org.springframework.webflow.engine.builder.TextToTransitionCriteria Maven / Gradle / Ivy
/*
* Copyright 2002-2006 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.builder;
import org.springframework.binding.convert.ConversionContext;
import org.springframework.binding.convert.ConversionException;
import org.springframework.binding.convert.support.AbstractConverter;
import org.springframework.binding.expression.Expression;
import org.springframework.util.StringUtils;
import org.springframework.webflow.engine.TransitionCriteria;
import org.springframework.webflow.engine.WildcardTransitionCriteria;
import org.springframework.webflow.engine.support.BooleanExpressionTransitionCriteria;
import org.springframework.webflow.engine.support.EventIdTransitionCriteria;
/**
* Converter that takes an encoded string representation and produces a
* corresponding TransitionCriteria object.
*
* This converter supports the following encoded forms:
*
* - "*" - will result in a TransitionCriteria object that matches on
* everything ({@link org.springframework.webflow.engine.WildcardTransitionCriteria})
*
* - "eventId" - will result in a TransitionCriteria object that matches
* given event id ({@link org.springframework.webflow.engine.support.EventIdTransitionCriteria})
*
* - "${...}" - will result in a TransitionCriteria object that evaluates
* given condition, expressed as an expression
* ({@link org.springframework.webflow.engine.support.BooleanExpressionTransitionCriteria})
*
* - "bean:<id>" - will result in usage of a custom TransitionCriteria
* bean implementation.
*
*
* @see org.springframework.webflow.engine.TransitionCriteria
*
* @author Keith Donald
* @author Erwin Vervaet
*/
public class TextToTransitionCriteria extends AbstractConverter {
/**
* Prefix used when the user wants to use a custom TransitionCriteria
* implementation managed by a bean factory.
*/
private static final String BEAN_PREFIX = "bean:";
/**
* Locator to use for loading custom TransitionCriteria beans.
*/
private FlowServiceLocator flowServiceLocator;
/**
* Create a new converter that converts strings to transition criteria
* objects. Custom transition criteria will be looked up using given
* service locator.
*/
public TextToTransitionCriteria(FlowServiceLocator flowServiceLocator) {
this.flowServiceLocator = flowServiceLocator;
}
public Class[] getSourceClasses() {
return new Class[] { String.class };
}
public Class[] getTargetClasses() {
return new Class[] { TransitionCriteria.class };
}
protected Object doConvert(Object source, Class targetClass, ConversionContext context) throws Exception {
String encodedCriteria = (String)source;
if (!StringUtils.hasText(encodedCriteria)
|| WildcardTransitionCriteria.WILDCARD_EVENT_ID.equals(encodedCriteria)) {
return WildcardTransitionCriteria.INSTANCE;
}
else if (flowServiceLocator.getExpressionParser().isDelimitedExpression(encodedCriteria)) {
Expression expression = flowServiceLocator.getExpressionParser().parseExpression(encodedCriteria);
return createBooleanExpressionTransitionCriteria(expression);
}
else if (encodedCriteria.startsWith(BEAN_PREFIX)) {
return flowServiceLocator.getTransitionCriteria(encodedCriteria.substring(BEAN_PREFIX.length()));
}
else {
return createEventIdTransitionCriteria(encodedCriteria);
}
}
/**
* Hook method subclasses can override to return a specialized eventId
* matching transition criteria implementation.
* @param eventId the event id to match
* @return the transition criteria object
* @throws ConversionException when something goes wrong
*/
protected TransitionCriteria createEventIdTransitionCriteria(String eventId) throws ConversionException {
return new EventIdTransitionCriteria(eventId);
}
/**
* Hook method subclasses can override to return a specialized expression
* evaluating transition criteria implementation.
* @param expression the expression to evaluate
* @return the transition criteria object
* @throws ConversionException when something goes wrong
*/
protected TransitionCriteria createBooleanExpressionTransitionCriteria(Expression expression)
throws ConversionException {
return new BooleanExpressionTransitionCriteria(expression);
}
}