MVC - DispatcherServlet的初始化过程

概述

DispatcherServlet首先是Sevlet，Servlet有自己的生命周期的方法（init,destory等），那么在看DispatcherServlet初始化时首先需要看源码中DispatcherServlet的类结构设计。

首先我们看DispatcherServlet的类结构关系，在这个类依赖结构中找到init的方法

核心方法

init

init()方法如下, 主要读取web.xml中servlet参数配置，并将交给子类方法initServletBean()继续初始化

/**
  * Map config parameters onto bean properties of this servlet, and
  * invoke subclass initialization.
  * @throws ServletException if bean properties are invalid (or required
  * properties are missing), or if subclass initialization fails.
  */
@Override
public final void init() throws ServletException {

  // 读取web.xml中的servlet配置
  PropertyValues pvs = new ServletConfigPropertyValues(getServletConfig(), this.requiredProperties);
  if (!pvs.isEmpty()) {
    try {
      // 转换成BeanWrapper，为了方便使用Spring的属性注入功能
      BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(this);
      // 注入Resource类型需要依赖于ResourceEditor解析，所以注册Resource类关联到ResourceEditor解析器
      ResourceLoader resourceLoader = new ServletContextResourceLoader(getServletContext());
      bw.registerCustomEditor(Resource.class, new ResourceEditor(resourceLoader, getEnvironment()));
      // 更多的初始化可以让子类去拓展
      initBeanWrapper(bw);
      // 让spring注入namespace,contextConfigLocation等属性
      bw.setPropertyValues(pvs, true);
    }
    catch (BeansException ex) {
      if (logger.isErrorEnabled()) {
        logger.error("Failed to set bean properties on servlet '" + getServletName() + "'", ex);
      }
      throw ex;
    }
  }

  // 让子类去拓展
  initServletBean();
}

读取配置可以从下图看出，正是初始化了我们web.xml中配置

再看下initServletBean()方法，位于FrameworkServlet类中

/**
  * Overridden method of {@link HttpServletBean}, invoked after any bean properties
  * have been set. Creates this servlet's WebApplicationContext.
  */
@Override
protected final void initServletBean() throws ServletException {
  getServletContext().log("Initializing Spring " + getClass().getSimpleName() + " '" + getServletName() + "'");
  if (logger.isInfoEnabled()) {
    logger.info("Initializing Servlet '" + getServletName() + "'");
  }
  long startTime = System.currentTimeMillis();

  try {
    // 最重要的是这个方法
    this.webApplicationContext = initWebApplicationContext();

    // 可以让子类进一步拓展
    initFrameworkServlet();
  }
  catch (ServletException | RuntimeException ex) {
    logger.error("Context initialization failed", ex);
    throw ex;
  }

  if (logger.isDebugEnabled()) {
    String value = this.enableLoggingRequestDetails ?
        "shown which may lead to unsafe logging of potentially sensitive data" :
        "masked to prevent unsafe logging of potentially sensitive data";
    logger.debug("enableLoggingRequestDetails='" + this.enableLoggingRequestDetails +
        "': request parameters and headers will be " + value);
  }

  if (logger.isInfoEnabled()) {
    logger.info("Completed initialization in " + (System.currentTimeMillis() - startTime) + " ms");
  }
}

initWebApplicationContext

initWebApplicationContext用来初始化和刷新WebApplicationContext。

这个方法主要做了以下几步：

从ServletContext中获取第一步中创建的SpringMVC根上下文，为下面做准备
根据init-param中的contextAttribute属性值从ServletContext查找是否存在上下文对象
以XmlWebApplicationContext作为Class类型创建上下文对象，设置父类上下文，并完成刷新
执行子类扩展方法onRefresh，在DispatcherServlet内初始化所有web相关组件
将servlet子上下文对象发布到ServletContext

org.springframework.web.servlet.FrameworkServlet#initWebApplicationContext() 方法如下

/**
  * Initialize and publish the WebApplicationContext for this servlet.
  * <p>Delegates to {@link #createWebApplicationContext} for actual creation
  * of the context. Can be overridden in subclasses.
  * @return the WebApplicationContext instance
  * @see #FrameworkServlet(WebApplicationContext)
  * @see #setContextClass
  * @see #setContextConfigLocation
  */
protected WebApplicationContext initWebApplicationContext() {
  WebApplicationContext rootContext =
      WebApplicationContextUtils.getWebApplicationContext(getServletContext());
  WebApplicationContext wac = null;

  // 如果在构造函数已经被初始化
  if (this.webApplicationContext != null) {
    // A context instance was injected at construction time -> use it
    wac = this.webApplicationContext;
    if (wac instanceof ConfigurableWebApplicationContext) {
      ConfigurableWebApplicationContext cwac = (ConfigurableWebApplicationContext) wac;
      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 -> set
          // the root application context (if any; may be null) as the parent
          cwac.setParent(rootContext);
        }
        configureAndRefreshWebApplicationContext(cwac);
      }
    }
  }
  // 没有在构造函数中初始化，则尝试通过contextAttribute初始化
  if (wac == null) {
    // No context instance was injected at construction time -> see if one
    // has been registered in the servlet context. If one exists, it is assumed
    // that the parent context (if any) has already been set and that the
    // user has performed any initialization such as setting the context id
    wac = findWebApplicationContext();
  }

  // 还没有的话，只能重新创建了
  if (wac == null) {
    // No context instance is defined for this servlet -> create a local one
    wac = createWebApplicationContext(rootContext);
  }

  if (!this.refreshEventReceived) {
    // Either the context is not a ConfigurableApplicationContext with refresh
    // support or the context injected at construction time had already been
    // refreshed -> trigger initial onRefresh manually here.
    synchronized (this.onRefreshMonitor) {
      onRefresh(wac);
    }
  }

  if (this.publishContext) {
    // Publish the context as a servlet context attribute.
    String attrName = getServletContextAttributeName();
    getServletContext().setAttribute(attrName, wac);
  }

  return wac;
}

webApplicationContext只会初始化一次，依次尝试构造函数初始化，没有则通过contextAttribute初始化，仍没有则创建新的

createWebApplicationContext方法创建SpringMVC的应用上下文，并调用configureAndRefreshWebApplicationContext方法进行上下文的刷新。创建的createWebApplicationContext方法如下

/**
  * Instantiate the WebApplicationContext for this servlet, either a default
  * {@link org.springframework.web.context.support.XmlWebApplicationContext}
  * or a {@link #setContextClass custom context class}, if set.
  * <p>This implementation expects custom contexts to implement the
  * {@link org.springframework.web.context.ConfigurableWebApplicationContext}
  * interface. Can be overridden in subclasses.
  * <p>Do not forget to register this servlet instance as application listener on the
  * created context (for triggering its {@link #onRefresh callback}, and to call
  * {@link org.springframework.context.ConfigurableApplicationContext#refresh()}
  * before returning the context instance.
  * @param parent the parent ApplicationContext to use, or {@code null} if none
  * @return the WebApplicationContext for this servlet
  * @see org.springframework.web.context.support.XmlWebApplicationContext
  */
protected WebApplicationContext createWebApplicationContext(@Nullable ApplicationContext parent) {
  Class<?> contextClass = getContextClass();
  if (!ConfigurableWebApplicationContext.class.isAssignableFrom(contextClass)) {
    throw new ApplicationContextException(
        "Fatal initialization error in servlet with name '" + getServletName() +
        "': custom WebApplicationContext class [" + contextClass.getName() +
        "] is not of type ConfigurableWebApplicationContext");
  }

  // 通过反射方式初始化
  ConfigurableWebApplicationContext wac =
      (ConfigurableWebApplicationContext) BeanUtils.instantiateClass(contextClass);

  wac.setEnvironment(getEnvironment());
  wac.setParent(parent);
  String configLocation = getContextConfigLocation(); // 就是前面Demo中的springmvc.xml
  if (configLocation != null) {
    wac.setConfigLocation(configLocation);
  }

  // 初始化Spring环境
  configureAndRefreshWebApplicationContext(wac);

  return wac;
}

configureAndRefreshWebApplicationContext会先将新创建的这个上下文与servletcontext绑定，然后进行刷新操作，这个刷新操作就IOC的执行过程一样，configureAndRefreshWebApplicationContext方法初始化设置Spring环境

protected void configureAndRefreshWebApplicationContext(ConfigurableWebApplicationContext wac) {
  // 设置context ID
  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
    if (this.contextId != null) {
      wac.setId(this.contextId);
    }
    else {
      // Generate default id...
      wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX +
          ObjectUtils.getDisplayString(getServletContext().getContextPath()) + '/' + getServletName());
    }
  }

  // 设置servletContext, servletConfig, namespace, listener...
  wac.setServletContext(getServletContext());
  wac.setServletConfig(getServletConfig());
  wac.setNamespace(getNamespace());
  wac.addApplicationListener(new SourceFilteringListener(wac, new ContextRefreshListener()));

  // 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(getServletContext(), getServletConfig());
  }

  // 让子类去拓展
  postProcessWebApplicationContext(wac);
  applyInitializers(wac);

  // Spring环境初始化完了，就可以初始化DispatcherServlet处理流程中需要的组件了。
  wac.refresh();
}

到这一步为止，就创建了3个context，分别为：

ServletContext：全局唯一，tomcat启动该web项目了创建
Spring的context：由servletcontext的监听器contextloaderlistener创建，默认读取servletcontext.xml配置，具体内容参考我们之前介绍的IOC的源码实现。同时该cntext与servletcontext互相关联，该context被注册到servletcontext中以webapplicationcontext属性存在。
SpringMVC的context：SpringMVC初始化DispacherServlet时创建的上下文，该context为Spring的context的子容器，可以访问Spring容器中的内容（子容器可以访问父容器中的内容，但是反过来不行）。

经过上面两个步骤，DispatcherServlet父类中的流程已经全部走完，这几个步骤主要的功能就是生成了SpringMVC容器，并将其与ServletContext、Spring容器相关联。

refresh

有了webApplicationContext后，就开始刷新了（onRefresh()方法），这个方法是FrameworkServlet提供的模板方法，由子类DispatcherServlet来实现的。

/**
  * This implementation calls {@link #initStrategies}.
  */
@Override
protected void onRefresh(ApplicationContext context) {
  initStrategies(context);
}

刷新主要是调用initStrategies(context)方法对DispatcherServlet中的组件进行初始化，这些组件就是在SpringMVC请求流程中包的主要组件。

/**
  * Initialize the strategy objects that this servlet uses.
  * <p>May be overridden in subclasses in order to initialize further strategy objects.
  */
protected void initStrategies(ApplicationContext context) {
  initMultipartResolver(context);
  initLocaleResolver(context);
  initThemeResolver(context);

  // 主要看如下三个方法
  initHandlerMappings(context);
  initHandlerAdapters(context);
  initHandlerExceptionResolvers(context);

  initRequestToViewNameTranslator(context);
  initViewResolvers(context);
  initFlashMapManager(context);
}

initHanlderxxx

主要看initHandlerXXX相关的方法，它们之间的关系可以看SpringMVC的请求流程：

HandlerMapping是映射处理器
HandlerAdpter是处理适配器，它用来找到你的Controller中的处理方法
HandlerExceptionResolver是当遇到处理异常时的异常解析器

initHandlerMapping

该方法负责进行HandlerMapping接口实现类的加载。HandlerMapping接口主要用来提供request 请求对象和Handler对象映射关系的接口。所谓request对象比如web应用中的http 请求，Handler对象则指的是对应rquest请求的相关处理逻辑。

首先判断是否查找所有HandlerMapping(默认为true)。如果为是，则从上下文(包括所有父上下文)中查询类型为HandlerMapping的Bean,并进行排序。如果为否，则从上下文中按指定名称去寻找。如果都没有找到，提供一个默认的实现。这个默认实现从DispatcherServlet同级目录的DispatcherServlet.properties中加载得。

/**
  * Initialize the HandlerAdapters used by this class.
  * <p>If no HandlerAdapter beans are defined in the BeanFactory for this namespace,
  * we default to SimpleControllerHandlerAdapter.
  */
private void initHandlerAdapters(ApplicationContext context) {
  this.handlerAdapters = null;

  if (this.detectAllHandlerAdapters) {
    // Find all HandlerAdapters in the ApplicationContext, including ancestor contexts.
    Map<String, HandlerAdapter> matchingBeans =
        BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerAdapter.class, true, false);
    if (!matchingBeans.isEmpty()) {
      this.handlerAdapters = new ArrayList<>(matchingBeans.values());
      // We keep HandlerAdapters in sorted order.
      AnnotationAwareOrderComparator.sort(this.handlerAdapters);
    }
  }
  else {
    try {
      HandlerAdapter ha = context.getBean(HANDLER_ADAPTER_BEAN_NAME, HandlerAdapter.class);
      this.handlerAdapters = Collections.singletonList(ha);
    }
    catch (NoSuchBeanDefinitionException ex) {
      // Ignore, we'll add a default HandlerAdapter later.
    }
  }

  // Ensure we have at least some HandlerAdapters, by registering
  // default HandlerAdapters if no other adapters are found.
  if (this.handlerAdapters == null) {
    this.handlerAdapters = getDefaultStrategies(context, HandlerAdapter.class);
    if (logger.isTraceEnabled()) {
      logger.trace("No HandlerAdapters declared for servlet '" + getServletName() +
          "': using default strategies from DispatcherServlet.properties");
    }
  }
}

/**
  * Initialize the HandlerExceptionResolver used by this class.
  * <p>If no bean is defined with the given name in the BeanFactory for this namespace,
  * we default to no exception resolver.
  */
private void initHandlerExceptionResolvers(ApplicationContext context) {
  this.handlerExceptionResolvers = null;

  if (this.detectAllHandlerExceptionResolvers) {
    // Find all HandlerExceptionResolvers in the ApplicationContext, including ancestor contexts.
    Map<String, HandlerExceptionResolver> matchingBeans = BeanFactoryUtils
        .beansOfTypeIncludingAncestors(context, HandlerExceptionResolver.class, true, false);
    if (!matchingBeans.isEmpty()) {
      this.handlerExceptionResolvers = new ArrayList<>(matchingBeans.values());
      // We keep HandlerExceptionResolvers in sorted order.
      AnnotationAwareOrderComparator.sort(this.handlerExceptionResolvers);
    }
  }
  else {
    try {
      HandlerExceptionResolver her =
          context.getBean(HANDLER_EXCEPTION_RESOLVER_BEAN_NAME, HandlerExceptionResolver.class);
      this.handlerExceptionResolvers = Collections.singletonList(her);
    }
    catch (NoSuchBeanDefinitionException ex) {
      // Ignore, no HandlerExceptionResolver is fine too.
    }
  }

  // Ensure we have at least some HandlerExceptionResolvers, by registering
  // default HandlerExceptionResolvers if no other resolvers are found.
  if (this.handlerExceptionResolvers == null) {
    this.handlerExceptionResolvers = getDefaultStrategies(context, HandlerExceptionResolver.class);
    if (logger.isTraceEnabled()) {
      logger.trace("No HandlerExceptionResolvers declared in servlet '" + getServletName() +
          "': using default strategies from DispatcherServlet.properties");
    }
  }
}

initHandlerAdapters

通过initHandlerMappings已经将request通过HandlerMapping(处理器映射器)将请求映射到了对应的Handler上，这一步就需要考虑如何解析并执行该handler对象。

这里Spring使用了适配器模式，主要是因为handler对象有两种不同的类型。

/**
  * Initialize the HandlerAdapters used by this class.
  * <p>If no HandlerAdapter beans are defined in the BeanFactory for this namespace,
  * we default to SimpleControllerHandlerAdapter.
  */
private void initHandlerAdapters(ApplicationContext context) {
  this.handlerAdapters = null;

  if (this.detectAllHandlerAdapters) {
    // Find all HandlerAdapters in the ApplicationContext, including ancestor contexts.
    Map<String, HandlerAdapter> matchingBeans =
        BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerAdapter.class, true, false);
    if (!matchingBeans.isEmpty()) {
      this.handlerAdapters = new ArrayList<>(matchingBeans.values());
      // We keep HandlerAdapters in sorted order.
      AnnotationAwareOrderComparator.sort(this.handlerAdapters);
    }
  }
  else {
    try {
      HandlerAdapter ha = context.getBean(HANDLER_ADAPTER_BEAN_NAME, HandlerAdapter.class);
      this.handlerAdapters = Collections.singletonList(ha);
    }
    catch (NoSuchBeanDefinitionException ex) {
      // Ignore, we'll add a default HandlerAdapter later.
    }
  }

  // Ensure we have at least some HandlerAdapters, by registering
  // default HandlerAdapters if no other adapters are found.
  if (this.handlerAdapters == null) {
    this.handlerAdapters = getDefaultStrategies(context, HandlerAdapter.class);
    if (logger.isTraceEnabled()) {
      logger.trace("No HandlerAdapters declared for servlet '" + getServletName() +
          "': using default strategies from DispatcherServlet.properties");
    }
  }
}

/**
  * Initialize the HandlerExceptionResolver used by this class.
  * <p>If no bean is defined with the given name in the BeanFactory for this namespace,
  * we default to no exception resolver.
  */
private void initHandlerExceptionResolvers(ApplicationContext context) {
  this.handlerExceptionResolvers = null;

  if (this.detectAllHandlerExceptionResolvers) {
    // Find all HandlerExceptionResolvers in the ApplicationContext, including ancestor contexts.
    Map<String, HandlerExceptionResolver> matchingBeans = BeanFactoryUtils
        .beansOfTypeIncludingAncestors(context, HandlerExceptionResolver.class, true, false);
    if (!matchingBeans.isEmpty()) {
      this.handlerExceptionResolvers = new ArrayList<>(matchingBeans.values());
      // We keep HandlerExceptionResolvers in sorted order.
      AnnotationAwareOrderComparator.sort(this.handlerExceptionResolvers);
    }
  }
  else {
    try {
      HandlerExceptionResolver her =
          context.getBean(HANDLER_EXCEPTION_RESOLVER_BEAN_NAME, HandlerExceptionResolver.class);
      this.handlerExceptionResolvers = Collections.singletonList(her);
    }
    catch (NoSuchBeanDefinitionException ex) {
      // Ignore, no HandlerExceptionResolver is fine too.
    }
  }

  // Ensure we have at least some HandlerExceptionResolvers, by registering
  // default HandlerExceptionResolvers if no other resolvers are found.
  if (this.handlerExceptionResolvers == null) {
    this.handlerExceptionResolvers = getDefaultStrategies(context, HandlerExceptionResolver.class);
    if (logger.isTraceEnabled()) {
      logger.trace("No HandlerExceptionResolvers declared in servlet '" + getServletName() +
          "': using default strategies from DispatcherServlet.properties");
    }
  }
}

最后看下初始化的日志：

21:30:33.163 [RMI TCP Connection(2)-127.0.0.1] INFO org.springframework.web.servlet.DispatcherServlet - Initializing Servlet 'springmvc-demo'
21:30:38.242 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.web.context.support.XmlWebApplicationContext - Refreshing WebApplicationContext for namespace 'springmvc-demo-servlet'
21:30:39.256 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.context.annotation.ClassPathBeanDefinitionScanner - Identified candidate component class: file [/Users/pdai/pdai/www/tech-pdai-spring-demos/011-spring-framework-demo-springmvc/target/011-spring-framework-demo-springmvc-1.0-SNAPSHOT/WEB-INF/classes/tech/pdai/springframework/springmvc/controller/UserController.class]
21:30:39.261 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.context.annotation.ClassPathBeanDefinitionScanner - Identified candidate component class: file [/Users/pdai/pdai/www/tech-pdai-spring-demos/011-spring-framework-demo-springmvc/target/011-spring-framework-demo-springmvc-1.0-SNAPSHOT/WEB-INF/classes/tech/pdai/springframework/springmvc/dao/UserDaoImpl.class]
21:30:39.274 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.context.annotation.ClassPathBeanDefinitionScanner - Identified candidate component class: file [/Users/pdai/pdai/www/tech-pdai-spring-demos/011-spring-framework-demo-springmvc/target/011-spring-framework-demo-springmvc-1.0-SNAPSHOT/WEB-INF/classes/tech/pdai/springframework/springmvc/service/UserServiceImpl.class]
21:30:39.546 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.xml.XmlBeanDefinitionReader - Loaded 29 bean definitions from class path resource [springmvc.xml]
21:30:39.711 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalConfigurationAnnotationProcessor'
21:30:39.973 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerProcessor'
21:30:39.984 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerFactory'
21:30:39.995 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalAutowiredAnnotationProcessor'
21:30:40.003 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalCommonAnnotationProcessor'
21:30:40.042 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.ui.context.support.UiApplicationContextUtils - Unable to locate ThemeSource with name 'themeSource': using default [org.springframework.ui.context.support.ResourceBundleThemeSource@791af912]
21:30:40.052 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'userController'
21:30:40.136 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'userServiceImpl'
21:30:40.140 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'userDaoImpl'
21:30:40.147 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.web.servlet.resource.DefaultServletHttpRequestHandler#0'
21:30:40.153 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.web.servlet.handler.SimpleUrlHandlerMapping#0'
21:30:40.350 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.web.servlet.handler.MappedInterceptor#0'
21:30:40.356 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.format.support.FormattingConversionServiceFactoryBean#0'
21:30:40.741 [RMI TCP Connection(2)-127.0.0.1] DEBUG _org.springframework.web.servlet.HandlerMapping.Mappings - 'org.springframework.web.servlet.handler.SimpleUrlHandlerMapping#0' {/**=org.springframework.web.servlet.resource.DefaultServletHttpRequestHandler@216c0f1f}
21:30:40.742 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'mvcCorsConfigurations'
21:30:40.742 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping'
21:30:40.792 [RMI TCP Connection(2)-127.0.0.1] DEBUG _org.springframework.web.servlet.HandlerMapping.Mappings - 'org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping' {}
21:30:40.792 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter'
21:30:40.793 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter'
21:30:40.794 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'localeResolver'
21:30:40.796 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'themeResolver'
21:30:40.798 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'viewNameTranslator'
21:30:40.799 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'flashMapManager'
21:30:40.805 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'mvcContentNegotiationManager'
21:30:40.887 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping'
21:30:41.150 [RMI TCP Connection(2)-127.0.0.1] DEBUG _org.springframework.web.servlet.HandlerMapping.Mappings - 
    t.p.s.s.c.UserController:
    { [/user]}: list(HttpServletRequest,HttpServletResponse)
21:30:41.202 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping - 1 mappings in 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping'
21:30:41.202 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter'
21:30:41.626 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter - ControllerAdvice beans: none
21:30:41.738 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'mvcUriComponentsContributor'
21:30:41.786 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter - ControllerAdvice beans: none
21:30:41.806 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver#0'
21:30:41.919 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver - ControllerAdvice beans: none
21:30:41.920 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver#0'
21:30:41.949 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver#0'
21:30:41.967 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'jspViewResolver'
21:30:44.214 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.web.servlet.DispatcherServlet - Detected AcceptHeaderLocaleResolver
21:30:44.214 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.web.servlet.DispatcherServlet - Detected FixedThemeResolver
21:31:02.141 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.web.servlet.DispatcherServlet - Detected org.springframework.web.servlet.view.DefaultRequestToViewNameTranslator@d57bc91
21:31:03.483 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.web.servlet.DispatcherServlet - Detected org.springframework.web.servlet.support.SessionFlashMapManager@2b4e795e
21:44:08.180 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.jndi.JndiTemplate - Looking up JNDI object with name [java:comp/env/spring.liveBeansView.mbeanDomain]
21:44:08.185 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.jndi.JndiLocatorDelegate - Converted JNDI name [java:comp/env/spring.liveBeansView.mbeanDomain] not found - trying original name [spring.liveBeansView.mbeanDomain]. javax.naming.NameNotFoundException: 名称[spring.liveBeansView.mbeanDomain]未在此上下文中绑定。找不到[spring.liveBeansView.mbeanDomain]。
21:44:08.185 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.jndi.JndiTemplate - Looking up JNDI object with name [spring.liveBeansView.mbeanDomain]
21:44:08.185 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.jndi.JndiPropertySource - JNDI lookup for name [spring.liveBeansView.mbeanDomain] threw NamingException with message: 名称[spring.liveBeansView.mbeanDomain]未在此上下文中绑定。找不到[spring.liveBeansView.mbeanDomain]。. Returning null.
21:44:08.195 [RMI TCP Connection(2)-127.0.0.1] DEBUG org.springframework.web.servlet.DispatcherServlet - enableLoggingRequestDetails='false': request parameters and headers will be masked to prevent unsafe logging of potentially sensitive data
21:44:08.195 [RMI TCP Connection(2)-127.0.0.1] INFO org.springframework.web.servlet.DispatcherServlet

总结

整体流程如下图：

初始化整体流程如下：

加载配置文件：Spring MVC的配置文件一般为 XML 格式，通过 ApplicationContext 来加载配置文件，获取相关的bean。
初始化 DispatcherServlet：DispatcherServlet 是整个 Spring MVC 的核心，它继承了 HttpServlet，实现了对 HTTP 请求的处理和响应。在初始化 DispatcherServlet 时，会调用其 init() 方法，并且为其设置一些参数，例如 SpringMVC 配置文件的位置等。
初始化 HandlerMapping：HandlerMapping负责将请求映射到相应的Controller上，DispatcherServlet在初始化时会初始化HandlerMapping，并将其注册到自己的属性中。
初始化 HandlerAdapter：HandlerAdapter 用于将请求对象转换成 ModelAndView 对象。在初始化时，DispatcherServlet 会根据 HandlerMapping 获取相应的 Controller，并生成相应的 HandlerAdapter。
初始化 ViewResolver：ViewResolver 用于将 ModelAndView 对象渲染成具体的视图（如JSP、HTML等）。在初始化时，DispatcherServlet 会根据 ViewResolver 的配置，生成相应的ViewResolver 对象。
启动 Spring MVC：DispatcherServlet 在初始化完成后，就可以监听HTTP请求，并将请求分发到相应的 Controller上进行处理。处理完成后，将 ModelAndView 对象交给 ViewResolver 进行渲染。