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/*
* Copyright 2004-2007 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.webflow.engine;
import org.springframework.core.style.StylerUtils;
import org.springframework.core.style.ToStringCreator;
import org.springframework.webflow.definition.TransitionDefinition;
import org.springframework.webflow.definition.TransitionableStateDefinition;
import org.springframework.webflow.execution.RequestContext;
import org.springframework.webflow.execution.ViewSelection;
/**
* Abstract superclass for states that can execute a transition in response to an event.
*
* @see org.springframework.webflow.engine.Transition
* @see org.springframework.webflow.engine.TransitionCriteria
*
* @author Keith Donald
* @author Erwin Vervaet
*/
public abstract class TransitionableState extends State implements TransitionableStateDefinition {
/**
* The set of possible transitions out of this state.
*/
private TransitionSet transitions = new TransitionSet();
/**
* An actions to execute when exiting this state.
*/
private ActionList exitActionList = new ActionList();
/**
* Create a new transitionable state.
* @param flow the owning flow
* @param id the state identifier (must be unique to the flow)
* @throws IllegalArgumentException when this state cannot be added to given flow, for instance when the id is not
* unique
* @see State#State(Flow, String)
* @see #getTransitionSet()
*/
protected TransitionableState(Flow flow, String id) throws IllegalArgumentException {
super(flow, id);
}
// implementing TranstionableStateDefinition
public TransitionDefinition[] getTransitions() {
return getTransitionSet().toArray();
}
/**
* Returns the set of transitions. The returned set is mutable.
*/
public TransitionSet getTransitionSet() {
return transitions;
}
/**
* Get a transition in this state for given flow execution request context. Throws and exception when there is no
* corresponding transition.
* @throws NoMatchingTransitionException when a matching transition cannot be found
*/
public Transition getRequiredTransition(RequestContext context) throws NoMatchingTransitionException {
Transition transition = getTransitionSet().getTransition(context);
if (transition == null) {
throw new NoMatchingTransitionException(getFlow().getId(), getId(), context.getLastEvent(),
"No transition found on occurence of event '" + context.getLastEvent() + "' in state '" + getId()
+ "' of flow '" + getFlow().getId() + "' -- valid transitional criteria are "
+ StylerUtils.style(getTransitionSet().getTransitionCriterias())
+ " -- likely programmer error, check the set of TransitionCriteria for this state");
}
return transition;
}
/**
* Returns the list of actions executed by this state when it is exited. The returned list is mutable.
* @return the state exit action list
*/
public ActionList getExitActionList() {
return exitActionList;
}
// behavioral methods
/**
* Inform this state definition that an event was signaled in it. The signaled event is the last event available in
* given request context ({@link RequestContext#getLastEvent()}).
* @param context the flow execution control context
* @return the selected view
* @throws NoMatchingTransitionException when a matching transition cannot be found
*/
public ViewSelection onEvent(RequestControlContext context) throws NoMatchingTransitionException {
return getRequiredTransition(context).execute(this, context);
}
/**
* Re-enter this state. This is typically called when a transition out of this state is selected, but transition
* execution rolls back and as a result the flow reenters the source state.
*
* By default, this just calls enter().
* @param context the flow control context in an executing flow (a client instance of a flow)
* @return a view selection containing model and view information needed to render the results of the state
* processing
*/
public ViewSelection reenter(RequestControlContext context) {
return enter(context);
}
/**
* Exit this state. This is typically called when a transition takes the flow out of this state into another state.
* By default just executes any registered exit actions.
* @param context the flow control context
*/
public void exit(RequestControlContext context) {
exitActionList.execute(context);
}
protected void appendToString(ToStringCreator creator) {
creator.append("transitions", transitions).append("exitActionList", exitActionList);
}
}