Spring Framework

org.springframework.web.servlet.mvc.multiaction
Class MultiActionController

java.lang.Object
  extended by org.springframework.context.support.ApplicationObjectSupport
      extended by org.springframework.web.context.support.WebApplicationObjectSupport
          extended by org.springframework.web.servlet.support.WebContentGenerator
              extended by org.springframework.web.servlet.mvc.AbstractController
                  extended by org.springframework.web.servlet.mvc.multiaction.MultiActionController
All Implemented Interfaces:
Aware, ApplicationContextAware, ServletContextAware, Controller, LastModified

public class MultiActionController
extends AbstractController
implements LastModified

Controller implementation that allows multiple request types to be handled by the same class. Subclasses of this class can handle several different types of request with methods of the form

public (ModelAndView | Map | String | void) actionName(HttpServletRequest request, HttpServletResponse response, [,HttpSession] [,AnyObject]);
A Map return value indicates a model that is supposed to be passed to a default view (determined through a RequestToViewNameTranslator). A String return value indicates the name of a view to be rendered without a specific model.

May take a third parameter (of type HttpSession) in which an existing session will be required, or a third parameter of an arbitrary class that gets treated as the command (that is, an instance of the class gets created, and request parameters get bound to it)

These methods can throw any kind of exception, but should only let propagate those that they consider fatal, or which their class or superclass is prepared to catch by implementing an exception handler.

When returning just a Map instance view name translation will be used to generate the view name. The configured RequestToViewNameTranslator will be used to determine the view name.

When returning void a return value of null is assumed meaning that the handler method is responsible for writing the response directly to the supplied HttpServletResponse.

This model allows for rapid coding, but loses the advantage of compile-time checking. It is similar to a Struts DispatchAction, but more sophisticated. Also supports delegation to another object.

An implementation of the MethodNameResolver interface defined in this package should return a method name for a given request, based on any aspect of the request, such as its URL or an "action" parameter. The actual strategy can be configured via the "methodNameResolver" bean property, for each MultiActionController.

The default MethodNameResolver is InternalPathMethodNameResolver; further included strategies are PropertiesMethodNameResolver and ParameterMethodNameResolver.

Subclasses can implement custom exception handler methods with names such as:

public ModelAndView anyMeaningfulName(HttpServletRequest request, HttpServletResponse response, ExceptionClass exception);
The third parameter can be any subclass or Exception or RuntimeException.

There can also be an optional xxxLastModified method for handlers, of signature:

public long anyMeaningfulNameLastModified(HttpServletRequest request)
If such a method is present, it will be invoked. Default return from getLastModified is -1, meaning that the content must always be regenerated.

Note that all handler methods need to be public and that method overloading is not allowed.

See also the description of the workflow performed by the superclass (in that section of the class level Javadoc entitled 'workflow').

Note: For maximum data binding flexibility, consider direct usage of a ServletRequestDataBinder in your controller method, instead of relying on a declared command argument. This allows for full control over the entire binder setup and usage, including the invocation of Validators and the subsequent evaluation of binding/validation errors.

Author:
Rod Johnson, Juergen Hoeller, Colin Sampaleanu, Rob Harrop, Sam Brannen
See Also:
MethodNameResolver, InternalPathMethodNameResolver, PropertiesMethodNameResolver, ParameterMethodNameResolver, LastModified.getLastModified(javax.servlet.http.HttpServletRequest), ServletRequestDataBinder

Field Summary
static java.lang.String DEFAULT_COMMAND_NAME
          Default command name used for binding command objects: "command"
static java.lang.String LAST_MODIFIED_METHOD_SUFFIX
          Suffix for last-modified methods
static java.lang.String PAGE_NOT_FOUND_LOG_CATEGORY
          Log category to use when no mapped handler is found for a request.
protected static org.apache.commons.logging.Log pageNotFoundLogger
          Additional logger to use when no mapped handler is found for a request.
 
Fields inherited from class org.springframework.web.servlet.support.WebContentGenerator
METHOD_GET, METHOD_HEAD, METHOD_POST
 
Fields inherited from class org.springframework.context.support.ApplicationObjectSupport
logger
 
Constructor Summary
MultiActionController()
          Constructor for MultiActionController that looks for handler methods in the present subclass.
MultiActionController(java.lang.Object delegate)
          Constructor for MultiActionController that looks for handler methods in delegate, rather than a subclass of this class.
 
Method Summary
protected  void bind(javax.servlet.http.HttpServletRequest request, java.lang.Object command)
          Bind request parameters onto the given command bean
protected  ServletRequestDataBinder createBinder(javax.servlet.http.HttpServletRequest request, java.lang.Object command)
          Create a new binder instance for the given command and request.
protected  java.lang.String getCommandName(java.lang.Object command)
          Return the command name to use for the given command object.
protected  java.lang.reflect.Method getExceptionHandler(java.lang.Throwable exception)
          Determine the exception handler method for the given exception.
 long getLastModified(javax.servlet.http.HttpServletRequest request)
          Try to find an XXXXLastModified method, where XXXX is the name of a handler.
 MethodNameResolver getMethodNameResolver()
          Return the MethodNameResolver used by this class.
 Validator[] getValidators()
          Return the Validators for this controller.
 WebBindingInitializer getWebBindingInitializer()
          Return the WebBindingInitializer (if any) which will apply pre-configured configuration to every DataBinder that this controller uses.
protected  ModelAndView handleNoSuchRequestHandlingMethod(NoSuchRequestHandlingMethodException ex, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
          Handle the case where no request handler method was found.
protected  ModelAndView handleRequestInternal(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
          Determine a handler method and invoke it.
protected  void initBinder(javax.servlet.http.HttpServletRequest request, ServletRequestDataBinder binder)
          Initialize the given binder instance, for example with custom editors.
protected  ModelAndView invokeNamedMethod(java.lang.String methodName, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
          Invokes the named method.
protected  java.lang.Object newCommandObject(java.lang.Class clazz)
          Create a new command object of the given class.
 void setDelegate(java.lang.Object delegate)
          Set the delegate used by this class; the default is this, assuming that handler methods have been added by a subclass.
 void setMethodNameResolver(MethodNameResolver methodNameResolver)
          Set the method name resolver that this class should use.
 void setValidators(Validator[] validators)
          Set the Validators for this controller.
 void setWebBindingInitializer(WebBindingInitializer webBindingInitializer)
          Specify a WebBindingInitializer which will apply pre-configured configuration to every DataBinder that this controller uses.
 
Methods inherited from class org.springframework.web.servlet.mvc.AbstractController
handleRequest, isSynchronizeOnSession, setSynchronizeOnSession
 
Methods inherited from class org.springframework.web.servlet.support.WebContentGenerator
applyCacheSeconds, applyCacheSeconds, cacheForSeconds, cacheForSeconds, checkAndPrepare, checkAndPrepare, getCacheSeconds, getSupportedMethods, isRequireSession, isUseCacheControlHeader, isUseCacheControlNoStore, isUseExpiresHeader, preventCaching, setCacheSeconds, setRequireSession, setSupportedMethods, setUseCacheControlHeader, setUseCacheControlNoStore, setUseExpiresHeader
 
Methods inherited from class org.springframework.web.context.support.WebApplicationObjectSupport
getServletContext, getTempDir, getWebApplicationContext, initApplicationContext, initServletContext, isContextRequired, setServletContext
 
Methods inherited from class org.springframework.context.support.ApplicationObjectSupport
getApplicationContext, getMessageSourceAccessor, initApplicationContext, requiredContextClass, setApplicationContext
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

LAST_MODIFIED_METHOD_SUFFIX

public static final java.lang.String LAST_MODIFIED_METHOD_SUFFIX
Suffix for last-modified methods

See Also:
Constant Field Values

DEFAULT_COMMAND_NAME

public static final java.lang.String DEFAULT_COMMAND_NAME
Default command name used for binding command objects: "command"

See Also:
Constant Field Values

PAGE_NOT_FOUND_LOG_CATEGORY

public static final java.lang.String PAGE_NOT_FOUND_LOG_CATEGORY
Log category to use when no mapped handler is found for a request.

See Also:
pageNotFoundLogger, Constant Field Values

pageNotFoundLogger

protected static final org.apache.commons.logging.Log pageNotFoundLogger
Additional logger to use when no mapped handler is found for a request.

See Also:
PAGE_NOT_FOUND_LOG_CATEGORY
Constructor Detail

MultiActionController

public MultiActionController()
Constructor for MultiActionController that looks for handler methods in the present subclass.


MultiActionController

public MultiActionController(java.lang.Object delegate)
Constructor for MultiActionController that looks for handler methods in delegate, rather than a subclass of this class.

Parameters:
delegate - handler object. This does not need to implement any particular interface, as everything is done using reflection.
Method Detail

setDelegate

public final void setDelegate(java.lang.Object delegate)
Set the delegate used by this class; the default is this, assuming that handler methods have been added by a subclass.

This method does not get invoked once the class is configured.

Parameters:
delegate - an object containing handler methods
Throws:
java.lang.IllegalStateException - if no handler methods are found

setMethodNameResolver

public final void setMethodNameResolver(MethodNameResolver methodNameResolver)
Set the method name resolver that this class should use.

Allows parameterization of handler method mappings.


getMethodNameResolver

public final MethodNameResolver getMethodNameResolver()
Return the MethodNameResolver used by this class.


setValidators

public final void setValidators(Validator[] validators)
Set the Validators for this controller.

The Validators must support the specified command class.


getValidators

public final Validator[] getValidators()
Return the Validators for this controller.


setWebBindingInitializer

public final void setWebBindingInitializer(WebBindingInitializer webBindingInitializer)
Specify a WebBindingInitializer which will apply pre-configured configuration to every DataBinder that this controller uses.

Allows for factoring out the entire binder configuration to separate objects, as an alternative to initBinder(javax.servlet.http.HttpServletRequest, org.springframework.web.bind.ServletRequestDataBinder).


getWebBindingInitializer

public final WebBindingInitializer getWebBindingInitializer()
Return the WebBindingInitializer (if any) which will apply pre-configured configuration to every DataBinder that this controller uses.


getLastModified

public long getLastModified(javax.servlet.http.HttpServletRequest request)
Try to find an XXXXLastModified method, where XXXX is the name of a handler. Return -1 if there's no such handler, indicating that content must be updated.

Specified by:
getLastModified in interface LastModified
Parameters:
request - current HTTP request
Returns:
the time the underlying resource was last modified, or -1 meaning that the content must always be regenerated
See Also:
LastModified.getLastModified(HttpServletRequest)

handleRequestInternal

protected ModelAndView handleRequestInternal(javax.servlet.http.HttpServletRequest request,
                                             javax.servlet.http.HttpServletResponse response)
                                      throws java.lang.Exception
Determine a handler method and invoke it.

Specified by:
handleRequestInternal in class AbstractController
Throws:
java.lang.Exception
See Also:
MethodNameResolver.getHandlerMethodName(javax.servlet.http.HttpServletRequest), invokeNamedMethod(java.lang.String, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse), handleNoSuchRequestHandlingMethod(org.springframework.web.servlet.mvc.multiaction.NoSuchRequestHandlingMethodException, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)

handleNoSuchRequestHandlingMethod

protected ModelAndView handleNoSuchRequestHandlingMethod(NoSuchRequestHandlingMethodException ex,
                                                         javax.servlet.http.HttpServletRequest request,
                                                         javax.servlet.http.HttpServletResponse response)
                                                  throws java.lang.Exception
Handle the case where no request handler method was found.

The default implementation logs a warning and sends an HTTP 404 error. Alternatively, a fallback view could be chosen, or the NoSuchRequestHandlingMethodException could be rethrown as-is.

Parameters:
ex - the NoSuchRequestHandlingMethodException to be handled
request - current HTTP request
response - current HTTP response
Returns:
a ModelAndView to render, or null if handled directly
Throws:
java.lang.Exception - an Exception that should be thrown as result of the servlet request

invokeNamedMethod

protected final ModelAndView invokeNamedMethod(java.lang.String methodName,
                                               javax.servlet.http.HttpServletRequest request,
                                               javax.servlet.http.HttpServletResponse response)
                                        throws java.lang.Exception
Invokes the named method.

Uses a custom exception handler if possible; otherwise, throw an unchecked exception; wrap a checked exception or Throwable.

Throws:
java.lang.Exception

newCommandObject

protected java.lang.Object newCommandObject(java.lang.Class clazz)
                                     throws java.lang.Exception
Create a new command object of the given class.

This implementation uses BeanUtils.instantiateClass, so commands need to have public no-arg constructors. Subclasses can override this implementation if desired.

Throws:
java.lang.Exception - if the command object could not be instantiated
See Also:
BeanUtils.instantiateClass(Class)

bind

protected void bind(javax.servlet.http.HttpServletRequest request,
                    java.lang.Object command)
             throws java.lang.Exception
Bind request parameters onto the given command bean

Parameters:
request - request from which parameters will be bound
command - command object, that must be a JavaBean
Throws:
java.lang.Exception - in case of invalid state or arguments

createBinder

protected ServletRequestDataBinder createBinder(javax.servlet.http.HttpServletRequest request,
                                                java.lang.Object command)
                                         throws java.lang.Exception
Create a new binder instance for the given command and request.

Called by bind. Can be overridden to plug in custom ServletRequestDataBinder subclasses.

The default implementation creates a standard ServletRequestDataBinder, and invokes initBinder. Note that initBinder will not be invoked if you override this method!

Parameters:
request - current HTTP request
command - the command to bind onto
Returns:
the new binder instance
Throws:
java.lang.Exception - in case of invalid state or arguments
See Also:
bind(javax.servlet.http.HttpServletRequest, java.lang.Object), initBinder(javax.servlet.http.HttpServletRequest, org.springframework.web.bind.ServletRequestDataBinder)

getCommandName

protected java.lang.String getCommandName(java.lang.Object command)
Return the command name to use for the given command object.

Default is "command".

Parameters:
command - the command object
Returns:
the command name to use
See Also:
DEFAULT_COMMAND_NAME

initBinder

protected void initBinder(javax.servlet.http.HttpServletRequest request,
                          ServletRequestDataBinder binder)
                   throws java.lang.Exception
Initialize the given binder instance, for example with custom editors. Called by createBinder.

This method allows you to register custom editors for certain fields of your command class. For instance, you will be able to transform Date objects into a String pattern and back, in order to allow your JavaBeans to have Date properties and still be able to set and display them in an HTML interface.

The default implementation is empty.

Note: the command object is not directly passed to this method, but it's available via DataBinder.getTarget()

Parameters:
request - current HTTP request
binder - new binder instance
Throws:
java.lang.Exception - in case of invalid state or arguments
See Also:
createBinder(javax.servlet.http.HttpServletRequest, java.lang.Object), DataBinder.registerCustomEditor(java.lang.Class, java.beans.PropertyEditor), CustomDateEditor

getExceptionHandler

protected java.lang.reflect.Method getExceptionHandler(java.lang.Throwable exception)
Determine the exception handler method for the given exception.

Can return null if not found.

Parameters:
exception - the exception to handle
Returns:
a handler for the given exception type, or null

Spring Framework