org.springframework.webflow.mvc.view

Class AbstractMvcView

java.lang.Object

org.springframework.webflow.mvc.view.AbstractMvcView

All Implemented Interfaces:

View

Direct Known Subclasses:

PortletMvcView, ServletMvcView

public abstract class AbstractMvcView
extends java.lang.Object
implements View

Base view implementation for the Spring Web MVC Servlet and Spring Web MVC Portlet frameworks.

Author:

Keith Donald

Field Summary

Fields inherited from interface org.springframework.webflow.execution.View

RENDER_FRAGMENTS_ATTRIBUTE, USER_EVENT_STATE_ATTRIBUTE

Constructor Summary

Constructors

Constructor and Description
AbstractMvcView(org.springframework.web.servlet.View view, RequestContext requestContext) Creates a new MVC view.

Method Summary

Methods

Modifier and Type	Method and Description
protected void	addDefaultMapping(DefaultMapper mapper, java.lang.String parameter, java.lang.Object model) Adds a DefaultMapping between the given request parameter name and a matching model field.
protected void	addDefaultMappings(DefaultMapper mapper, java.util.Set parameterNames, java.lang.Object model) Add a DefaultMapping instance for all incoming request parameters except those having a special field marker prefix.
protected void	addEmptyValueMapping(DefaultMapper mapper, java.lang.String field, java.lang.Object model) Adds a special DefaultMapping that results in setting the target field on the model to an empty value (typically null).
protected void	addMapping(DefaultMapper mapper, BinderConfiguration.Binding binding, java.lang.Object model) Creates and adds a DefaultMapping for the given BinderConfiguration.Binding.
protected void	addModelBindings(DefaultMapper mapper, java.util.Set parameterNames, java.lang.Object model) Adds a DefaultMapping for every configured view BinderConfiguration.Binding for which there is an incoming request parameter.
protected MappingResults	bind(java.lang.Object model) Causes the model to be populated from information contained in request parameters.
protected java.lang.String	determineEventId(RequestContext context) Obtain the user event from the current flow request.
protected abstract void	doRender(java.util.Map model) Template method subclasses should override to execute the view rendering logic.
protected BinderConfiguration	getBinderConfiguration() Returns the binding configuration that defines how to connect properties of the model to UI elements.
protected ConversionService	getConversionService()
protected java.lang.String	getEventId() Returns the id of the user event being processed.
protected ExpressionParser	getExpressionParser() Returns the EL parser to be used for data binding purposes.
protected java.lang.String	getFieldMarkerPrefix() Returns the prefix that can be used for parameters that mark potentially empty fields.
Event	getFlowEvent() Get the flow event the current state should handle.
protected MappingResults	getMappingResults() Returns the results of binding to the view's model, if model binding has occurred.
protected RequestContext	getRequestContext() Returns the current flow request context.
java.io.Serializable	getUserEventState() A memento holding the results of processing a user event.
protected org.springframework.web.servlet.View	getView() Returns the Spring MVC view to render
boolean	hasFlowEvent() True if a call to View.processUserEvent() raised a flow event the current state should handle.
void	processUserEvent() Process the queued user event.
void	render() Render this view's content.
void	saveState() Saves any state associated with this view out to view scope.
void	setBinderConfiguration(BinderConfiguration binderConfiguration) Sets the configuration describing how this view should bind to its model to access data for rendering.
void	setConversionService(ConversionService conversionService) Sets the service to use to expose formatters for field values.
void	setEventIdParameterName(java.lang.String eventIdParameterName) Sets the name of the request parameter to use to lookup user events signaled by this view.
void	setExpressionParser(ExpressionParser expressionParser) Sets the expression parser to use to parse model expressions.
void	setFieldMarkerPrefix(java.lang.String fieldMarkerPrefix) Specify a prefix that can be used for parameters that mark potentially empty fields, having "prefix + field" as name.
void	setMessageCodesResolver(org.springframework.validation.MessageCodesResolver messageCodesResolver) Set the message codes resolver to use to resolve bind and validation failure message codes.
void	setValidator(org.springframework.validation.Validator validator)
protected boolean	shouldBind(java.lang.Object model, TransitionDefinition transition) Determines if model data binding should be invoked given the Transition that matched the current user event being processed.
protected boolean	shouldValidate(java.lang.Object model, TransitionDefinition transition) Determines if model validation should execute given the Transition that matched the current user event being processed.
java.lang.String	toString()
boolean	userEventQueued() True if there is a user event queued this view should process.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

AbstractMvcView

public AbstractMvcView(org.springframework.web.servlet.View view,
               RequestContext requestContext)

Creates a new MVC view.

Parameters:

view - the Spring MVC view to render

requestContext - the current flow request context

Method Detail

setExpressionParser

public void setExpressionParser(ExpressionParser expressionParser)

Sets the expression parser to use to parse model expressions.

Parameters:

expressionParser - the expression parser

setConversionService

public void setConversionService(ConversionService conversionService)

Sets the service to use to expose formatters for field values.

Parameters:

conversionService - the conversion service

setValidator

public void setValidator(org.springframework.validation.Validator validator)

setBinderConfiguration

public void setBinderConfiguration(BinderConfiguration binderConfiguration)

Sets the configuration describing how this view should bind to its model to access data for rendering.

Parameters:

binderConfiguration - the model binder configuration

setMessageCodesResolver

public void setMessageCodesResolver(org.springframework.validation.MessageCodesResolver messageCodesResolver)

Set the message codes resolver to use to resolve bind and validation failure message codes.

Parameters:

messageCodesResolver - the binding error message code resolver to use

setFieldMarkerPrefix

public void setFieldMarkerPrefix(java.lang.String fieldMarkerPrefix)

Specify a prefix that can be used for parameters that mark potentially empty fields, having "prefix + field" as name. Such a marker parameter is checked by existence: You can send any value for it, for example "visible". This is particularly useful for HTML checkboxes and select options.

Default is "_", for "_FIELD" parameters (e.g. "_subscribeToNewsletter"). Set this to null if you want to turn off the empty field check completely.

HTML checkboxes only send a value when they're checked, so it is not possible to detect that a formerly checked box has just been unchecked, at least not with standard HTML means.

This auto-reset mechanism addresses this deficiency, provided that a marker parameter is sent for each checkbox field, like "_subscribeToNewsletter" for a "subscribeToNewsletter" field. As the marker parameter is sent in any case, the data binder can detect an empty field and automatically reset its value.

setEventIdParameterName

public void setEventIdParameterName(java.lang.String eventIdParameterName)

Sets the name of the request parameter to use to lookup user events signaled by this view. If not specified, the default is _eventId

Parameters:

eventIdParameterName - the event id parameter name

render

public void render()
            throws java.io.IOException

Description copied from interface: View

Render this view's content.

Specified by:

render in interface View

Throws:

java.io.IOException - if an IO Exception occured rendering the view

userEventQueued

public boolean userEventQueued()

Description copied from interface: View

True if there is a user event queued this view should process.

Specified by:

userEventQueued in interface View

Returns:

true if a user event is queued, false if not

processUserEvent

public void processUserEvent()

Description copied from interface: View

Process the queued user event. Should only be called when View.userEventQueued() returns true. After calling this method, a flow event may be raised that should be handled in the Web Flow system.

Specified by:

processUserEvent in interface View

See Also:

View.hasFlowEvent()

getUserEventState

public java.io.Serializable getUserEventState()

Description copied from interface: View

A memento holding the results of processing a user event. Used to allow transient view state such as binding and validation errors to survive a flow execution redirect.

Specified by:

getUserEventState in interface View

Returns:

the serializable user event state object, or null if no event state needs managing

See Also:

View.processUserEvent()

hasFlowEvent

public boolean hasFlowEvent()

Description copied from interface: View

True if a call to View.processUserEvent() raised a flow event the current state should handle. Call View.getFlowEvent() to access the Event.

Specified by:

hasFlowEvent in interface View

Returns:

true if yes, false otherwise

getFlowEvent

public Event getFlowEvent()

Description copied from interface: View

Get the flow event the current state should handle. Returns an Event object when View.hasFlowEvent() returns true. Returns null otherwise.

Specified by:

getFlowEvent in interface View

Returns:

the event, or null if there is no event for the flow system to handle

saveState

public void saveState()

Description copied from interface: View

Saves any state associated with this view out to view scope. Called when exiting a ViewState to allow for any changes applied after postback processing to be captured and reflected when going back. Can be a no-op for views that store no view state.

Specified by:

saveState in interface View

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

getRequestContext

protected RequestContext getRequestContext()

Returns the current flow request context.

Returns:

the flow request context

getView

protected org.springframework.web.servlet.View getView()

Returns the Spring MVC view to render

Returns:

the view

getConversionService

protected ConversionService getConversionService()

Returns:

the configured ConversionService

doRender

protected abstract void doRender(java.util.Map model)
                          throws java.lang.Exception

Template method subclasses should override to execute the view rendering logic.

Parameters:

model - the view model data

Throws:

java.lang.Exception - an exception occurred rendering the view

getEventId

protected java.lang.String getEventId()

Returns the id of the user event being processed.

Returns:

the user event

shouldBind

protected boolean shouldBind(java.lang.Object model,
                 TransitionDefinition transition)

Determines if model data binding should be invoked given the Transition that matched the current user event being processed. Returns true unless the bind attribute of the Transition has been set to false. Subclasses may override.

Parameters:

model - the model data binding would be performed on

transition - the matched transition

Returns:

true if binding should occur, false if not

getMappingResults

protected MappingResults getMappingResults()

Returns the results of binding to the view's model, if model binding has occurred.

Returns:

the binding (mapping) results

getBinderConfiguration

protected BinderConfiguration getBinderConfiguration()

Returns the binding configuration that defines how to connect properties of the model to UI elements.

Returns:

an instance of BinderConfiguration or null.

getExpressionParser

protected ExpressionParser getExpressionParser()

Returns the EL parser to be used for data binding purposes.

Returns:

an instance of ExpressionParser.

getFieldMarkerPrefix

protected java.lang.String getFieldMarkerPrefix()

Returns the prefix that can be used for parameters that mark potentially empty fields.

Returns:

the prefix value.

determineEventId

protected java.lang.String determineEventId(RequestContext context)

Obtain the user event from the current flow request. The default implementation returns the value of the request parameter with name eventIdParameterName. Subclasses may override.

Parameters:

context - the current flow request context

Returns:

the user event that occurred

bind

protected MappingResults bind(java.lang.Object model)

Causes the model to be populated from information contained in request parameters.

If a view has binding configuration then only model fields specified in the binding configuration will be considered. In the absence of binding configuration all request parameters will be used to update matching fields on the model.

Parameters:

model - the model to be updated

Returns:

an instance of MappingResults with information about the results of the binding.

addModelBindings

protected void addModelBindings(DefaultMapper mapper,
                    java.util.Set parameterNames,
                    java.lang.Object model)

Adds a DefaultMapping for every configured view BinderConfiguration.Binding for which there is an incoming request parameter. If there is no matching incoming request parameter, a special mapping is created that will set the target field on the model to an empty value (typically null).

Parameters:

mapper - the mapper to which mappings will be added

parameterNames - the request parameters

model - the model

addMapping

protected void addMapping(DefaultMapper mapper,
              BinderConfiguration.Binding binding,
              java.lang.Object model)

Creates and adds a DefaultMapping for the given BinderConfiguration.Binding. Information such as the model field name, if the field is required, and whether type conversion is needed will be passed on from the binding to the mapping.

Note: with Spring 3 type conversion and formatting now in use in Web Flow, it is no longer necessary to use named converters on binding elements. The preferred approach is to register Spring 3 formatters. Named converters are supported for backwards compatibility only and will not result in use of the Spring 3 type conversion system at runtime.

Parameters:

mapper - the mapper to add the mapping to

binding - the binding element

model - the model

addDefaultMappings

protected void addDefaultMappings(DefaultMapper mapper,
                      java.util.Set parameterNames,
                      java.lang.Object model)

Add a DefaultMapping instance for all incoming request parameters except those having a special field marker prefix. This method is used when binding configuration was not specified on the view.

Parameters:

mapper - the mapper to add mappings to

parameterNames - the request parameter names

model - the model

addEmptyValueMapping

protected void addEmptyValueMapping(DefaultMapper mapper,
                        java.lang.String field,
                        java.lang.Object model)

Adds a special DefaultMapping that results in setting the target field on the model to an empty value (typically null).

Parameters:

mapper - the mapper to add the mapping to

field - the field for which a mapping is to be added

model - the model

addDefaultMapping

protected void addDefaultMapping(DefaultMapper mapper,
                     java.lang.String parameter,
                     java.lang.Object model)

Adds a DefaultMapping between the given request parameter name and a matching model field.

Parameters:

mapper - the mapper to add the mapping to

parameter - the request parameter name

model - the model

shouldValidate

protected boolean shouldValidate(java.lang.Object model,
                     TransitionDefinition transition)

Determines if model validation should execute given the Transition that matched the current user event being processed. Returns true unless the validate attribute of the Transition has been set to false, or model data binding errors occurred and the global validateOnBindingErrors flag is set to false. Subclasses may override.

Parameters:

model - the model data binding would be performed on

transition - the matched transition

Returns:

true if binding should occur, false if not