content: /*
   * 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.camel.component.bean;
  
  import java.lang.annotation.Annotation;
  import java.lang.reflect.Method;
  
  import org.apache.camel.CamelContext;
  import org.apache.camel.Expression;
  import org.apache.camel.spi.Language;
  import org.apache.camel.support.ObjectHelper;
  import org.apache.camel.support.language.DefaultAnnotationExpressionFactory;
  import org.apache.camel.support.language.LanguageAnnotation;
  import org.apache.camel.util.StringHelper;
  
  public class BeanAnnotationExpressionFactory extends DefaultAnnotationExpressionFactory {
  
      @Override
      public Expression createExpression(
              CamelContext camelContext, Annotation annotation, LanguageAnnotation languageAnnotation,
              Class<?> expressionReturnType) {
          String beanName = getFromAnnotation(annotation, "ref");
          String method = getFromAnnotation(annotation, "method");
  
          // ref is mandatory
          StringHelper.notEmpty(beanName, "ref", annotation);
  
          // method is optional but provide it as null to the bean expression
          if (org.apache.camel.util.ObjectHelper.isEmpty(method)) {
              method = null;
          }
  
          Language lan = camelContext.resolveLanguage("bean");
          if (method != null) {
              return lan.createExpression(beanName + "?method=" + method);
          } else {
              return lan.createExpression(beanName);
          }
      }
  
      protected String getFromAnnotation(Annotation annotation, String attribute) {
          try {
              Method method = annotation.annotationType().getDeclaredMethod(attribute);
              Object value = ObjectHelper.invokeMethod(method, annotation);
              if (value == null) {
                  throw new IllegalArgumentException("Cannot determine the " + attribute + " from the annotation: " + annotation);
              }
              return value.toString();
          } catch (NoSuchMethodException e) {
              throw new IllegalArgumentException(
                      "Cannot determine the " + attribute
                                                 + " of the annotation: " + annotation + " as it does not have a " + attribute
                                                 + "() method");
          }
      }
  }
  