TA貢獻(xiàn)1799條經(jīng)驗(yàn) 獲得超6個(gè)贊
所謂容器，就是上下文，在這同一個(gè)上下文里，大家可以共享一些東西。在Spring應(yīng)用啟動時(shí)，會先讀取web.xml文件，調(diào)用ContextLoaderListener創(chuàng)建Spring容器，也就是你說的父容器。org.springframework.web.context.ContextLoaderListener Listener創(chuàng)建完之后，開始創(chuàng)建Servlet：SpringMVC org.springframework.web.servlet.DispatcherServlet 這時(shí)候這個(gè)DispatcherServlet開始試圖創(chuàng)建SpringMVC的ApplicationContext，它先找剛才由上面那個(gè)ContextLoaderListener創(chuàng)建的Spring的ApplicationContext，找到后，把Spring的ApplicationContext作為參數(shù)傳給DispatcherServlet的ApplicationContext的setParent方法，這樣SpringMVC的容器就變成了Spring容器的兒子。因?yàn)樵赟pringMVC這個(gè)子容器創(chuàng)建的時(shí)候指定了它的Spring父容器，所以兒子能找到父親，所以SpringMVC這個(gè)子容器里的Bean可以調(diào)用父容器的服務(wù)，而父容器不知道有這個(gè)兒子的存在（一個(gè)不負(fù)責(zé)任的父親），父容器里的Bean不能調(diào)用子容器里的服務(wù)。
TA貢獻(xiàn)1942條經(jīng)驗(yàn) 獲得超3個(gè)贊
想必Servlet的關(guān)系就不必多說了，直接上代碼吧HttpServletBean繼承了HttpServlet，init方法如下@Overridepublicfinalvoidinit()throwsServletException{//Letsubclassesdowhateverinitializationtheylike.initServletBean();}看看子類FrameworkServlet#initServletBean方法@OverrideprotectedfinalvoidinitServletBean()throwsServletException{this.webApplicationContext=initWebApplicationContext();initFrameworkServlet();}看看initWebApplicationContextprotectedWebApplicationContextinitWebApplicationContext(){WebApplicationContextrootContext=WebApplicationContextUtils.getWebApplicationContext(getServletContext());WebApplicationContextwac=null;if(this.webApplicationContext!=null){wac=this.webApplicationContext;if(wacinstanceofConfigurableWebApplicationContext){ConfigurableWebApplicationContextcwac=(ConfigurableWebApplicationContext)wac;if(!cwac.isActive()){//Thecontexthasnotyetbeenrefreshed->provideservicessuchas//settingtheparentcontext,settingtheapplicationcontextid,etcif(cwac.getParent()==null){//Thecontextinstancewasinjectedwithoutanexplicitparent->set//therootapplicationcontext(ifany;maybenull)astheparent,看到?jīng)]有，如果有就設(shè)置rootApplicationContext,cwac.setParent(rootContext);}configureAndRefreshWebApplicationContext(cwac);}}}if(wac==null){//Nocontextinstancewasinjectedatconstructiontime->seeifone//hasbeenregisteredintheservletcontext.Ifoneexists,itisassumed//thattheparentcontext(ifany)hasalreadybeensetandthatthe//userhasperformedanyinitializationsuchassettingthecontextidwac=findWebApplicationContext();}if(wac==null){//Nocontextinstanceisdefinedforthisservlet->createalocalonewac=createWebApplicationContext(rootContext);}if(!this.refreshEventReceived){//EitherthecontextisnotaConfigurableApplicationContextwithrefresh//supportorthecontextinjectedatconstructiontimehadalreadybeen//refreshed->triggerinitialonRefreshmanuallyhere.看到這里就不多說了，初始化beanFactoryonRefresh(wac);}if(this.publishContext){StringattrName=getServletContextAttributeName();getServletContext().setAttribute(attrName,wac);}returnwac;}結(jié)束，就是辣么簡單
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