我们看到 initWebApplicationContext() 正是容器初始化的方法，我们继续跟进，我们现在是看容器初始化，其他暂时过掉，后面讲springmvc时在系统讲解
/** * 初始化web容器 WebApplicationContext * 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() { //从ServletContext根容器中获取父容器 WebApplicationContext WebApplicationContext rootContext = WebApplicationContextUtils.getWebApplicationContext(getServletContext()); //声明子容器 WebApplicationContext wac = null; //构建父子容器的关系，这里判断当前容器是否有， // 若存在则作为子容器来给他设置父容器rootcontext 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); } } } //判断子容器是否有引用，在ServletContext根容器中寻找，找到则赋值 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(); } //若上面寻找也没找到，则这里进行容器的赋值 构建一个容器，但是这个容器并没有初始化 只是建立了引用 if (wac == null) { // No context instance is defined for this servlet -> create a local one wac = createWebApplicationContext(rootContext); } //这里触发onRefresh方法进行容器真真初始化 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; }我们看到真真初始化容器的方法 onRefresh() 方法, 跟进找到 DispatcherServlet 中的实现类，其中又调用了 initStrategies() 方法，继续进入
/** * This implementation calls {@link #initStrategies}. */ @Override protected void onRefresh(ApplicationContext context) { initStrategies(context); } /** * 初始化容器，进行springmvc的9大组件初始化 * 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) { //多文件上传组件 initMultipartResolver(context); //国际化组件，也就是本地语言环境 initLocaleResolver(context); //初始化主题模板处理器 initThemeResolver(context); //初始化HandMapping映射 initHandlerMappings(context); //初始化HandlerAdapters参数适配器 initHandlerAdapters(context); //初始化一场拦截组件 initHandlerExceptionResolvers(context); //初始化视图预处理解析器， initRequestToViewNameTranslator(context); //初始化视图解析器 initViewResolvers(context); //初始化FlashMap initFlashMapManager(context); } IOC容器初始化IOC容器的初始化有多种方式，可以是配置文件也可以为 Javaconfig 的方式，常见的如 ClassPathXmlApplicationContext
IOC中主要过程可以概述为_定位_、加载、注册 三个基本过程，我们常见的容器都是 ApplicationContext , ResourceLoader 是所有资源加载的基类，我们可以发现所有的IOC容器都是继承了 BeanFactory ，这也说明了所有的容器本质上都是一个bean工厂
我们可以通过下面的代码获取容器
ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext(CONTEXT_WILDCARD);