所在类：org.springframework.web.servlet.FrameworkServlet

    1. protected WebApplicationContext initWebApplicationContext() {
    2.     WebApplicationContext rootContext = WebApplicationContextUtils.getWebApplicationContext(getServletContext());
    3.     WebApplicationContext wac = null;
    4.     if (this.webApplicationContext != null) { 
    5.         // A context instance was injected at construction time -> use it wac = this.webApplicationContext; 
    6.         if (wac instanceof ConfigurableWebApplicationContext) { 
    7.             ConfigurableWebApplicationContext cwac = (ConfigurableWebApplicationContext) wac; 
    8.             if (!cwac.isActive()) {
    9.                 // The context has not yet been refreshed -> provide services such as 
    10.                 // setting the parent context, setting the application context id, etc
    11.                 if (cwac.getParent() == null) {
    12.                     // The context instance was injected without an explicit parent -> set 
    13.                     // the root application context (if any; may be null) as the parent 
    14.                     cwac.setParent(rootContext); 
    15.                 }
    16.                 configureAndRefreshWebApplicationContext(cwac);
    17.             } 
    18.         } 
    19.     }
    20.     if (wac == null) {
    21.         // No context instance was injected at construction time -> see if one 
    22.         // has been registered in the servlet context. If one exists, it is assumed 
    23.         // that the parent context (if any) has already been set and that the 
    24.         // user has performed any initialization such as setting the context id 
    25.         wac = findWebApplicationContext(); 
    26.     }
    28.     if (wac == null) { 
    29.         // No context instance is defined for this servlet -> create a local one 
    30.         // 创建WebApplicationContext 
    31.         wac = createWebApplicationContext(rootContext);
    32.     }
    34.     if (!this.refreshEventReceived) { 
    35.         // Either the context is not a ConfigurableApplicationContext with refresh 
    36.         // support or the context injected at construction time had already been
    37.         // refreshed -> trigger initial onRefresh manually here. 
    38.         synchronized (this.onRefreshMonitor) { 
    39.             // 刷新WebApplicationContext onRefresh(wac);
    40.         } 
    41.     }
    43.     if (this.publishContext) {
    44.         // Publish the context as a servlet context attribute.
    45.         // 将IOC容器在应用域共享
    46.         String attrName = getServletContextAttributeName(); 
    47.         getServletContext().setAttribute(attrName, wac); 
    48.     }
    49.     return wac; 
    50. }