001 package org.apache.fulcrum.yaafi.framework.interceptor;
002
003 /*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements. See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership. The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License. You may obtain a copy of the License at
011 *
012 * http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied. See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022 import java.lang.reflect.InvocationHandler;
023 import java.lang.reflect.Proxy;
024 import java.util.List;
025
026 import org.apache.avalon.framework.service.ServiceException;
027 import org.apache.avalon.framework.service.ServiceManager;
028 import org.apache.fulcrum.yaafi.framework.constant.AvalonYaafiConstants;
029 import org.apache.fulcrum.yaafi.framework.reflection.Clazz;
030 import org.apache.fulcrum.yaafi.framework.util.Validate;
031
032
033 /**
034 * A factory for creating dynamic proxies for Avalon services.
035 *
036 * @author <a href="mailto:siegfried.goeschl@it20one.at">Siegfried Goeschl</a>
037 */
038
039 public class AvalonInterceptorFactory
040 {
041 /**
042 * Creates a dynamic proxy wrapping a service instance.
043 *
044 * @param serviceName the name of the service
045 * @param serviceShorthand the shorthand of the service being intercepted
046 * @param serviceManager the corresponding service manager
047 * @param serviceInterceptorList the list of interceptors to be installed
048 * @param serviceDelegate the service implementation
049 * @return a dynamic proxy
050 * @throws ServiceException an interceptor was not found
051 */
052 public static Object create(
053 String serviceName,
054 String serviceShorthand,
055 ServiceManager serviceManager,
056 String[] serviceInterceptorList,
057 Object serviceDelegate )
058 throws ServiceException
059 {
060 Validate.notEmpty(serviceName,"serviceName");
061 Validate.notEmpty(serviceShorthand,"serviceShorthand");
062 Validate.notNull(serviceManager,"serviceManager");
063 Validate.notNull(serviceInterceptorList,"serviceInterceptorList");
064 Validate.notNull(serviceDelegate,"serviceDelegate");
065
066 Object result = null;
067
068 Class clazz = serviceDelegate.getClass();
069 ClassLoader classLoader = clazz.getClassLoader();
070 List interfaceList = Clazz.getAllInterfaces(clazz);
071
072 // get the service interfaces to avoid lookups
073
074 AvalonInterceptorService[] avalonInterceptorServices = resolve(
075 serviceManager,
076 serviceInterceptorList
077 );
078
079 InvocationHandler invocationHandler = new AvalonInterceptorInvocationHandler(
080 serviceName,
081 serviceShorthand,
082 serviceDelegate,
083 avalonInterceptorServices
084 );
085
086 result = Proxy.newProxyInstance(
087 classLoader,
088 (Class[]) interfaceList.toArray(new Class[interfaceList.size()]),
089 invocationHandler
090 );
091
092 return result;
093 }
094
095 /**
096 * Resolve all interceptor service names to service interfaces.
097 *
098 * @param serviceManager to lookup the services
099 * @param interceptorList the list of service names
100 * @return a list of interceptor services
101 * @throws ServiceException an interceptor service was not found
102 */
103 private static AvalonInterceptorService[] resolve( ServiceManager serviceManager, String[] interceptorList )
104 throws ServiceException
105 {
106 String interceptorServiceName = null;
107 AvalonInterceptorService[] result = new AvalonInterceptorService[interceptorList.length];
108
109 for( int i=0; i<interceptorList.length; i++ )
110 {
111 interceptorServiceName = interceptorList[i];
112 Object currService = serviceManager.lookup(interceptorServiceName);
113
114 if (currService instanceof AvalonInterceptorService)
115 {
116 result[i] = (AvalonInterceptorService) currService;
117 }
118 else
119 {
120 String msg = "The following service is not an AvalonInterceptorService : " + interceptorServiceName;
121 throw new ServiceException(AvalonYaafiConstants.AVALON_CONTAINER_YAAFI,msg);
122 }
123 }
124
125 return result;
126 }
127 }