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.impl;
018
019 import java.io.IOException;
020
021 import org.apache.camel.CamelContext;
022 import org.apache.camel.Component;
023 import org.apache.camel.NoFactoryAvailableException;
024 import org.apache.camel.spi.ComponentResolver;
025 import org.apache.camel.spi.FactoryFinder;
026 import org.apache.commons.logging.Log;
027 import org.apache.commons.logging.LogFactory;
028
029 /**
030 * The default implementation of {@link ComponentResolver} which tries to find
031 * components by using the URI scheme prefix and searching for a file of the URI
032 * scheme name in the <b>META-INF/services/org/apache/camel/component/</b>
033 * directory on the classpath.
034 *
035 * @version $Revision: 754461 $
036 */
037 public class DefaultComponentResolver implements ComponentResolver {
038
039 public static final String RESOURCE_PATH = "META-INF/services/org/apache/camel/component/";
040 private static final transient Log LOG = LogFactory.getLog(DefaultComponentResolver.class);
041 private FactoryFinder factoryFinder;
042
043 @SuppressWarnings("unchecked")
044 public Component resolveComponent(String name, CamelContext context) {
045 // lookup in registry first
046 Object bean = null;
047 try {
048 bean = context.getRegistry().lookup(name);
049 if (bean != null && getLog().isDebugEnabled()) {
050 getLog().debug("Found component: " + name + " in registry: " + bean);
051 }
052 } catch (Exception e) {
053 getLog().debug("Ignored error looking up bean: " + name, e);
054 }
055 if (bean != null) {
056 if (bean instanceof Component) {
057 return (Component) bean;
058 }
059 // we do not throw the exception here and try to auto create a component
060 }
061
062 // not in registry then use component factory
063 Class type;
064 try {
065 type = findComponent(name, context);
066 if (type == null) {
067 // not found
068 return null;
069 }
070 } catch (NoFactoryAvailableException e) {
071 return null;
072 } catch (Exception e) {
073 throw new IllegalArgumentException("Invalid URI, no Component registered for scheme: " + name, e);
074 }
075
076 if (getLog().isDebugEnabled()) {
077 getLog().debug("Found component: " + name + " via type: " + type.getName() + " via: " + factoryFinder.getResourcePath() + name);
078 }
079
080 // create the component
081 if (Component.class.isAssignableFrom(type)) {
082 return (Component) context.getInjector().newInstance(type);
083 } else {
084 throw new IllegalArgumentException("Type is not a Component implementation. Found: " + type.getName());
085 }
086 }
087
088 private Class findComponent(String name, CamelContext context) throws ClassNotFoundException, IOException {
089 if (factoryFinder == null) {
090 factoryFinder = context.getFactoryFinder(RESOURCE_PATH);
091 }
092 return factoryFinder.findClass(name);
093 }
094
095 protected Log getLog() {
096 return LOG;
097 }
098
099 }