SpringMVC中的DispatcherServlet结构和初始化详解

@Override
public void init(ServletConfig config) throws ServletException {
    this.config = config;
    this.init();
}

public final void init() throws ServletException {
    // 解析init-param参数，并封装成ServletConfigPropertyValues
    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) {
            throw ex;
        }
    }
 
    // Let subclasses do whatever initialization they like.
    initServletBean();
}

@Override
protected final void initServletBean() throws ServletException {
    // 省略日志打印和，try catch部分的代码
    this.webApplicationContext = initWebApplicationContext();
    // 留给子类实现，子类DispatcherServlet没有进行实现
    initFrameworkServlet();
}

protected WebApplicationContext initWebApplicationContext() {
    WebApplicationContext rootContext =
            WebApplicationContextUtils.getWebApplicationContext(getServletContext());
    WebApplicationContext wac = null;
 
    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);
            }
        }
    }
    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();
    }
    if (wac == null) {
        // 确保Spring容器创建并且唯一，所以无论ContextLoaderListener是否启动和refresh
        wac = 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.
        synchronized (this.onRefreshMonitor) {
            onRefresh(wac);
        }
    }
 
    if (this.publishContext) {
        // 将Spring的WebApplicationContext容器，设置到Web容器中
        String attrName = getServletContextAttributeName();
        getServletContext().setAttribute(attrName, wac);
    }
 
    return wac;
}

@Override
protected void onRefresh(ApplicationContext context) {
    initStrategies(context);
}

protected void initStrategies(ApplicationContext context) {
    // 文件上传
    initMultipartResolver(context);
    // i18n相关解析器
    initLocaleResolver(context);
    // 主题解析器（一种主题就是一类网页风格）
    initThemeResolver(context);
    // 请求映射
    initHandlerMappings(context);
    // 适配器，后面请求转发的Controller会专门分析
    initHandlerAdapters(context);
    // 操作异常的解析处理（中途发送异常该调整到哪里）
    initHandlerExceptionResolvers(context);
    // 请求的Controller没有返回View时，该如何解析
    initRequestToViewNameTranslator(context);
    // 视图解析器（ModelAndView中的view字符串怎么进行解析）
    initViewResolvers(context);
    // 请求属性（参数）管理器，主要用于重定向等情况时获取属性，比如post重定向到get
    initFlashMapManager(context);
}

private void initMultipartResolver(ApplicationContext context) {
    // 省略日志打印和try catch的代码
    this.multipartResolver = context.getBean(MULTIPART_RESOLVER_BEAN_NAME, MultipartResolver.class);
}

org.springframework.web.servlet.LocaleResolver=org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver
 
org.springframework.web.servlet.ThemeResolver=org.springframework.web.servlet.theme.FixedThemeResolver
 
org.springframework.web.servlet.HandlerMapping=org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping,\
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping,\
	org.springframework.web.servlet.function.support.RouterFunctionMapping
 
org.springframework.web.servlet.HandlerAdapter=org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter,\
	org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter,\
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter,\
	org.springframework.web.servlet.function.support.HandlerFunctionAdapter
 
 
org.springframework.web.servlet.HandlerExceptionResolver=org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver,\
	org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver,\
	org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver
 
org.springframework.web.servlet.RequestToViewNameTranslator=org.springframework.web.servlet.view.DefaultRequestToViewNameTranslator
 
org.springframework.web.servlet.ViewResolver=org.springframework.web.servlet.view.InternalResourceViewResolver
 
org.springframework.web.servlet.FlashMapManager=org.springframework.web.servlet.support.SessionFlashMapManager