Package org.springframework.webflow.engine

Class State

java.lang.Object
org.springframework.webflow.core.AnnotatedObject
org.springframework.webflow.engine.State
All Implemented Interfaces:
Annotated, StateDefinition
Direct Known Subclasses:
EndState, TransitionableState
public abstract class State extends AnnotatedObject implements StateDefinition
A point in a flow where something happens. What happens is determined by a state's type. Standard types of states include action states, view states, subflow states, and end states.

Each state is associated with exactly one owning flow definition. Specializations of this class capture all the configuration information needed for a specific kind of state.

Subclasses should implement the doEnter method to execute the processing that should occur when this state is entered, acting on its configuration information. The ability to plug-in custom state types that execute different behaviors is the classic GoF state pattern.

Equality: Two states are equal if they have the same id and are part of the same flow.

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

    • State

      protected State(Flow flow, String id) throws IllegalArgumentException
      Creates a state for the provided flow identified by the provided id. The id must be locally unique to the owning flow. The state will be automatically added to the flow.
      Parameters:
      flow - the owning flow
      id - the state identifier (must be unique to the flow)
      Throws:
      IllegalArgumentException - if this state cannot be added to the flow, for instance when the provided id is not unique in the owning flow
      See Also:

  • Method Details

    • getOwner

      public FlowDefinition getOwner()
      Description copied from interface: StateDefinition
      Returns the flow definition this state belongs to.
      Specified by:
      getOwner in interface StateDefinition
      Returns:
      the owning flow definition

    • getId

      public String getId()
      Description copied from interface: StateDefinition
      Returns this state's identifier, locally unique to is containing flow definition.
      Specified by:
      getId in interface StateDefinition
      Returns:
      the state identifier

    • isViewState

      public boolean isViewState()
      Description copied from interface: StateDefinition
      Returns true if this state is a view state.
      Specified by:
      isViewState in interface StateDefinition
      Returns:
      true if a view state, false otherwise

    • getFlow

      public Flow getFlow()
      Returns the owning flow.

    • getEntryActionList

      public ActionList getEntryActionList()
      Returns the list of actions executed by this state when it is entered. The returned list is mutable.
      Returns:
      the state entry action list

    • getExceptionHandlerSet

      public FlowExecutionExceptionHandlerSet getExceptionHandlerSet()
      Returns a mutable set of exception handlers, allowing manipulation of how exceptions are handled when thrown within this state.

      Exception handlers are invoked when an exception occurs when this state is entered, and can execute custom exception handling logic as well as select an error view to display.

      Returns:
      the state exception handler set

    • isStartState

      public boolean isStartState()
      Returns a flag indicating if this state is the start state of its owning flow.
      Returns:
      true if the flow is the start state, false otherwise

    • equals

      public boolean equals(Object o)
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • enter

      public final void enter(RequestControlContext context) throws FlowExecutionException
      Enter this state in the provided flow control context. This implementation just calls the doEnter(RequestControlContext) hook method, which should be implemented by subclasses, after executing the entry actions.
      Parameters:
      context - the control context for the currently executing flow, used by this state to manipulate the flow execution
      Throws:
      FlowExecutionException - if an exception occurs in this state

    • doPreEntryActions

      protected void doPreEntryActions(RequestControlContext context) throws FlowExecutionException
      Hook method to execute before running state entry actions upon state entry. Does nothing by default. Subclasses may override.
      Parameters:
      context - the request control context
      Throws:
      FlowExecutionException - if an exception occurs

    • doEnter

      protected abstract void doEnter(RequestControlContext context) throws FlowExecutionException
      Hook method to execute custom behavior as a result of entering this state. By implementing this method subclasses specialize the behavior of the state.
      Parameters:
      context - the control context for the currently executing flow, used by this state to manipulate the flow execution
      Throws:
      FlowExecutionException - if an exception occurs in this state

    • handleException

      public boolean handleException(FlowExecutionException exception, RequestControlContext context)
      Handle an exception that occurred in this state during the context of the current flow execution request.
      Parameters:
      exception - the exception that occurred
      context - the flow execution control context

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • appendToString

      protected void appendToString(org.springframework.core.style.ToStringCreator creator)
      Subclasses may override this hook method to print their internal state to a string. This default implementation does nothing.
      Parameters:
      creator - the toString creator, to print properties to string
      See Also: