/*
* 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.builder.support;
import org.springframework.binding.convert.converters.Converter;
import org.springframework.binding.expression.Expression;
import org.springframework.binding.expression.ExpressionParser;
import org.springframework.binding.expression.support.FluentParserContext;
import org.springframework.util.StringUtils;
import org.springframework.webflow.engine.TargetStateResolver;
import org.springframework.webflow.engine.builder.FlowBuilderContext;
import org.springframework.webflow.engine.support.DefaultTargetStateResolver;
import org.springframework.webflow.execution.RequestContext;
/**
* Converter that takes an encoded string representation and produces a corresponding {@link TargetStateResolver}
* object.
* <p>
* This converter supports the following encoded forms:
* <ul>
* <li>"stateId" - will result in a TargetStateResolver that always resolves the same state.</li>
* <li>"${stateIdExpression} - will result in a TargetStateResolver that resolves the target state by evaluating an
* expression against the request context. The resolved value can be a target state identifier or a custom
* TargetStateResolver to delegate to.</li>
* </ul>
*
* @author Keith Donald
* @author Erwin Vervaet
*/
class TextToTargetStateResolver implements Converter {
/**
* Context for flow builder services.
*/
private FlowBuilderContext flowBuilderContext;
/**
* Create a new converter that converts strings to transition target state resolver objects. The given conversion
* service will be used to do all necessary internal conversion (e.g. parsing expression strings).
*/
public TextToTargetStateResolver(FlowBuilderContext flowBuilderContext) {
this.flowBuilderContext = flowBuilderContext;
}
public Class<?> getSourceClass() {
return String.class;
}
public Class<?> getTargetClass() {
return TargetStateResolver.class;
}
public Object convertSourceToTargetClass(Object source, Class<?> targetClass) throws Exception {
String targetStateId = (String) source;
if (!StringUtils.hasText(targetStateId)) {
return null;
}
ExpressionParser parser = flowBuilderContext.getExpressionParser();
Expression expression = parser.parseExpression(targetStateId,
new FluentParserContext().template().evaluate(RequestContext.class).expectResult(String.class));
return new DefaultTargetStateResolver(expression);
}
}