Spring初始化源码分析

/**
 * 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 {
   if (logger.isDebugEnabled()) {
      logger.debug("Initializing servlet '" + getServletName() + "'");
   }
   // Set bean properties from init parameters.
   try {
      PropertyValues pvs = new ServletConfigPropertyValues(getServletConfig(), this.requiredProperties);
      BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(this);
      ResourceLoader resourceLoader = new ServletContextResourceLoader(getServletContext());
      bw.registerCustomEditor(Resource.class, new ResourceEditor(resourceLoader, getEnvironment()));
      initBeanWrapper(bw);
      bw.setPropertyValues(pvs, true);
   }
   catch (BeansException ex) {
      logger.error("Failed to set bean properties on servlet '" + getServletName() + "'", ex);
      throw ex;
   }
   // Let subclasses do whatever initialization they like.
   initServletBean();
   if (logger.isDebugEnabled()) {
      logger.debug("Servlet '" + getServletName() + "' configured successfully");
   }
}

/**

- 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 FrameworkServlet '" + getServletName() + "'");
  if (this.logger.isInfoEnabled()) {
     this.logger.info("FrameworkServlet '" + getServletName() + "': initialization started");
  }
  long startTime = System.currentTimeMillis();
  
  try {
     this.webApplicationContext = initWebApplicationContext();
     initFrameworkServlet();
  }
  catch (ServletException ex) {
     this.logger.error("Context initialization failed", ex);
     throw ex;
  }
  catch (RuntimeException ex) {
     this.logger.error("Context initialization failed", ex);
     throw ex;
  }
  
  if (this.logger.isInfoEnabled()) {
     long elapsedTime = System.currentTimeMillis() - startTime;
     this.logger.info("FrameworkServlet '" + getServletName() + "': initialization completed in " +
           elapsedTime + " ms");
  }
  }​

protected WebApplicationContext createWebApplicationContext(ApplicationContext parent) {
  Class<?> contextClass = getContextClass();
  if (this.logger.isDebugEnabled()) {
     this.logger.debug("Servlet with name '" + getServletName() +
           "' will try to create custom WebApplicationContext context of class '" +
           contextClass.getName() + "'" + ", using parent context [" + parent + "]");
  }
  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");
  }
  ConfigurableWebApplicationContext wac =
        (ConfigurableWebApplicationContext) BeanUtils.instantiateClass(contextClass);
  
  wac.setEnvironment(getEnvironment());
  wac.setParent(parent);
  wac.setConfigLocation(getContextConfigLocation());
  
  configureAndRefreshWebApplicationContext(wac);
  
  return wac;
}

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) {
         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;
      }
   }
}