/*
* Copyright 2004-2008 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.support;
import org.springframework.binding.expression.Expression;
import org.springframework.binding.expression.support.StaticExpression;
import org.springframework.util.Assert;
import org.springframework.webflow.engine.Flow;
import org.springframework.webflow.engine.State;
import org.springframework.webflow.engine.TargetStateResolver;
import org.springframework.webflow.engine.Transition;
import org.springframework.webflow.execution.RequestContext;
/**
* A transition target state resolver that evaluates an expression to resolve the target state. The default
* implementation.
*
* @author Keith Donald
*/
public class DefaultTargetStateResolver implements TargetStateResolver {
/**
* The expression for the target state identifier.
*/
private Expression targetStateIdExpression;
/**
* Creates a new target state resolver that always returns the same target state id.
* @param targetStateId a static target target state
*/
public DefaultTargetStateResolver(String targetStateId) {
this(new StaticExpression(targetStateId));
}
/**
* Creates a new target state resolver.
* @param targetStateIdExpression the target state expression
*/
public DefaultTargetStateResolver(Expression targetStateIdExpression) {
Assert.notNull(targetStateIdExpression, "The target state id expression is required");
this.targetStateIdExpression = targetStateIdExpression;
}
public State resolveTargetState(Transition transition, State sourceState, RequestContext context) {
String targetStateId = (String) targetStateIdExpression.getValue(context);
if (targetStateId != null) {
return ((Flow) context.getActiveFlow()).getStateInstance(targetStateId);
} else {
return null;
}
}
public String toString() {
return targetStateIdExpression.toString();
}
}