Java tutorial
package com.mystudy.source.spring.mvc; /* * Copyright 2002-2013 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.io.IOException; import java.util.ArrayList; import java.util.Collections; import java.util.Enumeration; import java.util.HashMap; import java.util.HashSet; import java.util.LinkedList; import java.util.List; import java.util.Locale; import java.util.Map; import java.util.Properties; import java.util.Set; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.beans.factory.BeanFactoryUtils; import org.springframework.beans.factory.BeanInitializationException; import org.springframework.beans.factory.NoSuchBeanDefinitionException; import org.springframework.context.ApplicationContext; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.i18n.LocaleContext; import org.springframework.core.OrderComparator; import org.springframework.core.io.ClassPathResource; import org.springframework.core.io.support.PropertiesLoaderUtils; import org.springframework.ui.context.ThemeSource; import org.springframework.util.ClassUtils; import org.springframework.util.StringUtils; import org.springframework.web.context.WebApplicationContext; import org.springframework.web.context.request.ServletWebRequest; import org.springframework.web.context.request.async.WebAsyncManager; import org.springframework.web.context.request.async.WebAsyncUtils; import org.springframework.web.multipart.MultipartException; import org.springframework.web.multipart.MultipartHttpServletRequest; import org.springframework.web.multipart.MultipartResolver; import org.springframework.web.servlet.HandlerInterceptor; import org.springframework.web.servlet.ModelAndView; import org.springframework.web.util.NestedServletException; import org.springframework.web.util.UrlPathHelper; import org.springframework.web.util.WebUtils; /**HTTP???????? * Handlers??web * * Central dispatcher for HTTP request handlers/controllers, e.g. for web UI controllers or HTTP-based remote service * exporters. Dispatches to registered handlers for processing a web request, providing convenient mapping and exception * handling facilities. *DispatchherServle??,??web MVC * <p>This servlet is very flexible: It can be used with just about any workflow, with the installation of the * appropriate adapter classes. It offers the following functionality that distinguishes it from other request-driven * web MVC frameworks: * * 1:javaBean? * <ul> <li>It is based around a JavaBeans configuration mechanism. * *2: ?HandlerMapping ,??? ?? *BeanNameUrlHandlerMappingDefaultAnnotationHandlerMapping. *HandlerMapping?javabeanHandlerMapping?, * <li>It can use any {@link HandlerMapping} implementation - pre-built or provided as part of an application - to * control the routing of requests to handler objects. Default is {@link org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping} * and {@link org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping}. HandlerMapping objects * can be defined as beans in the servlet's application context, implementing the HandlerMapping interface, overriding * the default HandlerMapping if present. HandlerMappings can be given any bean name (they are tested by type). * *3:?HandlerAdapter,??Handler?AdaptersHttpRequestHandlerAdapter,SimpleControllerHandlerAdapter.HttpRequestHandlerAdapterHttpRequestHandler, *SimpleControllerHandlerAdapterController. *?AnnotationMethodHandlerAdapter *HandlerAdapterjavabean * * <li>It can use any {@link HandlerAdapter}; this allows for using any handler interface. Default adapters are {@link * org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter}, {@link org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter}, * for Spring's {@link org.springframework.web.HttpRequestHandler} and {@link org.springframework.web.servlet.mvc.Controller} * interfaces, respectively. A default {@link org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter} * will be registered as well. HandlerAdapter objects can be added as beans in the application context, overriding the * default HandlerAdapters. Like HandlerMappings, HandlerAdapters can be given any bean name (they are tested by type). * *4:dispatcher's exception : * ??HandlerExceptionResolver? * AnnotationMethodHandlerExceptionResolver,ResponseStatusExceptionResolver,DefaultHandlerExceptionResolver * // * <li>The dispatcher's exception resolution strategy can be specified via a {@link HandlerExceptionResolver}, for * example mapping certain exceptions to error pages. Default are * {@link org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerExceptionResolver}, * {@link org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver}, and * {@link org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver}. These HandlerExceptionResolvers can be overridden * through the application context. HandlerExceptionResolver can be given any bean name (they are tested by type). * *5:View *?ViewResolver?,view??View ObjectInternalResourceViewResolver. *ViewRoslolve?bena. * * <li>Its view resolution strategy can be specified via a {@link ViewResolver} implementation, resolving symbolic view * names into View objects. Default is {@link org.springframework.web.servlet.view.InternalResourceViewResolver}. * ViewResolver objects can be added as beans in the application context, overriding the default ViewResolver. * ViewResolvers can be given any bean name (they are tested by type). * * <li>If a {@link View} or view name is not supplied by the user, then the configured {@link * RequestToViewNameTranslator} will translate the current request into a view name. The corresponding bean name is * "viewNameTranslator"; the default is {@link org.springframework.web.servlet.view.DefaultRequestToViewNameTranslator}. * *7:MultipartResolver : * MultipartResolver?? .CommonsMultipartResolver. * MultipartResolver??multipartResolver * * <li>The dispatcher's strategy for resolving multipart requests is determined by a {@link * org.springframework.web.multipart.MultipartResolver} implementation. Implementations for Jakarta Commons FileUpload * and Jason Hunter's COS are included; the typical choise is {@link org.springframework.web.multipart.commons.CommonsMultipartResolver}. * The MultipartResolver bean name is "multipartResolver"; default is none. * *8:?Locale Resolution *LocaleResolver???AcceptHeaderLocaleResolver. * * <li>Its locale resolution strategy is determined by a {@link LocaleResolver}. Out-of-the-box implementations work via * HTTP accept header, cookie, or session. The LocaleResolver bean name is "localeResolver"; default is {@link * org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver}. * *9:??:ThemeResolver *ThemeResolver????ThemeResolverbean??themeResolver,FixedThemeResolver * * <li>Its theme resolution strategy is determined by a {@link ThemeResolver}. Implementations for a fixed theme and for * cookie and session storage are included. The ThemeResolver bean name is "themeResolver"; default is {@link * org.springframework.web.servlet.theme.FixedThemeResolver}. </ul> * *?@RequestMapping?HandlerMappingHandlerAdapter?HandlerMappingHandlerAdapters,???DefaultAnnotationHandlerMappingAnnotationMethodHandlerAdapter *??. * <p><b>NOTE: The {@code @RequestMapping} annotation will only be processed if a corresponding * {@code HandlerMapping} (for type level annotations) and/or {@code HandlerAdapter} (for method level * annotations) is present in the dispatcher.</b> This is the case by default. However, if you are defining custom * {@code HandlerMappings} or {@code HandlerAdapters}, then you need to make sure that a corresponding custom * {@code DefaultAnnotationHandlerMapping} and/or {@code AnnotationMethodHandlerAdapter} is defined as well - * provided that you intend to use {@code @RequestMapping}. * *web???DispatcherServlets.?servlet????,ApplicationContext.?ContextLoaderListenerRoot Application Context? * <p><b>A web application can define any number of DispatcherServlets.</b> Each servlet will operate in its own * namespace, loading its own application context with mappings, handlers, etc. Only the root application context as * loaded by {@link org.springframework.web.context.ContextLoaderListener}, if any, will be shared. * *Spring 3.1,DispatcherServlet?web * <p>As of Spring 3.1, {@code DispatcherServlet} may now be injected with a web * application context, rather than creating its own internally. This is useful in Servlet * 3.0+ environments, which support programmatic registration of servlet instances. See * {@link #DispatcherServlet(WebApplicationContext)} Javadoc for details. * * @author Rod Johnson * @author Juergen Hoeller * @author Rob Harrop * @author Chris Beams * @author Rossen Stoyanchev * @see org.springframework.web.HttpRequestHandler * @see org.springframework.web.servlet.mvc.Controller * @see org.springframework.web.context.ContextLoaderListener */ @SuppressWarnings("serial") public class DispatcherServlet extends FrameworkServlet { /** Well-known name for the MultipartResolver object in the bean factory for this namespace. */ public static final String MULTIPART_RESOLVER_BEAN_NAME = "multipartResolver"; /** Well-known name for the LocaleResolver object in the bean factory for this namespace. */ public static final String LOCALE_RESOLVER_BEAN_NAME = "localeResolver"; /** Well-known name for the ThemeResolver object in the bean factory for this namespace. */ public static final String THEME_RESOLVER_BEAN_NAME = "themeResolver"; /** * Well-known name for the HandlerMapping object in the bean factory for this namespace. * Only used when "detectAllHandlerMappings" is turned off. * @see #setDetectAllHandlerMappings */ public static final String HANDLER_MAPPING_BEAN_NAME = "handlerMapping"; /** * Well-known name for the HandlerAdapter object in the bean factory for this namespace. * Only used when "detectAllHandlerAdapters" is turned off. * @see #setDetectAllHandlerAdapters */ public static final String HANDLER_ADAPTER_BEAN_NAME = "handlerAdapter"; /** * Well-known name for the HandlerExceptionResolver object in the bean factory for this namespace. * Only used when "detectAllHandlerExceptionResolvers" is turned off. * @see #setDetectAllHandlerExceptionResolvers */ public static final String HANDLER_EXCEPTION_RESOLVER_BEAN_NAME = "handlerExceptionResolver"; /** * Well-known name for the RequestToViewNameTranslator object in the bean factory for this namespace. */ public static final String REQUEST_TO_VIEW_NAME_TRANSLATOR_BEAN_NAME = "viewNameTranslator"; /** * Well-known name for the ViewResolver object in the bean factory for this namespace. * Only used when "detectAllViewResolvers" is turned off. * @see #setDetectAllViewResolvers */ public static final String VIEW_RESOLVER_BEAN_NAME = "viewResolver"; /** * Well-known name for the FlashMapManager object in the bean factory for this namespace. */ public static final String FLASH_MAP_MANAGER_BEAN_NAME = "flashMapManager"; /** * Request attribute to hold the current web application context. * Otherwise only the global web app context is obtainable by tags etc. * @see org.springframework.web.servlet.support.RequestContextUtils#getWebApplicationContext */ public static final String WEB_APPLICATION_CONTEXT_ATTRIBUTE = DispatcherServlet.class.getName() + ".CONTEXT"; /** * Request attribute to hold the current LocaleResolver, retrievable by views. * @see org.springframework.web.servlet.support.RequestContextUtils#getLocaleResolver */ public static final String LOCALE_RESOLVER_ATTRIBUTE = DispatcherServlet.class.getName() + ".LOCALE_RESOLVER"; /** * Request attribute to hold the current ThemeResolver, retrievable by views. * @see org.springframework.web.servlet.support.RequestContextUtils#getThemeResolver */ public static final String THEME_RESOLVER_ATTRIBUTE = DispatcherServlet.class.getName() + ".THEME_RESOLVER"; /** * Request attribute to hold the current ThemeSource, retrievable by views. * @see org.springframework.web.servlet.support.RequestContextUtils#getThemeSource */ public static final String THEME_SOURCE_ATTRIBUTE = DispatcherServlet.class.getName() + ".THEME_SOURCE"; /** * Name of request attribute that holds a read-only {@code Map<String,?>} * with "input" flash attributes saved by a previous request, if any. * @see org.springframework.web.servlet.support.RequestContextUtils#getInputFlashMap(HttpServletRequest) */ public static final String INPUT_FLASH_MAP_ATTRIBUTE = DispatcherServlet.class.getName() + ".INPUT_FLASH_MAP"; /** * Name of request attribute that holds the "output" {@link FlashMap} with * attributes to save for a subsequent request. * @see org.springframework.web.servlet.support.RequestContextUtils#getOutputFlashMap(HttpServletRequest) */ public static final String OUTPUT_FLASH_MAP_ATTRIBUTE = DispatcherServlet.class.getName() + ".OUTPUT_FLASH_MAP"; /** * Name of request attribute that holds the {@link FlashMapManager}. * @see org.springframework.web.servlet.support.RequestContextUtils#getFlashMapManager(HttpServletRequest) */ public static final String FLASH_MAP_MANAGER_ATTRIBUTE = DispatcherServlet.class.getName() + ".FLASH_MAP_MANAGER"; /** Log category to use when no mapped handler is found for a request. */ public static final String PAGE_NOT_FOUND_LOG_CATEGORY = "org.springframework.web.servlet.PageNotFound"; /** * Name of the class path resource (relative to the DispatcherServlet class) * that defines DispatcherServlet's default strategy names. */ private static final String DEFAULT_STRATEGIES_PATH = "DispatcherServlet.properties"; /** Additional logger to use when no mapped handler is found for a request. */ protected static final Log pageNotFoundLogger = LogFactory.getLog(PAGE_NOT_FOUND_LOG_CATEGORY); private static final UrlPathHelper urlPathHelper = new UrlPathHelper(); private static final Properties defaultStrategies; static { // Load default strategy implementations from properties file. // This is currently strictly internal and not meant to be customized // by application developers. try { ClassPathResource resource = new ClassPathResource(DEFAULT_STRATEGIES_PATH, DispatcherServlet.class); defaultStrategies = PropertiesLoaderUtils.loadProperties(resource); } catch (IOException ex) { throw new IllegalStateException("Could not load 'DispatcherServlet.properties': " + ex.getMessage()); } } /** Detect all HandlerMappings or just expect "handlerMapping" bean? */ private boolean detectAllHandlerMappings = true; /** Detect all HandlerAdapters or just expect "handlerAdapter" bean? */ private boolean detectAllHandlerAdapters = true; /** Detect all HandlerExceptionResolvers or just expect "handlerExceptionResolver" bean? */ private boolean detectAllHandlerExceptionResolvers = true; /** Detect all ViewResolvers or just expect "viewResolver" bean? */ private boolean detectAllViewResolvers = true; /** Perform cleanup of request attributes after include request? */ private boolean cleanupAfterInclude = true; /** MultipartResolver used by this servlet */ private MultipartResolver multipartResolver; /** LocaleResolver used by this servlet */ private LocaleResolver localeResolver; /** ThemeResolver used by this servlet */ private ThemeResolver themeResolver; /** List of HandlerMappings used by this servlet */ private List<HandlerMapping> handlerMappings; /** List of HandlerAdapters used by this servlet */ private List<HandlerAdapter> handlerAdapters; /** List of HandlerExceptionResolvers used by this servlet */ private List<HandlerExceptionResolver> handlerExceptionResolvers; /** RequestToViewNameTranslator used by this servlet */ private RequestToViewNameTranslator viewNameTranslator; /** FlashMapManager used by this servlet */ private FlashMapManager flashMapManager; /** List of ViewResolvers used by this servlet */ private List<ViewResolver> viewResolvers; /** * Create a new {@code DispatcherServlet} that will create its own internal web * application context based on defaults and values provided through servlet * init-params. Typically used in Servlet 2.5 or earlier environments, where the only * option for servlet registration is through {@code web.xml} which requires the use * of a no-arg constructor. * <p>Calling {@link #setContextConfigLocation} (init-param 'contextConfigLocation') * will dictate which XML files will be loaded by the * {@linkplain #DEFAULT_CONTEXT_CLASS default XmlWebApplicationContext} * <p>Calling {@link #setContextClass} (init-param 'contextClass') overrides the * default {@code XmlWebApplicationContext} and allows for specifying an alternative class, * such as {@code AnnotationConfigWebApplicationContext}. * <p>Calling {@link #setContextInitializerClasses} (init-param 'contextInitializerClasses') * indicates which {@code ApplicationContextInitializer} classes should be used to * further configure the internal application context prior to refresh(). * @see #DispatcherServlet(WebApplicationContext) */ public DispatcherServlet() { super(); } /** * Create a new {@code DispatcherServlet} with the given web application context. This * constructor is useful in Servlet 3.0+ environments where instance-based registration * of servlets is possible through the {@link ServletContext#addServlet} API. * <p>Using this constructor indicates that the following properties / init-params * will be ignored: * <ul> * <li>{@link #setContextClass(Class)} / 'contextClass'</li> * <li>{@link #setContextConfigLocation(String)} / 'contextConfigLocation'</li> * <li>{@link #setContextAttribute(String)} / 'contextAttribute'</li> * <li>{@link #setNamespace(String)} / 'namespace'</li> * </ul> * <p>The given web application context may or may not yet be {@linkplain * ConfigurableApplicationContext#refresh() refreshed}. If it has <strong>not</strong> * already been refreshed (the recommended approach), then the following will occur: * <ul> * <li>If the given context does not already have a {@linkplain * ConfigurableApplicationContext#setParent parent}, the root application context * will be set as the parent.</li> * <li>If the given context has not already been assigned an {@linkplain * ConfigurableApplicationContext#setId id}, one will be assigned to it</li> * <li>{@code ServletContext} and {@code ServletConfig} objects will be delegated to * the application context</li> * <li>{@link #postProcessWebApplicationContext} will be called</li> * <li>Any {@code ApplicationContextInitializer}s specified through the * "contextInitializerClasses" init-param or through the {@link * #setContextInitializers} property will be applied.</li> * <li>{@link ConfigurableApplicationContext#refresh refresh()} will be called if the * context implements {@link ConfigurableApplicationContext}</li> * </ul> * If the context has already been refreshed, none of the above will occur, under the * assumption that the user has performed these actions (or not) per their specific * needs. * <p>See {@link org.springframework.web.WebApplicationInitializer} for usage examples. * @param webApplicationContext the context to use * @see #initWebApplicationContext * @see #configureAndRefreshWebApplicationContext * @see org.springframework.web.WebApplicationInitializer */ public DispatcherServlet(WebApplicationContext webApplicationContext) { super(webApplicationContext); } /** * Set whether to detect all HandlerMapping beans in this servlet's context. Otherwise, * just a single bean with name "handlerMapping" will be expected. * <p>Default is "true". Turn this off if you want this servlet to use a single * HandlerMapping, despite multiple HandlerMapping beans being defined in the context. */ public void setDetectAllHandlerMappings(boolean detectAllHandlerMappings) { this.detectAllHandlerMappings = detectAllHandlerMappings; } /** * Set whether to detect all HandlerAdapter beans in this servlet's context. Otherwise, * just a single bean with name "handlerAdapter" will be expected. * <p>Default is "true". Turn this off if you want this servlet to use a single * HandlerAdapter, despite multiple HandlerAdapter beans being defined in the context. */ public void setDetectAllHandlerAdapters(boolean detectAllHandlerAdapters) { this.detectAllHandlerAdapters = detectAllHandlerAdapters; } /** * Set whether to detect all HandlerExceptionResolver beans in this servlet's context. Otherwise, * just a single bean with name "handlerExceptionResolver" will be expected. * <p>Default is "true". Turn this off if you want this servlet to use a single * HandlerExceptionResolver, despite multiple HandlerExceptionResolver beans being defined in the context. */ public void setDetectAllHandlerExceptionResolvers(boolean detectAllHandlerExceptionResolvers) { this.detectAllHandlerExceptionResolvers = detectAllHandlerExceptionResolvers; } /** * Set whether to detect all ViewResolver beans in this servlet's context. Otherwise, * just a single bean with name "viewResolver" will be expected. * <p>Default is "true". Turn this off if you want this servlet to use a single * ViewResolver, despite multiple ViewResolver beans being defined in the context. */ public void setDetectAllViewResolvers(boolean detectAllViewResolvers) { this.detectAllViewResolvers = detectAllViewResolvers; } /** * Set whether to perform cleanup of request attributes after an include request, that is, * whether to reset the original state of all request attributes after the DispatcherServlet * has processed within an include request. Otherwise, just the DispatcherServlet's own * request attributes will be reset, but not model attributes for JSPs or special attributes * set by views (for example, JSTL's). * <p>Default is "true", which is strongly recommended. Views should not rely on request attributes * having been set by (dynamic) includes. This allows JSP views rendered by an included controller * to use any model attributes, even with the same names as in the main JSP, without causing side * effects. Only turn this off for special needs, for example to deliberately allow main JSPs to * access attributes from JSP views rendered by an included controller. */ public void setCleanupAfterInclude(boolean cleanupAfterInclude) { this.cleanupAfterInclude = cleanupAfterInclude; } /** * This implementation calls {@link #initStrategies}. */ @Override protected void onRefresh(ApplicationContext context) { initStrategies(context); } /** * Initialize the strategy objects that this servlet uses. * <p>May be overridden in subclasses in order to initialize further strategy objects. */ protected void initStrategies(ApplicationContext context) { initMultipartResolver(context); initLocaleResolver(context); initThemeResolver(context); initHandlerMappings(context); initHandlerAdapters(context); initHandlerExceptionResolvers(context); initRequestToViewNameTranslator(context); initViewResolvers(context); initFlashMapManager(context); } /** * Initialize the MultipartResolver used by this class. * <p>If no bean is defined with the given name in the BeanFactory for this namespace, * no multipart handling is provided. */ private void initMultipartResolver(ApplicationContext context) { try { this.multipartResolver = context.getBean(MULTIPART_RESOLVER_BEAN_NAME, MultipartResolver.class); if (logger.isDebugEnabled()) { logger.debug("Using MultipartResolver [" + this.multipartResolver + "]"); } } catch (NoSuchBeanDefinitionException ex) { // Default is no multipart resolver. this.multipartResolver = null; if (logger.isDebugEnabled()) { logger.debug("Unable to locate MultipartResolver with name '" + MULTIPART_RESOLVER_BEAN_NAME + "': no multipart request handling provided"); } } } /** * Initialize the LocaleResolver used by this class. * <p>If no bean is defined with the given name in the BeanFactory for this namespace, * we default to AcceptHeaderLocaleResolver. */ private void initLocaleResolver(ApplicationContext context) { try { this.localeResolver = context.getBean(LOCALE_RESOLVER_BEAN_NAME, LocaleResolver.class); if (logger.isDebugEnabled()) { logger.debug("Using LocaleResolver [" + this.localeResolver + "]"); } } catch (NoSuchBeanDefinitionException ex) { // We need to use the default. this.localeResolver = getDefaultStrategy(context, LocaleResolver.class); if (logger.isDebugEnabled()) { logger.debug("Unable to locate LocaleResolver with name '" + LOCALE_RESOLVER_BEAN_NAME + "': using default [" + this.localeResolver + "]"); } } } /** * Initialize the ThemeResolver used by this class. * <p>If no bean is defined with the given name in the BeanFactory for this namespace, * we default to a FixedThemeResolver. */ private void initThemeResolver(ApplicationContext context) { try { this.themeResolver = context.getBean(THEME_RESOLVER_BEAN_NAME, ThemeResolver.class); if (logger.isDebugEnabled()) { logger.debug("Using ThemeResolver [" + this.themeResolver + "]"); } } catch (NoSuchBeanDefinitionException ex) { // We need to use the default. this.themeResolver = getDefaultStrategy(context, ThemeResolver.class); if (logger.isDebugEnabled()) { logger.debug("Unable to locate ThemeResolver with name '" + THEME_RESOLVER_BEAN_NAME + "': using default [" + this.themeResolver + "]"); } } } /** * Initialize the HandlerMappings used by this class. * <p>If no HandlerMapping beans are defined in the BeanFactory for this namespace, * we default to BeanNameUrlHandlerMapping. */ private void initHandlerMappings(ApplicationContext context) { this.handlerMappings = null; if (this.detectAllHandlerMappings) { // Find all HandlerMappings in the ApplicationContext, including ancestor contexts. Map<String, HandlerMapping> matchingBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerMapping.class, true, false); if (!matchingBeans.isEmpty()) { this.handlerMappings = new ArrayList<HandlerMapping>(matchingBeans.values()); // We keep HandlerMappings in sorted order. OrderComparator.sort(this.handlerMappings); } } else { try { HandlerMapping hm = context.getBean(HANDLER_MAPPING_BEAN_NAME, HandlerMapping.class); this.handlerMappings = Collections.singletonList(hm); } catch (NoSuchBeanDefinitionException ex) { // Ignore, we'll add a default HandlerMapping later. } } // Ensure we have at least one HandlerMapping, by registering // a default HandlerMapping if no other mappings are found. if (this.handlerMappings == null) { this.handlerMappings = getDefaultStrategies(context, HandlerMapping.class); if (logger.isDebugEnabled()) { logger.debug("No HandlerMappings found in servlet '" + getServletName() + "': using default"); } } } /** * Initialize the HandlerAdapters used by this class. * <p>If no HandlerAdapter beans are defined in the BeanFactory for this namespace, * we default to SimpleControllerHandlerAdapter. */ private void initHandlerAdapters(ApplicationContext context) { this.handlerAdapters = null; if (this.detectAllHandlerAdapters) { // Find all HandlerAdapters in the ApplicationContext, including ancestor contexts. Map<String, HandlerAdapter> matchingBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerAdapter.class, true, false); if (!matchingBeans.isEmpty()) { this.handlerAdapters = new ArrayList<HandlerAdapter>(matchingBeans.values()); // We keep HandlerAdapters in sorted order. OrderComparator.sort(this.handlerAdapters); } } else { try { HandlerAdapter ha = context.getBean(HANDLER_ADAPTER_BEAN_NAME, HandlerAdapter.class); this.handlerAdapters = Collections.singletonList(ha); } catch (NoSuchBeanDefinitionException ex) { // Ignore, we'll add a default HandlerAdapter later. } } // Ensure we have at least some HandlerAdapters, by registering // default HandlerAdapters if no other adapters are found. if (this.handlerAdapters == null) { this.handlerAdapters = getDefaultStrategies(context, HandlerAdapter.class); if (logger.isDebugEnabled()) { logger.debug("No HandlerAdapters found in servlet '" + getServletName() + "': using default"); } } } /** * Initialize the HandlerExceptionResolver used by this class. * <p>If no bean is defined with the given name in the BeanFactory for this namespace, * we default to no exception resolver. */ private void initHandlerExceptionResolvers(ApplicationContext context) { this.handlerExceptionResolvers = null; if (this.detectAllHandlerExceptionResolvers) { // Find all HandlerExceptionResolvers in the ApplicationContext, including ancestor contexts. Map<String, HandlerExceptionResolver> matchingBeans = BeanFactoryUtils .beansOfTypeIncludingAncestors(context, HandlerExceptionResolver.class, true, false); if (!matchingBeans.isEmpty()) { this.handlerExceptionResolvers = new ArrayList<HandlerExceptionResolver>(matchingBeans.values()); // We keep HandlerExceptionResolvers in sorted order. OrderComparator.sort(this.handlerExceptionResolvers); } } else { try { HandlerExceptionResolver her = context.getBean(HANDLER_EXCEPTION_RESOLVER_BEAN_NAME, HandlerExceptionResolver.class); this.handlerExceptionResolvers = Collections.singletonList(her); } catch (NoSuchBeanDefinitionException ex) { // Ignore, no HandlerExceptionResolver is fine too. } } // Ensure we have at least some HandlerExceptionResolvers, by registering // default HandlerExceptionResolvers if no other resolvers are found. if (this.handlerExceptionResolvers == null) { this.handlerExceptionResolvers = getDefaultStrategies(context, HandlerExceptionResolver.class); if (logger.isDebugEnabled()) { logger.debug( "No HandlerExceptionResolvers found in servlet '" + getServletName() + "': using default"); } } } /** * Initialize the RequestToViewNameTranslator used by this servlet instance. * <p>If no implementation is configured then we default to DefaultRequestToViewNameTranslator. */ private void initRequestToViewNameTranslator(ApplicationContext context) { try { this.viewNameTranslator = context.getBean(REQUEST_TO_VIEW_NAME_TRANSLATOR_BEAN_NAME, RequestToViewNameTranslator.class); if (logger.isDebugEnabled()) { logger.debug("Using RequestToViewNameTranslator [" + this.viewNameTranslator + "]"); } } catch (NoSuchBeanDefinitionException ex) { // We need to use the default. this.viewNameTranslator = getDefaultStrategy(context, RequestToViewNameTranslator.class); if (logger.isDebugEnabled()) { logger.debug("Unable to locate RequestToViewNameTranslator with name '" + REQUEST_TO_VIEW_NAME_TRANSLATOR_BEAN_NAME + "': using default [" + this.viewNameTranslator + "]"); } } } /** * Initialize the ViewResolvers used by this class. * <p>If no ViewResolver beans are defined in the BeanFactory for this * namespace, we default to InternalResourceViewResolver. */ private void initViewResolvers(ApplicationContext context) { this.viewResolvers = null; if (this.detectAllViewResolvers) { // Find all ViewResolvers in the ApplicationContext, including ancestor contexts. Map<String, ViewResolver> matchingBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(context, ViewResolver.class, true, false); if (!matchingBeans.isEmpty()) { this.viewResolvers = new ArrayList<ViewResolver>(matchingBeans.values()); // We keep ViewResolvers in sorted order. OrderComparator.sort(this.viewResolvers); } } else { try { ViewResolver vr = context.getBean(VIEW_RESOLVER_BEAN_NAME, ViewResolver.class); this.viewResolvers = Collections.singletonList(vr); } catch (NoSuchBeanDefinitionException ex) { // Ignore, we'll add a default ViewResolver later. } } // Ensure we have at least one ViewResolver, by registering // a default ViewResolver if no other resolvers are found. if (this.viewResolvers == null) { this.viewResolvers = getDefaultStrategies(context, ViewResolver.class); if (logger.isDebugEnabled()) { logger.debug("No ViewResolvers found in servlet '" + getServletName() + "': using default"); } } } /** * Initialize the {@link FlashMapManager} used by this servlet instance. * <p>If no implementation is configured then we default to * {@code org.springframework.web.servlet.support.DefaultFlashMapManager}. */ private void initFlashMapManager(ApplicationContext context) { try { this.flashMapManager = context.getBean(FLASH_MAP_MANAGER_BEAN_NAME, FlashMapManager.class); if (logger.isDebugEnabled()) { logger.debug("Using FlashMapManager [" + this.flashMapManager + "]"); } } catch (NoSuchBeanDefinitionException ex) { // We need to use the default. this.flashMapManager = getDefaultStrategy(context, FlashMapManager.class); if (logger.isDebugEnabled()) { logger.debug("Unable to locate FlashMapManager with name '" + FLASH_MAP_MANAGER_BEAN_NAME + "': using default [" + this.flashMapManager + "]"); } } } /** * Return this servlet's ThemeSource, if any; else return {@code null}. * <p>Default is to return the WebApplicationContext as ThemeSource, * provided that it implements the ThemeSource interface. * @return the ThemeSource, if any * @see #getWebApplicationContext() */ public final ThemeSource getThemeSource() { if (getWebApplicationContext() instanceof ThemeSource) { return (ThemeSource) getWebApplicationContext(); } else { return null; } } /** * Obtain this servlet's MultipartResolver, if any. * @return the MultipartResolver used by this servlet, or {@code null} if none * (indicating that no multipart support is available) */ public final MultipartResolver getMultipartResolver() { return this.multipartResolver; } /** * Return the default strategy object for the given strategy interface. * <p>The default implementation delegates to {@link #getDefaultStrategies}, * expecting a single object in the list. * @param context the current WebApplicationContext * @param strategyInterface the strategy interface * @return the corresponding strategy object * @see #getDefaultStrategies */ protected <T> T getDefaultStrategy(ApplicationContext context, Class<T> strategyInterface) { List<T> strategies = getDefaultStrategies(context, strategyInterface); if (strategies.size() != 1) { throw new BeanInitializationException("DispatcherServlet needs exactly 1 strategy for interface [" + strategyInterface.getName() + "]"); } return strategies.get(0); } /** * Create a List of default strategy objects for the given strategy interface. * <p>The default implementation uses the "DispatcherServlet.properties" file (in the same * package as the DispatcherServlet class) to determine the class names. It instantiates * the strategy objects through the context's BeanFactory. * @param context the current WebApplicationContext * @param strategyInterface the strategy interface * @return the List of corresponding strategy objects */ @SuppressWarnings("unchecked") protected <T> List<T> getDefaultStrategies(ApplicationContext context, Class<T> strategyInterface) { String key = strategyInterface.getName(); String value = defaultStrategies.getProperty(key); if (value != null) { String[] classNames = StringUtils.commaDelimitedListToStringArray(value); List<T> strategies = new ArrayList<T>(classNames.length); for (String className : classNames) { try { Class<?> clazz = ClassUtils.forName(className, DispatcherServlet.class.getClassLoader()); Object strategy = createDefaultStrategy(context, clazz); strategies.add((T) strategy); } catch (ClassNotFoundException ex) { throw new BeanInitializationException( "Could not find DispatcherServlet's default strategy class [" + className + "] for interface [" + key + "]", ex); } catch (LinkageError err) { throw new BeanInitializationException( "Error loading DispatcherServlet's default strategy class [" + className + "] for interface [" + key + "]: problem with class file or dependent class", err); } } return strategies; } else { return new LinkedList<T>(); } } /** * Create a default strategy. * <p>The default implementation uses {@link org.springframework.beans.factory.config.AutowireCapableBeanFactory#createBean}. * @param context the current WebApplicationContext * @param clazz the strategy implementation class to instantiate * @return the fully configured strategy instance * @see org.springframework.context.ApplicationContext#getAutowireCapableBeanFactory() * @see org.springframework.beans.factory.config.AutowireCapableBeanFactory#createBean */ protected Object createDefaultStrategy(ApplicationContext context, Class<?> clazz) { return context.getAutowireCapableBeanFactory().createBean(clazz); } /** * Exposes the DispatcherServlet-specific request attributes and delegates to {@link #doDispatch} * for the actual dispatching. */ @Override protected void doService(HttpServletRequest request, HttpServletResponse response) throws Exception { if (logger.isDebugEnabled()) { String requestUri = urlPathHelper.getRequestUri(request); String resumed = WebAsyncUtils.getAsyncManager(request).hasConcurrentResult() ? " resumed" : ""; logger.debug("DispatcherServlet with name '" + getServletName() + "'" + resumed + " processing " + request.getMethod() + " request for [" + requestUri + "]"); } // Keep a snapshot of the request attributes in case of an include, // to be able to restore the original attributes after the include. Map<String, Object> attributesSnapshot = null; if (WebUtils.isIncludeRequest(request)) { logger.debug("Taking snapshot of request attributes before include"); attributesSnapshot = new HashMap<String, Object>(); Enumeration<?> attrNames = request.getAttributeNames(); while (attrNames.hasMoreElements()) { String attrName = (String) attrNames.nextElement(); if (this.cleanupAfterInclude || attrName.startsWith("org.springframework.web.servlet")) { attributesSnapshot.put(attrName, request.getAttribute(attrName)); } } } // Make framework objects available to handlers and view objects. request.setAttribute(WEB_APPLICATION_CONTEXT_ATTRIBUTE, getWebApplicationContext()); request.setAttribute(LOCALE_RESOLVER_ATTRIBUTE, this.localeResolver); request.setAttribute(THEME_RESOLVER_ATTRIBUTE, this.themeResolver); request.setAttribute(THEME_SOURCE_ATTRIBUTE, getThemeSource()); FlashMap inputFlashMap = this.flashMapManager.retrieveAndUpdate(request, response); if (inputFlashMap != null) { request.setAttribute(INPUT_FLASH_MAP_ATTRIBUTE, Collections.unmodifiableMap(inputFlashMap)); } request.setAttribute(OUTPUT_FLASH_MAP_ATTRIBUTE, new FlashMap()); request.setAttribute(FLASH_MAP_MANAGER_ATTRIBUTE, this.flashMapManager); try { doDispatch(request, response); } finally { if (WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) { return; } // Restore the original attribute snapshot, in case of an include. if (attributesSnapshot != null) { restoreAttributesAfterInclude(request, attributesSnapshot); } } } /** 1:?. * 2:HandlerExecutionChain,Handler,handlerHandlerInterceptor? * 3:?HandlerExecutionChain.handlerHandlerAdapter,HadnlerAdapter.supports()????Handler * 4:?lastModified?servlet???,?,? * 5:mappedHandler.applyPreHandle?? * 6:ha.handle(processedRequest, response, mappedHandler.getHandler())?? * 7:asyncManager.isConcurrentHandlingStarted()?? * 9? * 10:?postHandle * WebAsyncManager:?web * ???? * 1: * HandlerExecutionChain:?Handler. * getHandler()?? * ???handlerMappings???, * for (HandlerMapping hm : this.handlerMappings) { if (logger.isTraceEnabled()) { logger.trace( "Testing handler map [" + hm + "] in DispatcherServlet with name '" + getServletName() + "'"); } HandlerExecutionChain handler = hm.getHandler(request); if (handler != null) { return handler; } } return null; } HandlerExecutionChain: : private final Object handler; private HandlerInterceptor[] interceptors; private List<HandlerInterceptor> interceptorList; 1handler?HandlerInterceptor???? 2preHandle??handler 3handler??????HttpServletResponse?SpringMVCpostHandle????afterCompletion?web?? ???????? ?HandlerMapping,handlerMappings.?? HandlerInterceptor? HandlerInterceptor HandlerInterceptorSpringMVC????????????? LocaleChangeInterceptor?? HandlerAdapter boolean supports(Object handler); ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception; long getLastModified(HttpServletRequest request, Object handler); 1:RequestMappingHandlerAdapter?? * Process the actual dispatching to the handler. * <p>The handler will be obtained by applying the servlet's HandlerMappings in order. * The HandlerAdapter will be obtained by querying the servlet's installed HandlerAdapters * to find the first that supports the handler class. * <p>All HTTP methods are handled by this method. It's up to HandlerAdapters or handlers * themselves to decide which methods are acceptable. * @param request current HTTP request * @param response current HTTP response * @throws Exception in case of any kind of processing failure */ protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception { HttpServletRequest processedRequest = request; HandlerExecutionChain mappedHandler = null; boolean multipartRequestParsed = false; WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request); try { ModelAndView mv = null; Exception dispatchException = null; try { //? processedRequest = checkMultipart(request); multipartRequestParsed = processedRequest != request; //??handler // Determine handler for the current request. mappedHandler = getHandler(processedRequest, false); if (mappedHandler == null || mappedHandler.getHandler() == null) { noHandlerFound(processedRequest, response); return; } // ??HandlerAdapter Determine handler adapter for the current request. HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler()); // Process last-modified header, if supported by the handler. String method = request.getMethod(); boolean isGet = "GET".equals(method); if (isGet || "HEAD".equals(method)) { long lastModified = ha.getLastModified(request, mappedHandler.getHandler()); if (logger.isDebugEnabled()) { String requestUri = urlPathHelper.getRequestUri(request); logger.debug("Last-Modified value for [" + requestUri + "] is: " + lastModified); } if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) { return; } } //? if (!mappedHandler.applyPreHandle(processedRequest, response)) { return; } try { //?? Actually invoke the handler. mv = ha.handle(processedRequest, response, mappedHandler.getHandler()); } finally { if (asyncManager.isConcurrentHandlingStarted()) { return; } } applyDefaultViewName(request, mv); mappedHandler.applyPostHandle(processedRequest, response, mv); } catch (Exception ex) { dispatchException = ex; } processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException); } catch (Exception ex) { triggerAfterCompletion(processedRequest, response, mappedHandler, ex); } catch (Error err) { triggerAfterCompletionWithError(processedRequest, response, mappedHandler, err); } finally { if (asyncManager.isConcurrentHandlingStarted()) { // Instead of postHandle and afterCompletion mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response); return; } // Clean up any resources used by a multipart request. if (multipartRequestParsed) { cleanupMultipart(processedRequest); } } } /** * Do we need view name translation? */ private void applyDefaultViewName(HttpServletRequest request, ModelAndView mv) throws Exception { if (mv != null && !mv.hasView()) { mv.setViewName(getDefaultViewName(request)); } } /** * Handle the result of handler selection and handler invocation, which is * either a ModelAndView or an Exception to be resolved to a ModelAndView. */ private void processDispatchResult(HttpServletRequest request, HttpServletResponse response, HandlerExecutionChain mappedHandler, ModelAndView mv, Exception exception) throws Exception { boolean errorView = false; if (exception != null) { if (exception instanceof ModelAndViewDefiningException) { logger.debug("ModelAndViewDefiningException encountered", exception); mv = ((ModelAndViewDefiningException) exception).getModelAndView(); } else { Object handler = (mappedHandler != null ? mappedHandler.getHandler() : null); mv = processHandlerException(request, response, handler, exception); errorView = (mv != null); } } // Did the handler return a view to render? if (mv != null && !mv.wasCleared()) { render(mv, request, response); if (errorView) { WebUtils.clearErrorRequestAttributes(request); } } else { if (logger.isDebugEnabled()) { logger.debug("Null ModelAndView returned to DispatcherServlet with name '" + getServletName() + "': assuming HandlerAdapter completed request handling"); } } if (WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) { // Concurrent handling started during a forward return; } if (mappedHandler != null) { mappedHandler.triggerAfterCompletion(request, response, null); } } /** * Build a LocaleContext for the given request, exposing the request's primary locale as current locale. * <p>The default implementation uses the dispatcher's LocaleResolver to obtain the current locale, * which might change during a request. * @param request current HTTP request * @return the corresponding LocaleContext */ @Override protected LocaleContext buildLocaleContext(final HttpServletRequest request) { return new LocaleContext() { public Locale getLocale() { return localeResolver.resolveLocale(request); } public String toString() { return getLocale().toString(); } }; } /** * Convert the request into a multipart request, and make multipart resolver available. * <p>If no multipart resolver is set, simply use the existing request. * @param request current HTTP request * @return the processed request (multipart wrapper if necessary) * @see MultipartResolver#resolveMultipart */ protected HttpServletRequest checkMultipart(HttpServletRequest request) throws MultipartException { if (this.multipartResolver != null && this.multipartResolver.isMultipart(request)) { if (request instanceof MultipartHttpServletRequest) { logger.debug("Request is already a MultipartHttpServletRequest - if not in a forward, " + "this typically results from an additional MultipartFilter in web.xml"); } else { return this.multipartResolver.resolveMultipart(request); } } // If not returned before: return original request. return request; } /** * Clean up any resources used by the given multipart request (if any). * @param servletRequest current HTTP request * @see MultipartResolver#cleanupMultipart */ protected void cleanupMultipart(HttpServletRequest servletRequest) { MultipartHttpServletRequest req = WebUtils.getNativeRequest(servletRequest, MultipartHttpServletRequest.class); if (req != null) { this.multipartResolver.cleanupMultipart(req); } } /** * Return the HandlerExecutionChain for this request. Try all handler mappings in order. * @param request current HTTP request * @param cache whether to cache the HandlerExecutionChain in a request attribute * @return the HandlerExecutionChain, or {@code null} if no handler could be found * @deprecated as of Spring 3.0.4, in favor of {@link #getHandler(javax.servlet.http.HttpServletRequest)}, * with this method's cache attribute now effectively getting ignored */ @Deprecated protected HandlerExecutionChain getHandler(HttpServletRequest request, boolean cache) throws Exception { return getHandler(request); } /** * Return the HandlerExecutionChain for this request. * <p>Tries all handler mappings in order. * @param request current HTTP request * @return the HandlerExecutionChain, or {@code null} if no handler could be found */ protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception { for (HandlerMapping hm : this.handlerMappings) { if (logger.isTraceEnabled()) { logger.trace("Testing handler map [" + hm + "] in DispatcherServlet with name '" + getServletName() + "'"); } HandlerExecutionChain handler = hm.getHandler(request); if (handler != null) { return handler; } } return null; } /** * No handler found -> set appropriate HTTP response status. * @param request current HTTP request * @param response current HTTP response * @throws Exception if preparing the response failed */ protected void noHandlerFound(HttpServletRequest request, HttpServletResponse response) throws Exception { if (pageNotFoundLogger.isWarnEnabled()) { String requestUri = urlPathHelper.getRequestUri(request); pageNotFoundLogger.warn("No mapping found for HTTP request with URI [" + requestUri + "] in DispatcherServlet with name '" + getServletName() + "'"); } response.sendError(HttpServletResponse.SC_NOT_FOUND); } /** * Return the HandlerAdapter for this handler object. * @param handler the handler object to find an adapter for * @throws ServletException if no HandlerAdapter can be found for the handler. This is a fatal error. */ protected HandlerAdapter getHandlerAdapter(Object handler) throws ServletException { for (HandlerAdapter ha : this.handlerAdapters) { if (logger.isTraceEnabled()) { logger.trace("Testing handler adapter [" + ha + "]"); } if (ha.supports(handler)) { return ha; } } throw new ServletException("No adapter for handler [" + handler + "]: The DispatcherServlet configuration needs to include a HandlerAdapter that supports this handler"); } /** * Determine an error ModelAndView via the registered HandlerExceptionResolvers. * @param request current HTTP request * @param response current HTTP response * @param handler the executed handler, or {@code null} if none chosen at the time of the exception * (for example, if multipart resolution failed) * @param ex the exception that got thrown during handler execution * @return a corresponding ModelAndView to forward to * @throws Exception if no error ModelAndView found */ protected ModelAndView processHandlerException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { // Check registered HandlerExceptionResolvers... ModelAndView exMv = null; for (HandlerExceptionResolver handlerExceptionResolver : this.handlerExceptionResolvers) { exMv = handlerExceptionResolver.resolveException(request, response, handler, ex); if (exMv != null) { break; } } if (exMv != null) { if (exMv.isEmpty()) { return null; } // We might still need view name translation for a plain error model... if (!exMv.hasView()) { exMv.setViewName(getDefaultViewName(request)); } if (logger.isDebugEnabled()) { logger.debug("Handler execution resulted in exception - forwarding to resolved error view: " + exMv, ex); } WebUtils.exposeErrorRequestAttributes(request, ex, getServletName()); return exMv; } throw ex; } /** * Render the given ModelAndView. * <p>This is the last stage in handling a request. It may involve resolving the view by name. * @param mv the ModelAndView to render * @param request current HTTP servlet request * @param response current HTTP servlet response * @throws ServletException if view is missing or cannot be resolved * @throws Exception if there's a problem rendering the view */ protected void render(ModelAndView mv, HttpServletRequest request, HttpServletResponse response) throws Exception { // Determine locale for request and apply it to the response. Locale locale = this.localeResolver.resolveLocale(request); response.setLocale(locale); View view; if (mv.isReference()) { // We need to resolve the view name. view = resolveViewName(mv.getViewName(), mv.getModelInternal(), locale, request); if (view == null) { throw new ServletException("Could not resolve view with name '" + mv.getViewName() + "' in servlet with name '" + getServletName() + "'"); } } else { // No need to lookup: the ModelAndView object contains the actual View object. view = mv.getView(); if (view == null) { throw new ServletException("ModelAndView [" + mv + "] neither contains a view name nor a " + "View object in servlet with name '" + getServletName() + "'"); } } // Delegate to the View object for rendering. if (logger.isDebugEnabled()) { logger.debug("Rendering view [" + view + "] in DispatcherServlet with name '" + getServletName() + "'"); } view.render(mv.getModelInternal(), request, response); } /** * Translate the supplied request into a default view name. * @param request current HTTP servlet request * @return the view name (or {@code null} if no default found) * @throws Exception if view name translation failed */ protected String getDefaultViewName(HttpServletRequest request) throws Exception { return this.viewNameTranslator.getViewName(request); } /** * Resolve the given view name into a View object (to be rendered). * <p>The default implementations asks all ViewResolvers of this dispatcher. * Can be overridden for custom resolution strategies, potentially based on * specific model attributes or request parameters. * @param viewName the name of the view to resolve * @param model the model to be passed to the view * @param locale the current locale * @param request current HTTP servlet request * @return the View object, or {@code null} if none found * @throws Exception if the view cannot be resolved * (typically in case of problems creating an actual View object) * @see ViewResolver#resolveViewName */ protected View resolveViewName(String viewName, Map<String, Object> model, Locale locale, HttpServletRequest request) throws Exception { for (ViewResolver viewResolver : this.viewResolvers) { View view = viewResolver.resolveViewName(viewName, locale); if (view != null) { return view; } } return null; } private void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response, HandlerExecutionChain mappedHandler, Exception ex) throws Exception { if (mappedHandler != null) { mappedHandler.triggerAfterCompletion(request, response, ex); } throw ex; } private void triggerAfterCompletionWithError(HttpServletRequest request, HttpServletResponse response, HandlerExecutionChain mappedHandler, Error error) throws Exception, ServletException { ServletException ex = new NestedServletException("Handler processing failed", error); if (mappedHandler != null) { mappedHandler.triggerAfterCompletion(request, response, ex); } throw ex; } /** * Restore the request attributes after an include. * @param request current HTTP request * @param attributesSnapshot the snapshot of the request attributes before the include */ @SuppressWarnings("unchecked") private void restoreAttributesAfterInclude(HttpServletRequest request, Map<?, ?> attributesSnapshot) { logger.debug("Restoring snapshot of request attributes after include"); // Need to copy into separate Collection here, to avoid side effects // on the Enumeration when removing attributes. Set<String> attrsToCheck = new HashSet<String>(); Enumeration<?> attrNames = request.getAttributeNames(); while (attrNames.hasMoreElements()) { String attrName = (String) attrNames.nextElement(); if (this.cleanupAfterInclude || attrName.startsWith("org.springframework.web.servlet")) { attrsToCheck.add(attrName); } } // Add attributes that may have been removed attrsToCheck.addAll((Set<String>) attributesSnapshot.keySet()); // Iterate over the attributes to check, restoring the original value // or removing the attribute, respectively, if appropriate. for (String attrName : attrsToCheck) { Object attrValue = attributesSnapshot.get(attrName); if (attrValue == null) { if (logger.isDebugEnabled()) { logger.debug("Removing attribute [" + attrName + "] after include"); } request.removeAttribute(attrName); } else if (attrValue != request.getAttribute(attrName)) { if (logger.isDebugEnabled()) { logger.debug("Restoring original value of attribute [" + attrName + "] after include"); } request.setAttribute(attrName, attrValue); } } } }