/*
* Copyright 2004-2012 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.util.Assert;
import org.springframework.webflow.engine.TransitionCriteria;
import org.springframework.webflow.execution.RequestContext;
/**
* Transition criteria that tests the value of an expression. The expression is used to express a condition that guards
* transition execution in a web flow. Expressions will be evaluated against the request context. Boolean, string, and
* custom TransitonCriteria evaluation results are supported.
*
* @author Keith Donald
* @author Erwin Vervaet
*/
public class DefaultTransitionCriteria implements TransitionCriteria {
/**
* The expression evaluator to use.
*/
private Expression expression;
/**
* Create a new expression based transition criteria object.
* @param expression the expression evaluator testing the criteria
*/
public DefaultTransitionCriteria(Expression expression) {
Assert.notNull(expression, "The transition criteria expression to test is required");
this.expression = expression;
}
public boolean test(RequestContext context) {
Object result = expression.getValue(context);
if (result == null) {
return false;
} else if (result instanceof Boolean) {
return (Boolean) result;
} else {
String eventId = String.valueOf(result);
return context.getCurrentEvent().getId().equals(eventId);
}
}
public String toString() {
return expression.toString();
}
}