new 一个对象，该对象不会自动装配，getBean()会，都要写getBean()
但是在web环境中显然没有使用getBean
但是在在web.xml 容器中 配置了监听器

  <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext.xml</param-value>
    </context-param>
    <!--实例化IOC容器，创建Beans-->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

在监听器监听到初始化时（也是交给了Spring处理）

    public WebApplicationContext initWebApplicationContext(ServletContext servletContext) {
        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!");
        } else {
            Log logger = LogFactory.getLog(ContextLoader.class);
            servletContext.log("Initializing Spring root WebApplicationContext");
            if(logger.isInfoEnabled()) {
                logger.info("Root WebApplicationContext: initialization started");
            }

            long startTime = System.currentTimeMillis();

            try {
                if(this.context == null) {
                    this.context = this.createWebApplicationContext(servletContext);
                }

                if(this.context instanceof ConfigurableWebApplicationContext) {
                    ConfigurableWebApplicationContext err = (ConfigurableWebApplicationContext)this.context;
                    if(!err.isActive()) {
                        if(err.getParent() == null) {
                            ApplicationContext elapsedTime = this.loadParentContext(servletContext);
                            err.setParent(elapsedTime);
                        }

                        this.configureAndRefreshWebApplicationContext(err, servletContext);
                    }
                }

                servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, this.context);
                ClassLoader err1 = Thread.currentThread().getContextClassLoader();
                if(err1 == ContextLoader.class.getClassLoader()) {
                    currentContext = this.context;
                } else if(err1 != null) {
                    currentContextPerThread.put(err1, this.context);
                }

                if(logger.isDebugEnabled()) {
                    logger.debug("Published root WebApplicationContext as ServletContext attribute with name [" + WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE + "]");
                }

                if(logger.isInfoEnabled()) {
                    long elapsedTime1 = System.currentTimeMillis() - startTime;
                    logger.info("Root WebApplicationContext: initialization completed in " + elapsedTime1 + " ms");
                }

                return this.context;
            } catch (RuntimeException var8) {
                logger.error("Context initialization failed", var8);
                **servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, var8);**
                throw var8;
            } catch (Error var9) {
                logger.error("Context initialization failed", var9);
                servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, var9);
                throw var9;
            }
        }
    }