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.spi.Language;
026 import org.apache.camel.util.ObjectHelper;
027
028 /**
029 * Default implementation of the {@link AnnotationExpressionFactory}.
030 *
031 * @version $Revision: 724627 $
032 */
033 public class DefaultAnnotationExpressionFactory implements AnnotationExpressionFactory {
034
035 public Expression createExpression(CamelContext camelContext, Annotation annotation, LanguageAnnotation languageAnnotation, Class expressionReturnType) {
036 String languageName = languageAnnotation.language();
037 if (languageName == null) {
038 throw new IllegalArgumentException("Cannot determine the language from the annotation: " + annotation);
039 }
040 Language language = camelContext.resolveLanguage(languageName);
041 if (language == null) {
042 throw new IllegalArgumentException("Cannot find the language: " + languageName + " on the classpath");
043 }
044 String expression = getExpressionFromAnnotation(annotation);
045 return language.createExpression(expression);
046 }
047
048 protected String getExpressionFromAnnotation(Annotation annotation) {
049 // lets try the 'value()' method
050 try {
051 Method method = annotation.getClass().getMethod("value");
052 Object value = ObjectHelper.invokeMethod(method, annotation);
053 if (value == null) {
054 throw new IllegalArgumentException("Cannot determine the expression from the annotation: " + annotation);
055 }
056 return value.toString();
057 } catch (NoSuchMethodException e) {
058 throw new IllegalArgumentException("Cannot determine the expression of the annotation: " + annotation + " as it does not have a value() method");
059 }
060 }
061 }