Package org.springframework.web.servlet

Class DispatcherServlet

java.lang.Object
jakarta.servlet.GenericServlet
jakarta.servlet.http.HttpServlet
org.springframework.web.servlet.HttpServletBean
org.springframework.web.servlet.FrameworkServlet
org.springframework.web.servlet.DispatcherServlet
All Implemented Interfaces:
Servlet, ServletConfig, Serializable, org.springframework.beans.factory.Aware, org.springframework.context.ApplicationContextAware, org.springframework.context.EnvironmentAware, org.springframework.core.env.EnvironmentCapable
public class DispatcherServlet extends FrameworkServlet
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.

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:

  • It is based around a JavaBeans configuration mechanism.
  • It can use any HandlerMapping implementation - pre-built or provided as part of an application - to control the routing of requests to handler objects. Default is BeanNameUrlHandlerMapping and RequestMappingHandlerMapping. 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).
  • It can use any HandlerAdapter; this allows for using any handler interface. Default adapters are HttpRequestHandlerAdapter, SimpleControllerHandlerAdapter, for Spring's HttpRequestHandler and Controller interfaces, respectively. A default RequestMappingHandlerAdapter 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).
  • The dispatcher's exception resolution strategy can be specified via a HandlerExceptionResolver, for example mapping certain exceptions to error pages. Default are ExceptionHandlerExceptionResolver, ResponseStatusExceptionResolver, and DefaultHandlerExceptionResolver. These HandlerExceptionResolvers can be overridden through the application context. HandlerExceptionResolver can be given any bean name (they are tested by type).
  • Its view resolution strategy can be specified via a ViewResolver implementation, resolving symbolic view names into View objects. Default is 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).
  • If a View or view name is not supplied by the user, then the configured RequestToViewNameTranslator will translate the current request into a view name. The corresponding bean name is "viewNameTranslator"; the default is DefaultRequestToViewNameTranslator.
  • The dispatcher's strategy for resolving multipart requests is determined by a MultipartResolver implementation. An implementation for standard Servlet multipart processing is included. The MultipartResolver bean name is "multipartResolver"; default is none.
  • Its locale resolution strategy is determined by a LocaleResolver. Out-of-the-box implementations work via HTTP accept header, cookie, or session. The LocaleResolver bean name is "localeResolver"; default is AcceptHeaderLocaleResolver.
  • Its theme resolution strategy is determined by a ThemeResolver. Implementations for a fixed theme and for cookie and session storage are included. The ThemeResolver bean name is "themeResolver"; default is FixedThemeResolver. Theme support is deprecated as of 6.0 with no direct replacement.

NOTE: The @RequestMapping annotation will only be processed if a corresponding HandlerMapping (for type-level annotations) and/or HandlerAdapter (for method-level annotations) is present in the dispatcher. This is the case by default. However, if you are defining custom HandlerMappings or HandlerAdapters, then you need to make sure that a corresponding custom RequestMappingHandlerMapping and/or RequestMappingHandlerAdapter is defined as well - provided that you intend to use @RequestMapping.

A web application can define any number of DispatcherServlets. 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 ContextLoaderListener, if any, will be shared.

DispatcherServlet may 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 the DispatcherServlet(WebApplicationContext) javadoc for details.

Author:
Rod Johnson, Juergen Hoeller, Rob Harrop, Chris Beams, Rossen Stoyanchev, Sebastien Deleuze
See Also:

  • Field Details

  • Constructor Details

  • Method Details

    • setDetectAllHandlerMappings

      public void setDetectAllHandlerMappings(boolean detectAllHandlerMappings)
      Set whether to detect all HandlerMapping beans in this servlet's context. Otherwise, just a single bean with name "handlerMapping" will be expected.

      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.

    • setDetectAllHandlerAdapters

      public void setDetectAllHandlerAdapters(boolean detectAllHandlerAdapters)
      Set whether to detect all HandlerAdapter beans in this servlet's context. Otherwise, just a single bean with name "handlerAdapter" will be expected.

      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.

    • setDetectAllHandlerExceptionResolvers

      public void setDetectAllHandlerExceptionResolvers(boolean detectAllHandlerExceptionResolvers)
      Set whether to detect all HandlerExceptionResolver beans in this servlet's context. Otherwise, just a single bean with name "handlerExceptionResolver" will be expected.

      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.

    • setDetectAllViewResolvers

      public void setDetectAllViewResolvers(boolean detectAllViewResolvers)
      Set whether to detect all ViewResolver beans in this servlet's context. Otherwise, just a single bean with name "viewResolver" will be expected.

      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.

    • setThrowExceptionIfNoHandlerFound

      public void setThrowExceptionIfNoHandlerFound(boolean throwExceptionIfNoHandlerFound)
      Set whether to throw a NoHandlerFoundException when no Handler was found for this request. This exception can then be caught with a HandlerExceptionResolver or an @ExceptionHandler controller method.

      Note that if DefaultServletHttpRequestHandler is used, then requests will always be forwarded to the default servlet and a NoHandlerFoundException would never be thrown in that case.

      Default is "false", meaning the DispatcherServlet sends a NOT_FOUND error through the Servlet response.

      Since:
      4.0

    • setCleanupAfterInclude

      public void setCleanupAfterInclude(boolean cleanupAfterInclude)
      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).

      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.

    • onRefresh

      protected void onRefresh(org.springframework.context.ApplicationContext context)
      This implementation calls initStrategies(org.springframework.context.ApplicationContext).
      Overrides:
      onRefresh in class FrameworkServlet
      Parameters:
      context - the current WebApplicationContext
      See Also:

    • initStrategies

      protected void initStrategies(org.springframework.context.ApplicationContext context)
      Initialize the strategy objects that this servlet uses.

      May be overridden in subclasses in order to initialize further strategy objects.

    • getThemeSource

      @Deprecated @Nullable public final org.springframework.ui.context.ThemeSource getThemeSource()
      Deprecated.
      Return this servlet's ThemeSource, if any; else return null.

      Default is to return the WebApplicationContext as ThemeSource, provided that it implements the ThemeSource interface.

      Returns:
      the ThemeSource, if any
      See Also:

    • getMultipartResolver

      @Nullable public final org.springframework.web.multipart.MultipartResolver getMultipartResolver()
      Obtain this servlet's MultipartResolver, if any.
      Returns:
      the MultipartResolver used by this servlet, or null if none (indicating that no multipart support is available)

    • getHandlerMappings

      @Nullable public final List<HandlerMapping> getHandlerMappings()
      Return the configured HandlerMapping beans that were detected by type in the WebApplicationContext or initialized based on the default set of strategies from DispatcherServlet.properties.

      Note: This method may return null if invoked prior to onRefresh(ApplicationContext).

      Returns:
      an immutable list with the configured mappings, or null if not initialized yet
      Since:
      5.0

    • getDefaultStrategy

      protected <T> T getDefaultStrategy(org.springframework.context.ApplicationContext context, Class<T> strategyInterface)
      Return the default strategy object for the given strategy interface.

      The default implementation delegates to getDefaultStrategies(org.springframework.context.ApplicationContext, java.lang.Class<T>), expecting a single object in the list.

      Parameters:
      context - the current WebApplicationContext
      strategyInterface - the strategy interface
      Returns:
      the corresponding strategy object
      See Also:

    • getDefaultStrategies

      protected <T> List<T> getDefaultStrategies(org.springframework.context.ApplicationContext context, Class<T> strategyInterface)
      Create a List of default strategy objects for the given strategy interface.

      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.

      Parameters:
      context - the current WebApplicationContext
      strategyInterface - the strategy interface
      Returns:
      the List of corresponding strategy objects

    • createDefaultStrategy

      protected Object createDefaultStrategy(org.springframework.context.ApplicationContext context, Class<?> clazz)
      Create a default strategy.

      The default implementation uses AutowireCapableBeanFactory.createBean(java.lang.Class<T>).

      Parameters:
      context - the current WebApplicationContext
      clazz - the strategy implementation class to instantiate
      Returns:
      the fully configured strategy instance
      See Also:
      • ApplicationContext.getAutowireCapableBeanFactory()
      • AutowireCapableBeanFactory.createBean(java.lang.Class<T>)

    • doService

      protected void doService(HttpServletRequest request, HttpServletResponse response) throws Exception
      Exposes the DispatcherServlet-specific request attributes and delegates to doDispatch(jakarta.servlet.http.HttpServletRequest, jakarta.servlet.http.HttpServletResponse) for the actual dispatching.
      Specified by:
      doService in class FrameworkServlet
      Parameters:
      request - current HTTP request
      response - current HTTP response
      Throws:
      Exception - in case of any kind of processing failure
      See Also:

    • doDispatch

      protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception
      Process the actual dispatching to the handler.

      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.

      All HTTP methods are handled by this method. It's up to HandlerAdapters or handlers themselves to decide which methods are acceptable.

      Parameters:
      request - current HTTP request
      response - current HTTP response
      Throws:
      Exception - in case of any kind of processing failure

    • buildLocaleContext

      protected org.springframework.context.i18n.LocaleContext buildLocaleContext(HttpServletRequest request)
      Build a LocaleContext for the given request, exposing the request's primary locale as current locale.

      The default implementation uses the dispatcher's LocaleResolver to obtain the current locale, which might change during a request.

      Overrides:
      buildLocaleContext in class FrameworkServlet
      Parameters:
      request - current HTTP request
      Returns:
      the corresponding LocaleContext
      See Also:
      • LocaleContextHolder.setLocaleContext(org.springframework.context.i18n.LocaleContext)

    • checkMultipart

      protected HttpServletRequest checkMultipart(HttpServletRequest request) throws org.springframework.web.multipart.MultipartException
      Convert the request into a multipart request, and make multipart resolver available.

      If no multipart resolver is set, simply use the existing request.

      Parameters:
      request - current HTTP request
      Returns:
      the processed request (multipart wrapper if necessary)
      Throws:
      org.springframework.web.multipart.MultipartException
      See Also:
      • MultipartResolver.resolveMultipart(jakarta.servlet.http.HttpServletRequest)

    • cleanupMultipart

      protected void cleanupMultipart(HttpServletRequest request)
      Clean up any resources used by the given multipart request (if any).
      Parameters:
      request - current HTTP request
      See Also:
      • MultipartResolver.cleanupMultipart(org.springframework.web.multipart.MultipartHttpServletRequest)

    • getHandler

      @Nullable protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception
      Return the HandlerExecutionChain for this request.

      Tries all handler mappings in order.

      Parameters:
      request - current HTTP request
      Returns:
      the HandlerExecutionChain, or null if no handler could be found
      Throws:
      Exception

    • noHandlerFound

      protected void noHandlerFound(HttpServletRequest request, HttpServletResponse response) throws Exception
      No handler found → set appropriate HTTP response status.
      Parameters:
      request - current HTTP request
      response - current HTTP response
      Throws:
      Exception - if preparing the response failed

    • getHandlerAdapter

      protected HandlerAdapter getHandlerAdapter(Object handler) throws ServletException
      Return the HandlerAdapter for this handler object.
      Parameters:
      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.

    • processHandlerException

      @Nullable protected ModelAndView processHandlerException(HttpServletRequest request, HttpServletResponse response, @Nullable Object handler, Exception ex) throws Exception
      Determine an error ModelAndView via the registered HandlerExceptionResolvers.
      Parameters:
      request - current HTTP request
      response - current HTTP response
      handler - the executed handler, or null if none chosen at the time of the exception (for example, if multipart resolution failed)
      ex - the exception that got thrown during handler execution
      Returns:
      a corresponding ModelAndView to forward to
      Throws:
      Exception - if no error ModelAndView found

    • render

      protected void render(ModelAndView mv, HttpServletRequest request, HttpServletResponse response) throws Exception
      Render the given ModelAndView.

      This is the last stage in handling a request. It may involve resolving the view by name.

      Parameters:
      mv - the ModelAndView to render
      request - current HTTP servlet request
      response - current HTTP servlet response
      Throws:
      ServletException - if view is missing or cannot be resolved
      Exception - if there's a problem rendering the view

    • getDefaultViewName

      @Nullable protected String getDefaultViewName(HttpServletRequest request) throws Exception
      Translate the supplied request into a default view name.
      Parameters:
      request - current HTTP servlet request
      Returns:
      the view name (or null if no default found)
      Throws:
      Exception - if view name translation failed

    • resolveViewName

      @Nullable protected View resolveViewName(String viewName, @Nullable Map<String,Object> model, Locale locale, HttpServletRequest request) throws Exception
      Resolve the given view name into a View object (to be rendered).

      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.

      Parameters:
      viewName - the name of the view to resolve
      model - the model to be passed to the view
      locale - the current locale
      request - current HTTP servlet request
      Returns:
      the View object, or null if none found
      Throws:
      Exception - if the view cannot be resolved (typically in case of problems creating an actual View object)
      See Also: