletContext.getAttribute(
WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE) != null) {
throw new IllegalStateException(
"Cannot initialize context because there is already a root application context present - check whether you have multiple ContextLoader* definitions in your web.xml!");
}
Log logger = LogFactory.getLog(ContextLoader.class);
long startTime = System.currentTimeMillis();
try {
// Store context in local instance variable, to guarantee that
// it is available on ServletContext shutdown.
//创建容器
if (this.context == null) {
this.context = createWebApplicationContext(servletContext);
}
if (this.context instanceof ConfigurableWebApplicationContext) {
ConfigurableWebApplicationContext cwac = (ConfigurableWebApplicationContext) this.context;
if (!cwac.isActive()) {
// The context has not yet been refreshed -> provide services such as
// setting the parent context, setting the application context id, etc
if (cwac.getParent() == null) {
// The context instance was injected without an explicit parent ->
// determine parent for root web application context, if any.
ApplicationContext parent = loadParentContext(servletContext);
cwac.setParent(parent);
}
//refresh操作
configureAndRefreshWebApplicationContext(cwac, servletContext);
}
}
servletContext.setAttribute(WebApplicationContext.
ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, this.context);
ClassLoader ccl = Thread.currentThread().getContextClassLoader();
if (ccl == ContextLoader.class.getClassLoader()) {
currentContext = this.context;
}
else if (ccl != null) {
currentContextPerThread.put(ccl, this.context);
}
return this.context;
}
catch (RuntimeException ex) {
logger.error("Context initialization failed", ex);
servletContext.setAttribute(WebApplicationContext.
ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, ex);
throw ex;
}
catch (Error err) {
logger.error("Context initialization failed", err);
servletContext.setAttribute(WebApplicationContext.
ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, err);
throw err;
}
}
ApplicationContext子类型
➡️ContextLoader#createWebApplicationContext(javax.servlet.ServletContext)
➡️ ContextLoader#determineContextClass
➡️ defaultStrategies.getProperty(WebApplicationContext.class.getName());
其中defaultStrategies的值在static中初始化了,DEFAULT_STRATEGIES_PATH的定义为ContextLoader.properties
static {
// Load default strategy implementations from properties file.
// This is currently strictly internal and not meant to be customized
// by application developers.
try {
ClassPathResource resource = new ClassPathResource(DEFAULT_STRATEGIES_PATH, ContextLoader.class);
defaultStrategies = PropertiesLoaderUtils.loadProperties(resource);
}
catch (IOException ex) {
throw new IllegalStateException("Could not load 'ContextLoader.properties': " + ex.getMessage());
}
}
在org/springframework/web/context/ContextLoader.properties路径下
# Default WebApplicationContext implementation class for ContextLoader.
# Used as fallback when no explicit context implementation has been specified as context-param.
# Not meant to be customized by application developers.
org.springframework.web.context.WebApplicationContext=org.springframework.web.context.support.XmlWebApplicationContext
所以我们的子类型就是XmlWebApplicationContext
XmlWebApplicationContext相关类分析
在XmlWebApplicationContext的doc中
/
* @see #setNamespace
* @see #setConfigLocations
* @see org.springframework.beans.factory.xml.XmlBeanDefinitionReader
* @see org.springframework.web.context.ContextLoader#initWebApplicationContext
* @see org.springframework.web.servlet.FrameworkServlet#initWebApplicationContext
*/
setConfigLocations
setConfigLocations 在web.xml中配置 , 用于获取目录
<!--Spring -->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>
classpath*:/config-spring/spring-*.xml
</param-value>
</context-param>
XmlBeanDefinitionReader
@Override
protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {
// Create a new XmlBeanDefinitionReader for the given BeanFactory.
XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory);
// Configure the bean definition reader with this context's
// resource loading environment.
beanDefinitionReader.setEnvironment(getEnvironment());
beanDefinitionReader.setResourceLoader(this);
beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));
// Allow a subclass to provide custom initialization of the reader,
// then proceed with actually loading the bean definitions.
initBeanDefinitionReader(beanDefinitionReader);
loadBeanDefinitions(beanDefinitionReader);
}
🌟ApplicationContext启动流程
关注refresh的部分,发现逻辑都在 AbstractApplicationContext
org.springframework.web.context.ContextLoader#configureAndRefreshWebApplicationContext
AbstractRefreshableWebApplicationContext(ConfigurableWebApplicationContext,servletContext相关)
➡️AbstractRefreshableConfigApplicationContext(setConfigLocation)
➡️AbstractRefreshableApplicationContext ( loadBeanDefinitions、refreshBeanFactory)
➡️AbstractApplicationContext
protected void configureAndRefreshWebApplicationContext(ConfigurableWebApplicationContext wac, ServletContext sc) {
if (ObjectUtils.identityToString(wac).equals(wac.getId())) {
// The application context id is still set to its original default value
// -> assign a more useful id based on available information
String idParam = sc.getInitParameter(CONTEXT_ID_PARAM);
if (idParam != null) {
wac.setId(idParam);
}
else {
// Generate default id...
wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX +
ObjectUtils.getDisplayString(sc.getContextPath()));
}
}
wac.setServletContext(sc);
String configLocationParam = sc.getInitParameter(CONFIG_LOCATION_PARAM);
if (configLocationParam != null) {
wac.setConfigLocation(configLocationParam);
}
// The wac environment's #initPropertySources will be called in any case when the context
// is refreshed; do it eagerly here to ensure servlet property sources are in place for
// use in any post-processing or initialization that occurs below prior to #refresh
ConfigurableEnvironment env = wac.getEnvironment();
if (env instanceof ConfigurableWebEnvironment) {
((ConfigurableWebEnvironment) env).initPropertySources(sc, null);
}
customizeContext(sc, wac);
//刷新
wac.refresh();
}
refresh的定义在 org.springframework.context.ConfigurableApplicationContext#refresh
实现在org.springframework.context.support.AbstractApplicationContext#refresh
@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// 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);
// Invoke factory processors registered as beans in the context.
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
registerBeanPostProcessors(beanFactory);
// 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) {
// 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();
}
}
}
obtainFreshBeanFactory
刷新并获取beanFactory, 这里只是实例化
/**
* Tell the subclass to refresh the internal bean factory.
* @return the fresh BeanFactory instance
* @see #refreshBeanFactory()
* @see #getBeanFactory()
*/
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
refreshBeanFactory();
return getBeanFactory();
}
refreshBeanFactory
org.springframework.context.support.AbstractApplicationContext#refreshBeanFactory
实现org.springframework.context.support.AbstractRefreshableApplicationContext#refreshBeanFactory
/**
* This implementation performs an actual refresh of this context's underlying
* bean factory, shutting down the previous bean factory (if any) and
* initializing a fresh bean factory for the next phase of the context's lifecycle.
*/
@Override
protected final void refreshBeanFactory() throws BeansException {
if (hasBeanFactory()) {
destroyBeans();
closeBeanFactory();
}
try {
DefaultListableBeanFactory beanFactory = createBeanFactory();
beanFactory.setSerializationId(getId());
customizeBeanFactory(beanFactory);
loadBeanDefinitions(beanFactory);
synchronized (this.beanFactoryMonitor) {
this.beanFactory = beanFactory;
}
}
catch (IOException ex) {
throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);
}
}
所谓的refresh就是销毁bean close ,再重新创建和加载 (注意手动注册的bean 再refresh后,不会存在)
getBeanFactory
org.springframework.context.support.AbstractApplicationContext#getBeanFactory
public abstract class AbstractRefreshableApplicationContext extends AbstractApplicationContext {
/** Bean factory for this context. */
@Nullable
private DefaultListableBeanFactory beanFactory;
@Override
public final ConfigurableListableBeanFactory getBeanFactory() {
synchronized (this.beanFactoryMonitor) {
if (this.beanFactory == null) {
throw new IllegalStateException("BeanFactory not initialized or already closed - " +
"call 'refresh' before accessing beans via the ApplicationContext");
}
return this.beanFactory;
}
}
}
可以发现ApplicationContext和BeanFactory是组合的方式, 把BeanFactory相关的操作都委派给beanFactory
prepareBeanFactory
初始化BeanFactory, 配置相关回调(Aware), 内建依赖, 注册相关监听器,环境信息
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// Tell the internal bean factory to use the context's class loader etc.
beanFactory.setBeanClassLoader(getClassLoader());
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
// Configure the bean factory with context callbacks.
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 interface not registered as resolvable type in a plain factory.
// MessageSource registered (and found for autowiring) as a bean.
beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
beanFactory.registerResolvableDependency(ResourceLoader.class, this);
beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
beanFactory.registerResolvableDependency(ApplicationContext.class, this);
// Register early post-processor for detecting inner beans as ApplicationListeners.
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
// Detect a LoadTimeWeaver and prepare for weaving, if found.
if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
// Set a temporary ClassLoader for type matching.
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
// Register default environment beans.
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());
}
}
属性相关 org.springframework.beans.PropertyEditorRegistrySupport#createDefaultEditors
postProcessBeanFactory
当前容器(application)的后置处理, 允许BeanFactory初始化后, bean实例化前的修改
/**
* Modify the application context's internal bean factory after its standard
* initialization. All bean definitions will have been loaded, but no beans
* will have been instantiated yet. This allows for registering special
* BeanPostProcessors etc in certain ApplicationContext implementations.
* @param beanFactory the bean factory used by the application context
*/
protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
}
invokeBeanFactoryPostProcessors
注册并调用BeanFactoryPostProcessor
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 (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
}
具体细节见: org.springframework.context.support.PostProcessorRegistrationDelegate#
invokeBeanFactoryPostProcessors(org.springframework.beans.factory.config.ConfigurableListableBeanFactory, java.util.List<org.springframework.beans.factory.config.BeanFactoryPostProcessor>)
registerBeanPostProcessors
注册BeanPostProcess
public static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
// Register BeanPostProcessorChecker that logs an info message when
// a bean is created during BeanPostProcessor instantiation, i.e. when
// a bean is not eligible for getting processed by all BeanPostProcessors.
int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
// Separate between BeanPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
List<String> orderedPostProcessorNames = new ArrayList<>();
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
priorityOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
orderedPostProcessorNames.add(ppName);
}
else {
nonOrderedPostProcessorNames.add(ppName);
}
}
// First, register the BeanPostProcessors that implement PriorityOrdered.
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
// Next, register the BeanPostProcessors that implement Ordered.
List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
for (String ppName : orderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
orderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
sortPostProcessors(orderedPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, orderedPostProcessors);
// Now, register all regular BeanPostProcessors.
List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
for (String ppName : nonOrderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
nonOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
// Finally, re-register all internal BeanPostProcessors.
sortPostProcessors(internalPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, internalPostProcessors);
// Re-register post-processor for detecting inner beans as ApplicationListeners,
// moving it to the end of the processor chain (for picking up proxies etc).
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}
initMessageSource
国际化(Initialize message source for this context.)
initApplicationEventMulticaster
事件播放器, 配合listener使用(Initialize event multicaster for this context.)
this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
更多详情可以org.springframework.context.event.ApplicationEventMulticaster
实现细节org.springframework.context.event.SimpleApplicationEventMulticaster
#multicastEvent(org.springframework.context.ApplicationEvent, org.springframework.core.ResolvableType)
tips: 默认实现是同步的, 可以设置执行器实现异步
onRefresh
模板方法 bean实例化前的操作(Initialize other special beans in specific context subclasses.) 专门留给子类初始化其它 bean 用，这是一个空的方法
registerListeners
注册监听器(Check for listener beans and register them.)
/**
* Add beans that implement ApplicationListener as listeners.
* Doesn't affect other listeners, which can be added without being beans.
*/
protected void registerListeners() {
// Register statically specified listeners first.
for (ApplicationListener<?> listener : getApplicationListeners()) {
getApplicationEventMulticaster().addApplicationListener(listener);
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let post-processors apply to them!
String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
for (String listenerBeanName : listenerBeanNames) {
getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
}
// Publish early application events now that we finally have a multicaster...
Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
this.earlyApplicationEvents = null;
if (earlyEventsToProcess != null) {
for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
getApplicationEventMulticaster().multicastEvent(earlyEvent);
}
}
}
1.注册静态添加的listener
2.注册bean中的listener
3.发布一些早期事件 (发布事件 event，如果多播器懒加载，还没有初始化则将该事件先放到 earlyApplicationEvents 容器中)
finishBeanFactoryInitialization
实例化所有bean (Instantiate all remaining (non-lazy-init) singletons.)
更多: org.springframework.beans.factory.config.ConfigurableListableBeanFactory#preInstantiateSingletons
finishRefresh
发送相应事件 (publish corresponding event.)
/**
* Finish the refresh of this context, invoking the LifecycleProcessor's
* onRefresh() method and publishing the
* {@link org.springframework.context.event.ContextRefreshedEvent}.
*/
protected void finishRefresh() {
// Clear context-level resource caches (such as ASM metadata from scanning).
clearResourceCaches();
// Initialize lifecycle processor for this context.
initLifecycleProcessor();
// Propagate refresh to lifecycle processor first.
getLifecycleProcessor().onRefresh();
// Publish the final event.
publishEvent(new ContextRefreshedEvent(this));
// Participate in LiveBeansView MBean, if active.
LiveBeansView.registerApplicationContext(this);
}
1.关闭资源缓存
2.初始化生命周期处理器
3.触发生命周期处理器
4.发布容器refresh事件
5.LiveBeansView #getSnapshotAsJson()
live bean的一个snapshot
static void registerApplicationContext(ConfigurableApplicationContext applicationContext) {
String mbeanDomain = applicationContext.getEnvironment().getProperty(MBEAN_DOMAIN_PROPERTY_NAME);
if (mbeanDomain != null) {
synchronized (applicationContexts) {
if (applicationContexts.isEmpty()) {
try {
MBeanServer server = ManagementFactory.getPlatformMBeanServer();
applicationName = applicationContext.getApplicationName();
server.registerMBean(new LiveBeansView(),
new ObjectName(mbeanDomain, MBEAN_APPLICATION_KEY, applicationName));
}
catch (Throwable ex) {
throw new ApplicationContextException("Failed to register LiveBeansView MBean", ex);
}
}
applicationContexts.add(applicationContext);
}
}
}
用console attach后
Web容器
当我们发起一次http请求时, 断点打在 AbstractApplicationContext#refresh 会发现又刷新了一次,
这是因为第一次刷新时spring容器(父容器), 而当第一次请求时,初始化springmvc容器 .并且刷新
at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:651)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:602)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:665)
at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:521)
at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:462)
at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
at javax.servlet.GenericServlet.init(GenericServlet.java:158)
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1230)
- locked <0x1bf7> (a org.apache.catalina.core.StandardWrapper)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1174)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1066)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5370)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5668)
- locked <0xc19> (a org.apache.catalina.core.StandardContext)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
根据堆栈信息找到调用链
org.springframework.web.servlet.FrameworkServlet#initServletBean
org.springframework.web.servlet.FrameworkServlet#initWebApplicationContext
org.springframework.web.servlet.FrameworkServlet#configureAndRefreshWebApplicationContext
SpringBoot中的启动流程
启动方式
我们需要了解SpringBoot的启动方式SpringApplication#run(java.lang.Class<?>, java.lang.String…)即可运行.无需再通过servlet容器的回调
public static ConfigurableApplicationContext run(Class<?>[] primarySources,
String[] args) {
return new SpringApplication(primarySources).run(args);
}
所以这里我们需要关注两部分, 构造函数,以及Run方法
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();
setInitializers((Collection) getSpringFactoriesInstances(
ApplicationContextInitializer.class));
setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
this.mainApplicationClass = deduceMainApplicationClass();
}
从run说起
/**
* 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;
}
启动流程
按照SpringApplicationRunListeners中的定义,可以稍微简单的分下步骤
- listeners.starting();
- listeners.environmentPrepared(environment);
- listeners.contextPrepared(context);
- listeners.contextLoaded(context);
- listeners.started(context);
- listeners.running(context);
运行失败的情况 会调用listeners.failed(context, exception);
server容器的启动方式
根据之前的分析,我们知道之前的传统spring的启动是通过servlet回调, 也就是先启动tomcat.
server容器 -> Spring容器
SpringBoot中是自主启动 , 启动流程是
SpringBoot应用 -> server容器
启动方式
在分析Application的启动流程中 AbstractApplicationContext中留了个#onRefresh的方法,
而在其子类中ServletWebServerApplicationContext重写了onRefresh的方法
@Override
protected void onRefresh() {
super.onRefresh();
try {
createWebServer();
}
catch (Throwable ex) {
throw new ApplicationContextException("Unable to start web server", ex);
}
}
在createWebServer中
private void createWebServer() {
WebServer webServer = this.webServer;
ServletContext servletContext = getServletContext();
if (webServer == null && servletContext == null) {
ServletWebServerFactory factory = getWebServerFactory();
this.webServer = factory.getWebServer(getSelfInitializer());
}
else if (servletContext != null) {
try {
getSelfInitializer().onStartup(servletContext);
}
catch (ServletException ex) {
throw new ApplicationContextException("Cannot initialize servlet context",
ex);
}
}
initPropertySources();
}
Servlet
org.springframework.boot.web.servlet.server.ServletWebServerFactory
Reactive
org.springframework.boot.web.reactive.server.ReactiveWebServerFactory
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