001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.camel.component.bean;
018    
019    import java.lang.annotation.Annotation;
020    import java.lang.reflect.Method;
021    
022    import org.apache.camel.CamelContext;
023    import org.apache.camel.Expression;
024    import org.apache.camel.language.LanguageAnnotation;
025    import org.apache.camel.language.bean.BeanExpression;
026    import org.apache.camel.util.ObjectHelper;
027    
028    /**
029     * @version $Revision: 835082 $
030     */
031    public class BeanAnnotationExpressionFactory extends DefaultAnnotationExpressionFactory {
032    
033        @Override
034        public Expression createExpression(CamelContext camelContext, Annotation annotation, LanguageAnnotation languageAnnotation, Class<?> expressionReturnType) {
035            String beanName = getFromAnnotation(annotation, "ref");
036            String method = getFromAnnotation(annotation, "method");
037    
038            // ref is mandatory
039            ObjectHelper.notEmpty(beanName, "ref", annotation);
040    
041            // method is optional but provide it as null to the bean expression
042            if (ObjectHelper.isEmpty(method)) {
043                method = null;
044            }
045    
046            return new BeanExpression(beanName, method);
047        }
048    
049        protected String getFromAnnotation(Annotation annotation, String attribute) {
050            try {
051                Method method = annotation.getClass().getMethod(attribute);
052                Object value = ObjectHelper.invokeMethod(method, annotation);
053                if (value == null) {
054                    throw new IllegalArgumentException("Cannot determine the " + attribute + " from the annotation: " + annotation);
055                }
056                return value.toString();
057            } catch (NoSuchMethodException e) {
058                throw new IllegalArgumentException("Cannot determine the " + attribute
059                    + " of the annotation: " + annotation + " as it does not have a " + attribute + "() method");
060            }
061        }
062    }
063