public class DispatcherServlet extends FrameworkServlet
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:
HandlerMapping
implementation - pre-built or provided as part
of an application - to control the routing of requests to handler objects. Default is
BeanNameUrlHandlerMapping
and
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).
HandlerAdapter
; this allows for using any handler interface.
Default adapters are HttpRequestHandlerAdapter
,
SimpleControllerHandlerAdapter
, for Spring's
HttpRequestHandler
and
Controller
interfaces, respectively. A default
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).
HandlerExceptionResolver
, for example mapping certain exceptions to error pages.
Default are
AnnotationMethodHandlerExceptionResolver
,
ResponseStatusExceptionResolver
, and
DefaultHandlerExceptionResolver
.
These HandlerExceptionResolvers can be overridden through the application context.
HandlerExceptionResolver can be given any bean name (they are tested by type).
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).
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
.
MultipartResolver
implementation.
Implementations for Apache Commons FileUpload and Servlet 3 are included; the typical
choice is CommonsMultipartResolver
.
The MultipartResolver bean name is "multipartResolver"; default is none.
LocaleResolver
.
Out-of-the-box implementations work via HTTP accept header, cookie, or session.
The LocaleResolver bean name is "localeResolver"; default is
AcceptHeaderLocaleResolver
.
ThemeResolver
.
Implementations for a fixed theme and for cookie and session storage are included.
The ThemeResolver bean name is "themeResolver"; default is
FixedThemeResolver
.
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
DefaultAnnotationHandlerMapping
and/or AnnotationMethodHandlerAdapter
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.
As of Spring 3.1, 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 the DispatcherServlet(WebApplicationContext)
javadoc for details.
HttpRequestHandler
,
Controller
,
ContextLoaderListener
,
Serialized FormModifier and Type | Field and Description |
---|---|
static String |
EXCEPTION_ATTRIBUTE
Name of request attribute that exposes an Exception resolved with an
HandlerExceptionResolver but where no view was rendered
(e.g. |
static String |
FLASH_MAP_MANAGER_ATTRIBUTE
Name of request attribute that holds the
FlashMapManager . |
static String |
FLASH_MAP_MANAGER_BEAN_NAME
Well-known name for the FlashMapManager object in the bean factory for this namespace.
|
static String |
HANDLER_ADAPTER_BEAN_NAME
Well-known name for the HandlerAdapter object in the bean factory for this namespace.
|
static String |
HANDLER_EXCEPTION_RESOLVER_BEAN_NAME
Well-known name for the HandlerExceptionResolver object in the bean factory for this namespace.
|
static String |
HANDLER_MAPPING_BEAN_NAME
Well-known name for the HandlerMapping object in the bean factory for this namespace.
|
static String |
INPUT_FLASH_MAP_ATTRIBUTE
Name of request attribute that holds a read-only
Map<String,?>
with "input" flash attributes saved by a previous request, if any. |
static String |
LOCALE_RESOLVER_ATTRIBUTE
Request attribute to hold the current LocaleResolver, retrievable by views.
|
static String |
LOCALE_RESOLVER_BEAN_NAME
Well-known name for the LocaleResolver object in the bean factory for this namespace.
|
static String |
MULTIPART_RESOLVER_BEAN_NAME
Well-known name for the MultipartResolver object in the bean factory for this namespace.
|
static String |
OUTPUT_FLASH_MAP_ATTRIBUTE
Name of request attribute that holds the "output"
FlashMap with
attributes to save for a subsequent request. |
static String |
PAGE_NOT_FOUND_LOG_CATEGORY
Log category to use when no mapped handler is found for a request.
|
protected static Log |
pageNotFoundLogger
Additional logger to use when no mapped handler is found for a request.
|
static String |
REQUEST_TO_VIEW_NAME_TRANSLATOR_BEAN_NAME
Well-known name for the RequestToViewNameTranslator object in the bean factory for this namespace.
|
static String |
THEME_RESOLVER_ATTRIBUTE
Request attribute to hold the current ThemeResolver, retrievable by views.
|
static String |
THEME_RESOLVER_BEAN_NAME
Well-known name for the ThemeResolver object in the bean factory for this namespace.
|
static String |
THEME_SOURCE_ATTRIBUTE
Request attribute to hold the current ThemeSource, retrievable by views.
|
static String |
VIEW_RESOLVER_BEAN_NAME
Well-known name for the ViewResolver object in the bean factory for this namespace.
|
static String |
WEB_APPLICATION_CONTEXT_ATTRIBUTE
Request attribute to hold the current web application context.
|
DEFAULT_CONTEXT_CLASS, DEFAULT_NAMESPACE_SUFFIX, SERVLET_CONTEXT_PREFIX
logger
Constructor and Description |
---|
DispatcherServlet()
Create a new
DispatcherServlet that will create its own internal web
application context based on defaults and values provided through servlet
init-params. |
DispatcherServlet(WebApplicationContext webApplicationContext)
Create a new
DispatcherServlet with the given web application context. |
Modifier and Type | Method and Description |
---|---|
protected LocaleContext |
buildLocaleContext(HttpServletRequest request)
Build a LocaleContext for the given request, exposing the request's primary locale as current locale.
|
protected HttpServletRequest |
checkMultipart(HttpServletRequest request)
Convert the request into a multipart request, and make multipart resolver available.
|
protected void |
cleanupMultipart(HttpServletRequest request)
Clean up any resources used by the given multipart request (if any).
|
protected Object |
createDefaultStrategy(ApplicationContext context,
Class<?> clazz)
Create a default strategy.
|
protected void |
doDispatch(HttpServletRequest request,
HttpServletResponse response)
Process the actual dispatching to the handler.
|
protected void |
doService(HttpServletRequest request,
HttpServletResponse response)
Exposes the DispatcherServlet-specific request attributes and delegates to
doDispatch(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
for the actual dispatching. |
protected <T> List<T> |
getDefaultStrategies(ApplicationContext context,
Class<T> strategyInterface)
Create a List of default strategy objects for the given strategy interface.
|
protected <T> T |
getDefaultStrategy(ApplicationContext context,
Class<T> strategyInterface)
Return the default strategy object for the given strategy interface.
|
protected String |
getDefaultViewName(HttpServletRequest request)
Translate the supplied request into a default view name.
|
protected HandlerExecutionChain |
getHandler(HttpServletRequest request)
Return the HandlerExecutionChain for this request.
|
protected HandlerAdapter |
getHandlerAdapter(Object handler)
Return the HandlerAdapter for this handler object.
|
MultipartResolver |
getMultipartResolver()
Obtain this servlet's MultipartResolver, if any.
|
ThemeSource |
getThemeSource()
Return this servlet's ThemeSource, if any; else return
null . |
protected void |
initStrategies(ApplicationContext context)
Initialize the strategy objects that this servlet uses.
|
protected void |
noHandlerFound(HttpServletRequest request,
HttpServletResponse response)
No handler found -> set appropriate HTTP response status.
|
protected void |
onRefresh(ApplicationContext context)
This implementation calls
initStrategies(org.springframework.context.ApplicationContext) . |
protected ModelAndView |
processHandlerException(HttpServletRequest request,
HttpServletResponse response,
Object handler,
Exception ex)
Determine an error ModelAndView via the registered HandlerExceptionResolvers.
|
protected void |
render(ModelAndView mv,
HttpServletRequest request,
HttpServletResponse response)
Render the given ModelAndView.
|
protected View |
resolveViewName(String viewName,
Map<String,Object> model,
Locale locale,
HttpServletRequest request)
Resolve the given view name into a View object (to be rendered).
|
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.
|
void |
setDetectAllHandlerAdapters(boolean detectAllHandlerAdapters)
Set whether to detect all HandlerAdapter beans in this servlet's context.
|
void |
setDetectAllHandlerExceptionResolvers(boolean detectAllHandlerExceptionResolvers)
Set whether to detect all HandlerExceptionResolver beans in this servlet's context.
|
void |
setDetectAllHandlerMappings(boolean detectAllHandlerMappings)
Set whether to detect all HandlerMapping beans in this servlet's context.
|
void |
setDetectAllViewResolvers(boolean detectAllViewResolvers)
Set whether to detect all ViewResolver beans in this servlet's context.
|
void |
setThrowExceptionIfNoHandlerFound(boolean throwExceptionIfNoHandlerFound)
Set whether to throw a NoHandlerFoundException when no Handler was found for this request.
|
applyInitializers, buildRequestAttributes, configureAndRefreshWebApplicationContext, createWebApplicationContext, createWebApplicationContext, destroy, doDelete, doGet, doOptions, doPost, doPut, doTrace, findWebApplicationContext, getContextAttribute, getContextClass, getContextConfigLocation, getContextId, getNamespace, getServletContextAttributeName, getUsernameForRequest, getWebApplicationContext, initFrameworkServlet, initServletBean, initWebApplicationContext, onApplicationEvent, postProcessWebApplicationContext, processRequest, refresh, service, setApplicationContext, setContextAttribute, setContextClass, setContextConfigLocation, setContextId, setContextInitializerClasses, setContextInitializers, setDispatchOptionsRequest, setDispatchTraceRequest, setNamespace, setPublishContext, setPublishEvents, setThreadContextInheritable
addRequiredProperty, createEnvironment, getEnvironment, getServletContext, getServletName, init, initBeanWrapper, setEnvironment
doHead, getLastModified, service
getInitParameter, getInitParameterNames, getServletConfig, getServletInfo, init, log, log
public static final String MULTIPART_RESOLVER_BEAN_NAME
public static final String LOCALE_RESOLVER_BEAN_NAME
public static final String THEME_RESOLVER_BEAN_NAME
public static final String HANDLER_MAPPING_BEAN_NAME
public static final String HANDLER_ADAPTER_BEAN_NAME
public static final String HANDLER_EXCEPTION_RESOLVER_BEAN_NAME
public static final String REQUEST_TO_VIEW_NAME_TRANSLATOR_BEAN_NAME
public static final String VIEW_RESOLVER_BEAN_NAME
public static final String FLASH_MAP_MANAGER_BEAN_NAME
public static final String WEB_APPLICATION_CONTEXT_ATTRIBUTE
public static final String LOCALE_RESOLVER_ATTRIBUTE
public static final String THEME_RESOLVER_ATTRIBUTE
public static final String THEME_SOURCE_ATTRIBUTE
public static final String INPUT_FLASH_MAP_ATTRIBUTE
Map<String,?>
with "input" flash attributes saved by a previous request, if any.public static final String OUTPUT_FLASH_MAP_ATTRIBUTE
FlashMap
with
attributes to save for a subsequent request.public static final String FLASH_MAP_MANAGER_ATTRIBUTE
FlashMapManager
.public static final String EXCEPTION_ATTRIBUTE
HandlerExceptionResolver
but where no view was rendered
(e.g. setting the status code).public static final String PAGE_NOT_FOUND_LOG_CATEGORY
protected static final Log pageNotFoundLogger
public DispatcherServlet()
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 web.xml
which requires the use
of a no-arg constructor.
Calling FrameworkServlet.setContextConfigLocation(java.lang.String)
(init-param 'contextConfigLocation')
will dictate which XML files will be loaded by the
default XmlWebApplicationContext
Calling FrameworkServlet.setContextClass(java.lang.Class<?>)
(init-param 'contextClass') overrides the
default XmlWebApplicationContext
and allows for specifying an alternative class,
such as AnnotationConfigWebApplicationContext
.
Calling FrameworkServlet.setContextInitializerClasses(java.lang.String)
(init-param 'contextInitializerClasses')
indicates which ApplicationContextInitializer
classes should be used to
further configure the internal application context prior to refresh().
DispatcherServlet(WebApplicationContext)
public DispatcherServlet(WebApplicationContext webApplicationContext)
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 ServletContext.addServlet(java.lang.String, java.lang.String)
API.
Using this constructor indicates that the following properties / init-params will be ignored:
FrameworkServlet.setContextClass(Class)
/ 'contextClass'FrameworkServlet.setContextConfigLocation(String)
/ 'contextConfigLocation'FrameworkServlet.setContextAttribute(String)
/ 'contextAttribute'FrameworkServlet.setNamespace(String)
/ 'namespace'The given web application context may or may not yet be refreshed. If it has not already been refreshed (the recommended approach), then the following will occur:
ServletContext
and ServletConfig
objects will be delegated to
the application contextFrameworkServlet.postProcessWebApplicationContext(org.springframework.web.context.ConfigurableWebApplicationContext)
will be calledApplicationContextInitializer
s specified through the
"contextInitializerClasses" init-param or through the FrameworkServlet.setContextInitializers(org.springframework.context.ApplicationContextInitializer<?>...)
property will be applied.refresh()
will be called if the
context implements ConfigurableApplicationContext
See WebApplicationInitializer
for usage examples.
webApplicationContext
- the context to useFrameworkServlet.initWebApplicationContext()
,
FrameworkServlet.configureAndRefreshWebApplicationContext(org.springframework.web.context.ConfigurableWebApplicationContext)
,
WebApplicationInitializer
public void setDetectAllHandlerMappings(boolean detectAllHandlerMappings)
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 setDetectAllHandlerAdapters(boolean detectAllHandlerAdapters)
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 setDetectAllHandlerExceptionResolvers(boolean detectAllHandlerExceptionResolvers)
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 setDetectAllViewResolvers(boolean detectAllViewResolvers)
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 setThrowExceptionIfNoHandlerFound(boolean throwExceptionIfNoHandlerFound)
@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.
public void setCleanupAfterInclude(boolean cleanupAfterInclude)
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.
protected void onRefresh(ApplicationContext context)
initStrategies(org.springframework.context.ApplicationContext)
.onRefresh
in class FrameworkServlet
context
- the current WebApplicationContextFrameworkServlet.refresh()
protected void initStrategies(ApplicationContext context)
May be overridden in subclasses in order to initialize further strategy objects.
public final ThemeSource getThemeSource()
null
.
Default is to return the WebApplicationContext as ThemeSource, provided that it implements the ThemeSource interface.
FrameworkServlet.getWebApplicationContext()
public final MultipartResolver getMultipartResolver()
null
if none
(indicating that no multipart support is available)protected <T> T getDefaultStrategy(ApplicationContext context, Class<T> strategyInterface)
The default implementation delegates to getDefaultStrategies(org.springframework.context.ApplicationContext, java.lang.Class<T>)
,
expecting a single object in the list.
context
- the current WebApplicationContextstrategyInterface
- the strategy interfacegetDefaultStrategies(org.springframework.context.ApplicationContext, java.lang.Class<T>)
protected <T> List<T> getDefaultStrategies(ApplicationContext context, Class<T> strategyInterface)
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.
context
- the current WebApplicationContextstrategyInterface
- the strategy interfaceprotected Object createDefaultStrategy(ApplicationContext context, Class<?> clazz)
The default implementation uses
AutowireCapableBeanFactory.createBean(java.lang.Class<T>)
.
context
- the current WebApplicationContextclazz
- the strategy implementation class to instantiateApplicationContext.getAutowireCapableBeanFactory()
,
AutowireCapableBeanFactory.createBean(java.lang.Class<T>)
protected void doService(HttpServletRequest request, HttpServletResponse response) throws Exception
doDispatch(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
for the actual dispatching.doService
in class FrameworkServlet
request
- current HTTP requestresponse
- current HTTP responseException
- in case of any kind of processing failureHttpServlet.doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
,
HttpServlet.doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception
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.
request
- current HTTP requestresponse
- current HTTP responseException
- in case of any kind of processing failureprotected LocaleContext buildLocaleContext(HttpServletRequest request)
The default implementation uses the dispatcher's LocaleResolver to obtain the current locale, which might change during a request.
buildLocaleContext
in class FrameworkServlet
request
- current HTTP requestLocaleContextHolder.setLocaleContext(org.springframework.context.i18n.LocaleContext)
protected HttpServletRequest checkMultipart(HttpServletRequest request) throws MultipartException
If no multipart resolver is set, simply use the existing request.
request
- current HTTP requestMultipartException
MultipartResolver.resolveMultipart(javax.servlet.http.HttpServletRequest)
protected void cleanupMultipart(HttpServletRequest request)
request
- current HTTP requestMultipartResolver.cleanupMultipart(org.springframework.web.multipart.MultipartHttpServletRequest)
protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception
Tries all handler mappings in order.
request
- current HTTP requestnull
if no handler could be foundException
protected void noHandlerFound(HttpServletRequest request, HttpServletResponse response) throws Exception
request
- current HTTP requestresponse
- current HTTP responseException
- if preparing the response failedprotected HandlerAdapter getHandlerAdapter(Object handler) throws ServletException
handler
- the handler object to find an adapter forServletException
- if no HandlerAdapter can be found for the handler. This is a fatal error.protected ModelAndView processHandlerException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception
request
- current HTTP requestresponse
- current HTTP responsehandler
- 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 executionException
- if no error ModelAndView foundprotected void render(ModelAndView mv, HttpServletRequest request, HttpServletResponse response) throws Exception
This is the last stage in handling a request. It may involve resolving the view by name.
mv
- the ModelAndView to renderrequest
- current HTTP servlet requestresponse
- current HTTP servlet responseServletException
- if view is missing or cannot be resolvedException
- if there's a problem rendering the viewprotected String getDefaultViewName(HttpServletRequest request) throws Exception
request
- current HTTP servlet requestnull
if no default found)Exception
- if view name translation failedprotected View resolveViewName(String viewName, Map<String,Object> model, Locale locale, HttpServletRequest request) throws Exception
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.
viewName
- the name of the view to resolvemodel
- the model to be passed to the viewlocale
- the current localerequest
- current HTTP servlet requestnull
if none foundException
- if the view cannot be resolved
(typically in case of problems creating an actual View object)ViewResolver.resolveViewName(java.lang.String, java.util.Locale)