/*
* $Id: ELAttributeEvaluator.java 734389 2009-01-14 13:38:06Z apetrelli $
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.tiles.evaluator.el;
import java.util.Map;
import javax.el.ArrayELResolver;
import javax.el.BeanELResolver;
import javax.el.CompositeELResolver;
import javax.el.ELResolver;
import javax.el.ExpressionFactory;
import javax.el.ListELResolver;
import javax.el.MapELResolver;
import javax.el.ResourceBundleELResolver;
import javax.el.ValueExpression;
import org.apache.tiles.TilesApplicationContext;
import org.apache.tiles.awareness.TilesApplicationContextAware;
import org.apache.tiles.context.TilesRequestContext;
import org.apache.tiles.evaluator.AbstractAttributeEvaluator;
import org.apache.tiles.reflect.ClassUtil;
/**
* Evaluates string expression with typical EL syntax.<br>
* You can use normal EL syntax, knowing that the root objects are
* {@link TilesRequestContext}, {@link TilesApplicationContext} and beans
* contained in request, session and application scope.
*
* @version $Rev: 734389 $ $Date: 2009-01-14 14:38:06 +0100 (mer, 14 gen 2009) $
* @since 2.1.0
*/
public class ELAttributeEvaluator extends AbstractAttributeEvaluator implements
TilesApplicationContextAware {
/**
* Initialization parameter to decide the implementation of
* {@link ExpressionFactoryFactory}.
*
* @since 2.1.0
*/
public static final String EXPRESSION_FACTORY_FACTORY_INIT_PARAM =
"org.apache.tiles.evaluator.el.ExpressionFactoryFactory";
/**
* The Tiles application context.
*
* @since 2.1.0
*/
protected TilesApplicationContext applicationContext;
/**
* The EL expression factory.
*
* @since 2.1.0
*/
protected ExpressionFactory expressionFactory;
/**
* The EL resolver to use.
*
* @since 2.1.0
*/
protected ELResolver resolver;
/**
* Constructor.
*
* @since 2.1.0
*/
public ELAttributeEvaluator() {
}
/** {@inheritDoc} */
public void init(Map<String, String> initParameters) {
String expressionFactoryClassName = initParameters
.get(EXPRESSION_FACTORY_FACTORY_INIT_PARAM);
ExpressionFactoryFactory efFactory;
if (expressionFactoryClassName != null) {
efFactory = (ExpressionFactoryFactory) ClassUtil
.instantiate(expressionFactoryClassName);
} else {
efFactory = (ExpressionFactoryFactory) ClassUtil
.instantiate(
"org.apache.tiles.evaluator.el.JspExpressionFactoryFactory", true);
if (efFactory == null) {
efFactory = new TomcatExpressionFactoryFactory();
}
}
if (efFactory instanceof TilesApplicationContextAware) {
((TilesApplicationContextAware) efFactory)
.setApplicationContext(applicationContext);
}
expressionFactory = efFactory.getExpressionFactory();
resolver = new CompositeELResolver() {
{
add(new TilesContextELResolver());
add(new TilesContextBeanELResolver());
add(new ArrayELResolver(false));
add(new ListELResolver(false));
add(new MapELResolver(false));
add(new ResourceBundleELResolver());
add(new BeanELResolver(false));
}
};
}
/** {@inheritDoc} */
public void setApplicationContext(TilesApplicationContext applicationContext) {
this.applicationContext = applicationContext;
}
/**
* Sets the expression factory to use.
*
* @param expressionFactory The expression factory.
* @since 2.1.0
*/
public void setExpressionFactory(ExpressionFactory expressionFactory) {
this.expressionFactory = expressionFactory;
}
/**
* Sets the EL resolver to use.
*
* @param resolver The EL resolver.
* @since 2.1.0
*/
public void setResolver(ELResolver resolver) {
this.resolver = resolver;
}
/** {@inheritDoc} */
public Object evaluate(String expression, TilesRequestContext request) {
ELContextImpl context = new ELContextImpl(resolver);
context.putContext(TilesRequestContext.class, request);
context.putContext(TilesApplicationContext.class,
applicationContext);
ValueExpression valueExpression = expressionFactory
.createValueExpression(context, expression, Object.class);
return valueExpression.getValue(context);
}
}