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 */
017package org.apache.camel.component.bean;
018
019import java.lang.annotation.Annotation;
020import java.lang.reflect.Method;
021
022import org.apache.camel.CamelContext;
023import org.apache.camel.Expression;
024import org.apache.camel.Predicate;
025import org.apache.camel.language.LanguageAnnotation;
026import org.apache.camel.spi.Language;
027import org.apache.camel.util.ObjectHelper;
028import org.apache.camel.util.PredicateToExpressionAdapter;
029
030/**
031 * Default implementation of the {@link AnnotationExpressionFactory}.
032 *
033 * @version 
034 */
035public class DefaultAnnotationExpressionFactory implements AnnotationExpressionFactory {
036
037    public Expression createExpression(CamelContext camelContext, Annotation annotation, LanguageAnnotation languageAnnotation, Class<?> expressionReturnType) {
038        String languageName = languageAnnotation.language();
039        if (languageName == null) {
040            throw new IllegalArgumentException("Cannot determine the language from the annotation: " + annotation);
041        }
042        Language language = camelContext.resolveLanguage(languageName);
043        if (language == null) {
044            throw new IllegalArgumentException("Cannot find the language: " + languageName + " on the classpath");
045        }
046        String expression = getExpressionFromAnnotation(annotation);
047
048        if (expressionReturnType == Boolean.class || expressionReturnType == boolean.class) {
049            Predicate predicate = language.createPredicate(expression);
050            return PredicateToExpressionAdapter.toExpression(predicate);
051        } else {
052            return language.createExpression(expression);
053        }
054    }
055
056    protected String getExpressionFromAnnotation(Annotation annotation) {
057        Object value = getAnnotationObjectValue(annotation, "value");
058        if (value == null) {
059            throw new IllegalArgumentException("Cannot determine the expression from the annotation: " + annotation);
060        }
061        return value.toString();
062    }
063    
064    /**
065     * @param annotation The annotation to get the value of 
066     * @param methodName The annotation name 
067     * @return The value of the annotation
068     */
069    protected Object getAnnotationObjectValue(Annotation annotation, String methodName) {        
070        try {
071            Method method = annotation.getClass().getMethod(methodName);
072            Object value = ObjectHelper.invokeMethod(method, annotation);
073            return value;
074        } catch (NoSuchMethodException e) {
075            throw new IllegalArgumentException("Cannot determine the Object value of the annotation: " + annotation
076                + " as it does not have the method: " + methodName + "() method", e);
077        }
078    }
079}