org.springframework.webflow.engine

Class Transition

java.lang.Object

org.springframework.webflow.core.AnnotatedObject

org.springframework.webflow.engine.Transition

All Implemented Interfaces:

Annotated, TransitionDefinition

public class Transition
extends AnnotatedObject
implements TransitionDefinition

A path from one state to another state.

When executed a transition takes a flow execution from its current state, called the source state, to another state, called the target state. A transition may become eligible for execution on the occurrence of an Event from within a transitionable source state.

When an event occurs within this transition's source TransitionableState the determination of the eligibility of this transition is made by a TransitionCriteria object called the matching criteria. If the matching criteria returns true this transition is marked eligible for execution for that event.

Determination as to whether an eligible transition should be allowed to execute is made by a TransitionCriteria object called the execution criteria. If the execution criteria test fails this transition will roll back and reenter its source state. If the execution criteria test succeeds this transition will execute and take the flow to the transition's target state.

The target state of this transition is typically specified at configuration time in a static manner. If the target state of this transition needs to be calculated in a dynamic fashion at runtime configure a TargetStateResolver that supports such calculations.

Author:

Keith Donald, Erwin Vervaet

See Also:

TransitionableState, TransitionCriteria, TargetStateResolver

Field Summary

Fields

Modifier and Type	Field and Description
protected org.apache.commons.logging.Log	logger Logger, for use in subclasses.

Fields inherited from class org.springframework.webflow.core.AnnotatedObject

CAPTION_PROPERTY, DESCRIPTION_PROPERTY

Constructor Summary

Constructors

Constructor and Description
Transition() Create a new transition that always matches and always executes, but its execution does nothing by default.
Transition(TargetStateResolver targetStateResolver) Create a new transition that always matches and always executes, transitioning to the target state calculated by the provided targetStateResolver.
Transition(TransitionCriteria matchingCriteria, TargetStateResolver targetStateResolver) Create a new transition that matches on the specified criteria, transitioning to the target state calculated by the provided targetStateResolver.

Method Summary

Modifier and Type	Method and Description
boolean	canExecute(RequestContext context) Checks if this transition can complete its execution or should be rolled back, given the state of the flow execution request context.
boolean	execute(State sourceState, RequestControlContext context) Execute this state transition.
TransitionCriteria	getExecutionCriteria() Returns the criteria that determine whether or not this transition, once matched, should complete execution or should roll back.
java.lang.String	getId() The identifier of this transition.
TransitionCriteria	getMatchingCriteria() Returns the criteria that determine whether or not this transition matches as eligible for execution.
java.lang.String	getTargetStateId() Returns an identification of the target state of this transition.
TargetStateResolver	getTargetStateResolver() Returns this transition's target state resolver.
boolean	matches(RequestContext context) Checks if this transition is eligible for execution given the state of the provided flow execution request context.
void	setExecutionCriteria(TransitionCriteria executionCriteria) Set the criteria that determine whether or not this transition, once matched, should complete execution or should roll back.
void	setMatchingCriteria(TransitionCriteria matchingCriteria) Set the criteria that determine whether or not this transition matches as eligible for execution.
void	setTargetStateResolver(TargetStateResolver targetStateResolver) Set this transition's target state resolver, to calculate what state to transition to when this transition is executed.
java.lang.String	toString()

Methods inherited from class org.springframework.webflow.core.AnnotatedObject

getAttributes, getCaption, getDescription, setCaption, setDescription

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.springframework.webflow.core.Annotated

getAttributes, getCaption, getDescription

Field Detail

logger

protected final org.apache.commons.logging.Log logger

Logger, for use in subclasses.

Constructor Detail

Transition

public Transition()

Create a new transition that always matches and always executes, but its execution does nothing by default.

See Also:

setMatchingCriteria(TransitionCriteria), setExecutionCriteria(TransitionCriteria), setTargetStateResolver(TargetStateResolver)

Transition

public Transition(TargetStateResolver targetStateResolver)

Create a new transition that always matches and always executes, transitioning to the target state calculated by the provided targetStateResolver.

Parameters:

targetStateResolver - the resolver of the target state of this transition

See Also:

setMatchingCriteria(TransitionCriteria), setExecutionCriteria(TransitionCriteria)

Transition

public Transition(TransitionCriteria matchingCriteria,
                  TargetStateResolver targetStateResolver)

Create a new transition that matches on the specified criteria, transitioning to the target state calculated by the provided targetStateResolver.

Parameters:

matchingCriteria - the criteria for matching this transition

targetStateResolver - the resolver of the target state of this transition

See Also:

setExecutionCriteria(TransitionCriteria)

Method Detail

getId

public java.lang.String getId()

Description copied from interface: TransitionDefinition

The identifier of this transition. This id value should be unique among all other transitions in a set.

Specified by:

getId in interface TransitionDefinition

Returns:

the transition identifier

getTargetStateId

public java.lang.String getTargetStateId()

Description copied from interface: TransitionDefinition

Returns an identification of the target state of this transition. This could be an actual static state id or something more dynamic, like a string representation of an expression evaluating the target state id at flow execution time.

Specified by:

getTargetStateId in interface TransitionDefinition

Returns:

the target state identifier

getMatchingCriteria

public TransitionCriteria getMatchingCriteria()

Returns the criteria that determine whether or not this transition matches as eligible for execution.

Returns:

the transition matching criteria

setMatchingCriteria

public void setMatchingCriteria(TransitionCriteria matchingCriteria)

Set the criteria that determine whether or not this transition matches as eligible for execution.

Parameters:

matchingCriteria - the transition matching criteria

getExecutionCriteria

public TransitionCriteria getExecutionCriteria()

Returns the criteria that determine whether or not this transition, once matched, should complete execution or should roll back.

Returns:

the transition execution criteria

setExecutionCriteria

public void setExecutionCriteria(TransitionCriteria executionCriteria)

Set the criteria that determine whether or not this transition, once matched, should complete execution or should roll back.

Parameters:

executionCriteria - the transition execution criteria

getTargetStateResolver

public TargetStateResolver getTargetStateResolver()

Returns this transition's target state resolver.

setTargetStateResolver

public void setTargetStateResolver(TargetStateResolver targetStateResolver)

Set this transition's target state resolver, to calculate what state to transition to when this transition is executed.

Parameters:

targetStateResolver - the target state resolver

matches

public boolean matches(RequestContext context)

Checks if this transition is eligible for execution given the state of the provided flow execution request context.

Parameters:

context - the flow execution request context

Returns:

true if this transition should execute, false otherwise

canExecute

public boolean canExecute(RequestContext context)

Checks if this transition can complete its execution or should be rolled back, given the state of the flow execution request context.

Parameters:

context - the flow execution request context

Returns:

true if this transition can complete execution, false if it should roll back

execute

public boolean execute(State sourceState,
                       RequestControlContext context)
                throws FlowExecutionException

Execute this state transition. Should only be called if the matches(RequestContext) method returns true for the given context.

Parameters:

sourceState - the source state to transition from, may be null if the current state is null

context - the flow execution control context

Returns:

a boolean indicating if executing this transition caused the current state to exit and a new state to enter

Throws:

FlowExecutionException - when transition execution fails

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object