org.shept.org.springframework.web.servlet.mvc.delegation

Class DelegatingController

java.lang.Object

org.springframework.context.support.ApplicationObjectSupport

org.springframework.web.context.support.WebApplicationObjectSupport

org.springframework.web.servlet.support.WebContentGenerator

org.springframework.web.servlet.mvc.AbstractController

org.shept.org.springframework.web.servlet.mvc.delegation.DelegatingController

All Implemented Interfaces:

org.springframework.beans.factory.BeanNameAware, org.springframework.beans.factory.InitializingBean, org.springframework.context.ApplicationContextAware, org.springframework.web.context.ServletContextAware, org.springframework.web.servlet.mvc.Controller, org.springframework.web.servlet.mvc.LastModified

Direct Known Subclasses:

MultiActionController

public class DelegatingController
extends org.springframework.web.servlet.mvc.AbstractController
implements org.springframework.web.servlet.mvc.LastModified, org.springframework.beans.factory.BeanNameAware, org.springframework.beans.factory.InitializingBean

Controller implementation that allows multiple request types to be handled by the same class. The design is inspired by the org.springframework.web.servlet.mvc.delegating.DelegatingController but there are some important differences. The DelegatingController is specifically designed to support repetitive elements on a WebPage such as Tables, Schedules, Filtering and searching or any combination of these elements and your own custom requirements.

This is accomplished by delegating to predefined handlers aka WebComponent A number of handlers for filters and tables are already predefined and ready to use. By subclassing AbstractComponent and implementing the WebComponent you can extend the controller with custom Components.

A component is associated with some part of your command object. To resolve the association between components and your command object your command object needs to implement the SubCommandProvider Interface which will inform the controller about the components it supports. Basically the SubCommandProvider Interface specifies a map of bean pathnames and the (sub-)command objects at the nodes of each pathName. See DefaultCommandObject for an example.

This design is very flexible and allows for infinite extension as elements may repeat an infinte number of times requiring just a single handler to take care of them. A good example is a WebPage where you search for customers and their associated data, e.g. addresses, contracts, history information e.t.c. Its easily possible to expand the searchpage towards the end and so you can group a lot of editable information without writing much code.

Now we need to match a form submission with the component handler in duty. By convention each form submission for a component other than root needs a prefix of the same bean pathname which is returned the SubCommandProvider interface. Two resolvers provide this solution: The ComponentNameResolver will match the the pathname of the associated handler and the form submission. In a second step the WebActionResolver will supply the paramters of the form submission with a WebActionToken gathering all the information from the form submission wrapping it with command object and component in a ComponentToken for further processing by the target handler.

The DelegatingController does not bind request parameters to the command object this has to be done by the invoked handler. 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. All error handling is in the responsibility of the invoked handler

Return values can be a map containing model attributes or ModelAndView or RedirectView objects. If there is no model name or redirect url specified then default values will be provided. The configured RequestToViewNameTranslator will be used to determine the view name. In case of a RedirectView it will use the redirectViewName field which is be default the controllers name which should be by convention servlet pathName so redirected views implement by default the get-after-post strategy.

Author:

Rod Johnson, Juergen Hoeller, Colin Sampaleanu, Rob Harrop, Sam Brannen, Andreas Hahn

See Also:

WebActionResolver, ComponentNameResolver, SubmitActionResolver, LastModified.getLastModified(javax.servlet.http.HttpServletRequest), ServletRequestDataBinder

Field Summary

Fields

Modifier and Type	Field and Description
private WebActionResolver	actionResolver Delegate that knows how to determine method names and submission values from incoming requests
private Class<Object>	commandClass Command class specification
static String	DEFAULT_COMMAND_NAME Default command name used for binding command objects: "command"
private WebComponent[]	delegates components handlers
private String	formView formView - this is the fileName
static String	LAST_MODIFIED_METHOD_SUFFIX Suffix for last-modified methods
static 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.
private String	redirectUrl Redirection url - by default this should be the name of the bean (set via BeanNameAware)
private org.springframework.web.bind.support.WebBindingInitializer	webBindingInitializer Optional strategy for pre-initializing data binding

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

Constructors

Constructor and Description
DelegatingController()

Method Summary

Methods

Modifier and Type	Method and Description
void	afterPropertiesSet()
protected ComponentDataBinder	createBinder(javax.servlet.http.HttpServletRequest request, Object command) Create a new binder instance for the given command and request.
protected String	getCommandName(Object command) Return the command name to use for the given command object.
protected Object	getCommandObject(javax.servlet.http.HttpServletRequest request, Class clazz) Create a new command object of the given class.
String	getFormView()
long	getLastModified(javax.servlet.http.HttpServletRequest request) Try to find an XXXXLastModified method, where XXXX is the name of a handler.
String	getRedirectUrl()
org.springframework.web.bind.support.WebBindingInitializer	getWebBindingInitializer() Return the WebBindingInitializer (if any) which will apply pre-configured configuration to every DataBinder that this controller uses.
protected org.springframework.web.servlet.ModelAndView	handleNoSuchRequestHandlingMethod(org.springframework.web.servlet.mvc.multiaction.NoSuchRequestHandlingMethodException ex, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Handle the case where no request handler method was found.
protected org.springframework.web.servlet.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, ComponentDataBinder binder) Initialize the given binder instance, for example with custom editors.
protected org.springframework.web.servlet.ModelAndView	massageReturnValueIfNecessary(Object returnValue) Processes the return value of a handler method to ensure that it either returns null or an instance of ModelAndView.
protected void	postProcessModel(javax.servlet.http.HttpServletRequest request, org.springframework.web.servlet.ModelAndView modelAndView)
private Map<String,Object>	prepareComponentPathForLookup(Map<String,Object> components) put a colon '.' at the end of non empty pathNames
void	setActionResolver(WebActionResolver actionResolver)
void	setBeanName(String name)
void	setCommandClass(Class<Object> commandClass)
void	setDelegates(WebComponent[] delegates)
void	setFormView(String formView)
void	setRedirectUrl(String viewName)
void	setWebBindingInitializer(org.springframework.web.bind.support.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 String LAST_MODIFIED_METHOD_SUFFIX

Suffix for last-modified methods

See Also:

Constant Field Values

DEFAULT_COMMAND_NAME

public static final 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 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

actionResolver

private WebActionResolver actionResolver

Delegate that knows how to determine method names and submission values from incoming requests

webBindingInitializer

private org.springframework.web.bind.support.WebBindingInitializer webBindingInitializer

Optional strategy for pre-initializing data binding

delegates

private WebComponent[] delegates

components handlers

redirectUrl

private String redirectUrl

Redirection url - by default this should be the name of the bean (set via BeanNameAware)

formView

private String formView

formView - this is the fileName

commandClass

private Class<Object> commandClass

Command class specification

Constructor Detail

DelegatingController

public DelegatingController()

Method Detail

setActionResolver

public void setActionResolver(WebActionResolver actionResolver)

Parameters:

actionResolver - the actionResolver to set

setDelegates

public void setDelegates(WebComponent[] delegates)

Parameters:

delegates - the delegates to set

setCommandClass

public void setCommandClass(Class<Object> commandClass)

Parameters:

commandClass - the commandClass to set

setWebBindingInitializer

public final void setWebBindingInitializer(org.springframework.web.bind.support.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.shept.org.springframework.web.bind.support.ComponentDataBinder).

getWebBindingInitializer

public final org.springframework.web.bind.support.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 org.springframework.web.servlet.mvc.LastModified

See Also:

LastModified.getLastModified(HttpServletRequest)

handleRequestInternal

protected org.springframework.web.servlet.ModelAndView handleRequestInternal(javax.servlet.http.HttpServletRequest request,
                                                                 javax.servlet.http.HttpServletResponse response)
                                                                      throws Exception

Determine a handler method and invoke it.

Specified by:

handleRequestInternal in class org.springframework.web.servlet.mvc.AbstractController

Throws:

Exception

See Also:

MethodNameResolver.getHandlerMethodName(javax.servlet.http.HttpServletRequest), #invokeNamedMethod, handleNoSuchRequestHandlingMethod(org.springframework.web.servlet.mvc.multiaction.NoSuchRequestHandlingMethodException, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)

prepareComponentPathForLookup

private Map<String,Object> prepareComponentPathForLookup(Map<String,Object> components)

put a colon '.' at the end of non empty pathNames

Parameters:

-

componentPathName -

pathNames -

Returns:

handleNoSuchRequestHandlingMethod

protected org.springframework.web.servlet.ModelAndView handleNoSuchRequestHandlingMethod(org.springframework.web.servlet.mvc.multiaction.NoSuchRequestHandlingMethodException ex,
                                                                             javax.servlet.http.HttpServletRequest request,
                                                                             javax.servlet.http.HttpServletResponse response)
                                                                                  throws 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:

Exception - an Exception that should be thrown as result of the servlet request

massageReturnValueIfNecessary

protected org.springframework.web.servlet.ModelAndView massageReturnValueIfNecessary(Object returnValue)

Processes the return value of a handler method to ensure that it either returns null or an instance of ModelAndView. When returning a Map, the Map instance is wrapped in a new ModelAndView instance.

getCommandObject

protected Object getCommandObject(javax.servlet.http.HttpServletRequest request,
                      Class clazz)
                           throws 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:

Exception - if the command object could not be instantiated

See Also:

BeanUtils.instantiateClass(Class)

createBinder

protected ComponentDataBinder createBinder(javax.servlet.http.HttpServletRequest request,
                               Object command)
                                    throws 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:

Exception - in case of invalid state or arguments

See Also:

#bind, initBinder(javax.servlet.http.HttpServletRequest, org.shept.org.springframework.web.bind.support.ComponentDataBinder)

getCommandName

protected String getCommandName(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,
              ComponentDataBinder binder)
                   throws 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:

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

postProcessModel

protected void postProcessModel(javax.servlet.http.HttpServletRequest request,
                    org.springframework.web.servlet.ModelAndView modelAndView)
                         throws Exception

Throws:

Exception

setBeanName

public void setBeanName(String name)

Specified by:

setBeanName in interface org.springframework.beans.factory.BeanNameAware

getRedirectUrl

public String getRedirectUrl()

Returns:

the viewName

setRedirectUrl

public void setRedirectUrl(String viewName)

Parameters:

viewName - the viewName to set

afterPropertiesSet

public void afterPropertiesSet()
                        throws Exception

Specified by:

afterPropertiesSet in interface org.springframework.beans.factory.InitializingBean

Throws:

Exception

getFormView

public String getFormView()

Returns:

the formView

setFormView

public void setFormView(String formView)

Parameters:

formView - the formView to set