<?xml version="1.1" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns="http://java.sun.com/xml/ns/javaee"
     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
     version="3.0">
<display-name>xx Web Application</display-name>
<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath*:root-context.xml</param-value>
</context-param>

<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

public class ContextLoaderListener extends ContextLoader implements ServletContextListener

/**
 * Defines a set of methods that a servlet uses to communicate with its servlet
 * container, for example, to get the MIME type of a file, dispatch requests, or
 * write to a log file.
 *
 * There is one context per "web application" per Java Virtual Machine. (A
 * "web application" is a collection of servlets and content installed under a
 * specific subset of the server's URL namespace such as /catalog
 * and possibly installed via a .war file.)
 *
 * In the case of a web application marked "distributed" in its deployment
 * descriptor, there will be one context instance for each virtual machine. In
 * this situation, the context cannot be used as a location to share global
 * information (because the information won't be truly global). Use an external
 * resource like a database instead.
 *
 * The ServletContext object is contained within the
 *{@link ServletConfig}object, which the Web server provides the servlet when
 * the servlet is initialized.
 */

@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.
        // 加载resource，解析Resource，向beanFactory中填充BeanDefinition等bean的元信息。
        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.
            // 实例化非lazy-init的单例。顺带着也会实例化其依赖的bean
            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();
        }
    }
}

"RMI TCP Connection(2)-127.0.0.1@1870" daemon prio=5 tid=0x15 nid=NA runnable
  java.lang.Thread.State: RUNNABLE
      at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:525)
      at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
      at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
      at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
      - locked <0xe5d> (a java.util.concurrent.ConcurrentHashMap)
      at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
      at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
      at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:775)
      at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:861)
      at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:541)

@Override
protected Object createBean(String beanName, RootBeanDefinition mbd, Object[] args) throws BeanCreationException {
    if (logger.isDebugEnabled()) {
        logger.debug("Creating instance of bean '" + beanName + "'");
    }
    RootBeanDefinition mbdToUse = mbd;

    // Make sure bean class is actually resolved at this point, and
    // clone the bean definition in case of a dynamically resolved Class
    // which cannot be stored in the shared merged bean definition.
    Class<?> resolvedClass = resolveBeanClass(mbd, beanName);
    if (resolvedClass != null && !mbd.hasBeanClass() && mbd.getBeanClassName() != null) {
        mbdToUse = new RootBeanDefinition(mbd);
        mbdToUse.setBeanClass(resolvedClass);
    }

    // Prepare method overrides.
    try {
        mbdToUse.prepareMethodOverrides();
    }
    catch (BeanDefinitionValidationException ex) {
        throw new BeanDefinitionStoreException(mbdToUse.getResourceDescription(),
                beanName, "Validation of method overrides failed", ex);
    }

    try {
        // Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.
        // 拦截逻辑
        Object bean = resolveBeforeInstantiation(beanName, mbdToUse);
        if (bean != null) {
            return bean;
        }
    }
    catch (Throwable ex) {
        throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName,
                "BeanPostProcessor before instantiation of bean failed", ex);
    }
    // 实例化
    Object beanInstance = doCreateBean(beanName, mbdToUse, args);
    if (logger.isDebugEnabled()) {
        logger.debug("Finished creating instance of bean '" + beanName + "'");
    }
    return beanInstance;
}

protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args) {
    // Instantiate the bean.
    BeanWrapper instanceWrapper = null;
    if (mbd.isSingleton()) {
        instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
    }
    if (instanceWrapper == null) {
        // 构造bean
        instanceWrapper = createBeanInstance(beanName, mbd, args);
    }
    final Object bean = (instanceWrapper != null ? instanceWrapper.getWrappedInstance() : null);
    Class<?> beanType = (instanceWrapper != null ? instanceWrapper.getWrappedClass() : null);

    // Allow post-processors to modify the merged bean definition.
    synchronized (mbd.postProcessingLock) {
        if (!mbd.postProcessed) {
            // 处理beandefinition的各种后置拦截逻辑，
            // 包括AutowiredAnnotationBeanPostProcessor、CommonAnnotationBeanPostProcessor解析@Resource和@Autowired等标签
            applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
            mbd.postProcessed = true;
        }
    }

    // Eagerly cache singletons to be able to resolve circular references
    // even when triggered by lifecycle interfaces like BeanFactoryAware.
    boolean earlySingletonExposure = (mbd.isSingleton() && this.allowCircularReferences &&
            isSingletonCurrentlyInCreation(beanName));
    if (earlySingletonExposure) {
        if (logger.isDebugEnabled()) {
            logger.debug("Eagerly caching bean '" + beanName +
                    "' to allow for resolving potential circular references");
        }
        addSingletonFactory(beanName, new ObjectFactory<Object>() {
            @Override
            public Object getObject() throws BeansException {
                return getEarlyBeanReference(beanName, mbd, bean);
            }
        });
    }

    // Initialize the bean instance.
    Object exposedObject = bean;
    try {
        // 填充bean，解析@Resource、@Autowired等标签
        populateBean(beanName, mbd, instanceWrapper);
        if (exposedObject != null) {
            // 实例化属性（可能需要代理）
            exposedObject = initializeBean(beanName, exposedObject, mbd);
        }
    }
    catch (Throwable ex) {
        if (ex instanceof BeanCreationException && beanName.equals(((BeanCreationException) ex).getBeanName())) {
            throw (BeanCreationException) ex;
        }
        else {
            throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Initialization of bean failed", ex);
        }
    }

    if (earlySingletonExposure) {
        Object earlySingletonReference = getSingleton(beanName, false);
        if (earlySingletonReference != null) {
            if (exposedObject == bean) {
                exposedObject = earlySingletonReference;
            }
            else if (!this.allowRawInjectionDespiteWrapping && hasDependentBean(beanName)) {
                String[] dependentBeans = getDependentBeans(beanName);
                Set<String> actualDependentBeans = new LinkedHashSet<String>(dependentBeans.length);
                for (String dependentBean : dependentBeans) {
                    if (!removeSingletonIfCreatedForTypeCheckOnly(dependentBean)) {
                        actualDependentBeans.add(dependentBean);
                    }
                }
                if (!actualDependentBeans.isEmpty()) {
                    throw new BeanCurrentlyInCreationException(beanName,
                            "Bean with name '" + beanName + "' has been injected into other beans [" +
                            StringUtils.collectionToCommaDelimitedString(actualDependentBeans) +
                            "] in its raw version as part of a circular reference, but has eventually been " +
                            "wrapped. This means that said other beans do not use the final version of the " +
                            "bean. This is often the result of over-eager type matching - consider using " +
                            "'getBeanNamesOfType' with the 'allowEagerInit' flag turned off, for example.");
                }
            }
        }
    }

    // Register bean as disposable.
    try {
        registerDisposableBeanIfNecessary(beanName, bean, mbd);
    }
    catch (BeanDefinitionValidationException ex) {
        throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
    }

    return exposedObject;
}

   getProxy:164, CglibAopProxy {org.springframework.aop.framework}
   getProxy:109, ProxyFactory {org.springframework.aop.framework}
   createProxy:470, AbstractAutoProxyCreator {org.springframework.aop.framework.autoproxy}
   wrapIfNecessary:350, AbstractAutoProxyCreator {org.springframework.aop.framework.autoproxy}
   postProcessAfterInitialization:299, AbstractAutoProxyCreator {org.springframework.aop.framework.autoproxy}
   applyBeanPostProcessorsAfterInitialization:422, AbstractAutowireCapableBeanFactory {org.springframework.beans.factory.support}
   initializeBean:1583, AbstractAutowireCapableBeanFactory {org.springframework.beans.factory.support}
   doCreateBean:545, AbstractAutowireCapableBeanFactory {org.springframework.beans.factory.support}
   createBean:482, AbstractAutowireCapableBeanFactory {org.springframework.beans.factory.support}
   getObject:306, AbstractBeanFactory$1 {org.springframework.beans.factory.support}
   getSingleton:230, DefaultSingletonBeanRegistry {org.springframework.beans.factory.support}
   doGetBean:302, AbstractBeanFactory {org.springframework.beans.factory.support}
   getBean:197, AbstractBeanFactory {org.springframework.beans.factory.support}
   preInstantiateSingletons:775, DefaultListableBeanFactory {org.springframework.beans.factory.support}
   finishBeanFactoryInitialization:861, AbstractApplicationContext {org.springframework.context.support}
   refresh:541, AbstractApplicationContext {org.springframework.context.support}
   configureAndRefreshWebApplicationContext:444, ContextLoader {org.springframework.web.context}
   initWebApplicationContext:326, ContextLoader {org.springframework.web.context}
   contextInitialized:107, ContextLoaderListener {org.springframework.web.context}