org.springframework.webflow.engine.builder
Class RefreshableFlowDefinitionHolder

java.lang.Object
  org.springframework.webflow.engine.builder.RefreshableFlowDefinitionHolder

All Implemented Interfaces:

FlowDefinitionHolder

public class RefreshableFlowDefinitionHolder
extends java.lang.Object
implements FlowDefinitionHolder

A flow definition holder that can detect changes on an underlying flow definition resource and refresh that resource automatically.

This class is threadsafe.

Note that this FlowDefinition holder uses a Flow assembler. This is normal since a Flow is a FlowDefinition! This class bridges the abstract world of flow definitions with the concrete world of flow implementations.

Author:

Keith Donald

See Also:

FlowDefinition, Flow, FlowAssembler

Constructor Summary

RefreshableFlowDefinitionHolder(FlowAssembler assembler)
Creates a new refreshable flow definition holder that uses the configured assembler (GOF director) to drive flow assembly, on initial use and on any resource change or refresh.

Method Summary

protected void	assembleFlow() Assemble the held flow definition, delegating to the configured FlowAssembler (director).
protected long	calculateLastModified() Helper that retrieves the last modified date by querying the backing flow resource.
protected FlowBuilder	getFlowBuilder() Returns the flow builder that actually builds the Flow definition.
FlowDefinition	getFlowDefinition() Returns the flow definition held by this holder.
java.lang.String	getFlowDefinitionId() Returns the id of the flow definition held by this holder.
protected long	getLastModified() Returns the last modifed date of the backed flow definition resource.
protected boolean	isAssembled() Returns a flag indicating if this holder has performed and completed flow definition assembly.
protected boolean	isAssembling() Returns a flag indicating if this holder is performing assembly.
void	refresh() Refresh the flow definition held by this holder.
protected void	refreshIfChanged() Reassemble the flow if its underlying resource has changed.

Methods inherited from class java.lang.Object

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

Constructor Detail

RefreshableFlowDefinitionHolder

public RefreshableFlowDefinitionHolder(FlowAssembler assembler)

Creates a new refreshable flow definition holder that uses the configured assembler (GOF director) to drive flow assembly, on initial use and on any resource change or refresh.

Parameters:

assembler - the flow assembler to use

Method Detail

getFlowDefinitionId

public java.lang.String getFlowDefinitionId()

Description copied from interface: FlowDefinitionHolder

Returns the id of the flow definition held by this holder. This is a lightweight method callers may call to obtain the id of the flow without triggering full flow definition assembly (which may be an expensive operation).

Specified by:

getFlowDefinitionId in interface FlowDefinitionHolder

getFlowDefinition

public FlowDefinition getFlowDefinition()
                                 throws FlowDefinitionConstructionException

Description copied from interface: FlowDefinitionHolder

Returns the flow definition held by this holder. Calling this method the first time may trigger flow assembly (which may be expensive).

Specified by:

getFlowDefinition in interface FlowDefinitionHolder

Throws:

FlowDefinitionConstructionException - if there is a problem constructing the target flow definition

refresh

public void refresh()
             throws FlowBuilderException

Description copied from interface: FlowDefinitionHolder

Refresh the flow definition held by this holder. Calling this method typically triggers flow reassembly, which may include a refresh from an externalized resource such as a file.

Specified by:

refresh in interface FlowDefinitionHolder

Throws:

FlowBuilderException

getFlowBuilder

protected FlowBuilder getFlowBuilder()

Returns the flow builder that actually builds the Flow definition.

refreshIfChanged

protected void refreshIfChanged()

Reassemble the flow if its underlying resource has changed.

calculateLastModified

protected long calculateLastModified()

Helper that retrieves the last modified date by querying the backing flow resource.

Returns:

the last modified date, or -1 if it could not be retrieved

getLastModified

protected long getLastModified()

Returns the last modifed date of the backed flow definition resource.

Returns:

the last modified date

assembleFlow

protected void assembleFlow()
                     throws FlowBuilderException

Assemble the held flow definition, delegating to the configured FlowAssembler (director).

Throws:

FlowBuilderException

isAssembled

protected boolean isAssembled()

Returns a flag indicating if this holder has performed and completed flow definition assembly.

isAssembling

protected boolean isAssembling()

Returns a flag indicating if this holder is performing assembly.