DispatcherServlet的启动和初始化

DispatcherServlet的初始化与Servlet的初始化相关联。DispatcherServlet的初始化是在其基类HttpServletBean中做的。init中的initServletBean是在其子类FrameworkServlet中实现的。initServletBean会创建上下文。

public final void init() throws ServletException {if (logger.isDebugEnabled()) {logger.debug("Initializing servlet '" + getServletName() + "'");}// Set bean properties from init parameters.PropertyValues pvs = new ServletConfigPropertyValues(getServletConfig(), this.requiredProperties);if (!pvs.isEmpty()) {try {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) {if (logger.isErrorEnabled()) {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");}
}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 | 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 initWebApplicationContext() {WebApplicationContext rootContext =WebApplicationContextUtils.getWebApplicationContext(getServletContext());WebApplicationContext wac = null;if (this.webApplicationContext != null) {// A context instance was injected at construction time -> use itwac = 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, etcif (cwac.getParent() == null) {// The context instance was injected without an explicit parent -> set// the root application context (if any; may be null) as the parentcwac.setParent(rootContext);}configureAndRefreshWebApplicationContext(cwac);}}}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 idwac = findWebApplicationContext();}if (wac == null) {// No context instance is defined for this servlet -> create a local onewac = createWebApplicationContext(rootContext);}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.onRefresh(wac);}if (this.publishContext) {// Publish the context as a servlet context attribute.String attrName = getServletContextAttributeName();getServletContext().setAttribute(attrName, wac);if (this.logger.isDebugEnabled()) {this.logger.debug("Published WebApplicationContext of servlet '" + getServletName() +"' as ServletContext attribute with name [" + attrName + "]");}}return wac;
}protected WebApplicationContext createWebApplicationContext(@Nullable 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);String configLocation = getContextConfigLocation();if (configLocation != null) {wac.setConfigLocation(configLocation);}configureAndRefreshWebApplicationContext(wac);return wac;
}

创建完上下文后，在子类DispatcherServlet的onFresh中会调用initStrategies来初始化spring mvc框架。LocaleResolver用来支持国际化，HandlerMapping是请求到控制器之间的映射，ViewResolver用来视图生成。如果没有找到对应的bean,会使用默认的，在DispatcherServlet.properties中有配置默认的策略。

protected void initStrategies(ApplicationContext context) {initMultipartResolver(context);initLocaleResolver(context);initThemeResolver(context);initHandlerMappings(context);initHandlerAdapters(context);initHandlerExceptionResolvers(context);initRequestToViewNameTranslator(context);initViewResolvers(context);initFlashMapManager(context);
}

其类结构为

启动时序图为

DispatcherServlet的启动和初始化相关推荐

【Spring】DispatcherServlet的启动和初始化
使用过SpringMVC的都知道DispatcherServlet,下面介绍下该Servlet的启动与初始化.作为Servlet,DispatcherServlet的启动与Serlvet的启动过程是相 ...
启动未初始化小应用程序_SpringBoot详细打印启动时异常堆栈信息
1. 前言随着我们项目的不断迭代 Bean 的数量会大大增加,如果都在启动时进行初始化会非常耗时.Spring Boot 允许延迟初始化应用程序, 也就是根据需要初始化 Spring Bean,而不 ...
如何在Mysql的Docker容器启动时初始化数据库
1.前言 Docker在开发中使用的越来越多了,最近搞了一个Spring Boot应用,为了方便部署将Mysql也放在Docker中运行.那么怎么初始化 SQL脚本以及数据呢? 我这里有两个传统方案. ...
Quartz详解和使用CommandLineRunner在项目启动时初始化定时任务
文章目录 Quartz介绍自定义CommandLineRunner类: 创建.更新定时任务 service层自定义QuartzJobBean 智能调度组件定时任务实体类: mapper接口: 时 ...
Spring Boot 2 (七)：Spring Boot 如何解决项目启动时初始化资源
Spring Boot 2 (七):Spring Boot 如何解决项目启动时初始化资源在项目启动的时候需要做一些初始化的操作,比如初始化线程池,提前加载好加密证书等.今天就给大家介绍一个 Spri ...
datanode无法启动_Hadoop DataNode启动和初始化过程
简介我们先看DataNode的doc文档的介绍,DataNode是一个类,用于存储一组块,用于DFS部署.单个部署可以有一个或多个DataNode.每个DataNode通信定期与单个NameNode ...
docker 容器启动顺序_Docker容器启动时初始化Mysql数据库
1. 前言 Docker在开发中使用的越来越多了,最近搞了一个Spring Boot应用,为了方便部署将Mysql也放在Docker中运行.那么怎么初始化 SQL脚本以及数据呢? 我这里有两个传统方案 ...
docker mysql数据库初始化_如何在Mysql的Docker容器启动时初始化数据库
1.前言 Docker在开发中使用的越来越多了,最近搞了一个Spring Boot应用,为了方便部署将Mysql也放在Docker中运行.那么怎么初始化 SQL脚本以及数据呢? 我这里有两个传统方案. ...
ServletContentLIstener接口演示ServletContext的启动和初始化
ServletContextListener接口中包含两个方法,一个是contextInitialized()方法, 用来监听ServletContext的启动和初始化:一个是contextDestr ...

DispatcherServlet的启动和初始化

DispatcherServlet的启动和初始化相关推荐

最新文章

热门文章