Package 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:

  • Field Details

    • logger

      protected final org.apache.commons.logging.Log logger
      Logger, for use in subclasses.

  • Constructor Details

  • Method Details

    • getId

      public 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 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 String toString()
      Overrides:
      toString in class Object