org.springframework.webflow.engine.DecisionState Maven / Gradle / Ivy
/*
* 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.webflow.execution.FlowExecutionException;
import org.springframework.webflow.execution.RequestContext;
import org.springframework.webflow.execution.ViewSelection;
/**
* A simple transitionable state that when entered will execute the first transition whose matching criteria evaluates
* to true in the {@link RequestContext context} of the current request.
*
* A decision state is a convenient, simple way to encapsulate reusable state transition logic in one place.
*
* @author Keith Donald
*/
public class DecisionState extends TransitionableState {
/**
* Creates a new decision state.
* @param flow the owning flow
* @param stateId the state identifier (must be unique to the flow)
* @throws IllegalArgumentException when this state cannot be added to given flow, e.g. because the id is not unique
*/
public DecisionState(Flow flow, String stateId) throws IllegalArgumentException {
super(flow, stateId);
}
/**
* Specialization of State's doEnter template method that executes behaviour specific to this state
* type in polymorphic fashion.
*
* Simply looks up the first transition that matches the state of the context and executes it.
* @param context the control context for the currently executing flow, used by this state to manipulate the flow
* execution
* @return a view selection containing model and view information needed to render the results of the state
* execution
* @throws FlowExecutionException if an exception occurs in this state
*/
protected ViewSelection doEnter(RequestControlContext context) throws FlowExecutionException {
return getRequiredTransition(context).execute(this, context);
}
}