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.camel.util.CamelContextHelper;
027 import org.slf4j.Logger;
028 import org.slf4j.LoggerFactory;
029
030 /**
031 * The default implementation of {@link ComponentResolver} which tries to find
032 * components by using the URI scheme prefix and searching for a file of the URI
033 * scheme name in the <b>META-INF/services/org/apache/camel/component/</b>
034 * directory on the classpath.
035 *
036 * @version
037 */
038 public class DefaultComponentResolver implements ComponentResolver {
039
040 public static final String RESOURCE_PATH = "META-INF/services/org/apache/camel/component/";
041 private static final Logger LOG = LoggerFactory.getLogger(DefaultComponentResolver.class);
042 private FactoryFinder factoryFinder;
043
044 public Component resolveComponent(String name, CamelContext context) {
045 // lookup in registry first
046 Object bean = null;
047 try {
048 bean = context.getRegistry().lookupByName(name);
049 getLog().debug("Found component: {} in registry: {}", name, bean);
050 } catch (Exception e) {
051 getLog().debug("Ignored error looking up bean: " + name, e);
052 }
053 if (bean != null) {
054 if (bean instanceof Component) {
055 return (Component) bean;
056 } else {
057 // lets use Camel's type conversion mechanism to convert things like CamelContext
058 // and other types into a valid Component
059 Component component = CamelContextHelper.convertTo(context, Component.class, bean);
060 if (component != null) {
061 return component;
062 }
063 }
064 // we do not throw the exception here and try to auto create a component
065 }
066
067 // not in registry then use component factory
068 Class<?> type;
069 try {
070 type = findComponent(name, context);
071 if (type == null) {
072 // not found
073 return null;
074 }
075 } catch (NoFactoryAvailableException e) {
076 return null;
077 } catch (Exception e) {
078 throw new IllegalArgumentException("Invalid URI, no Component registered for scheme: " + name, e);
079 }
080
081 if (getLog().isDebugEnabled()) {
082 getLog().debug("Found component: {} via type: {} via: {}{}", new Object[]{name, type.getName(), factoryFinder.getResourcePath(), name});
083 }
084
085 // create the component
086 if (Component.class.isAssignableFrom(type)) {
087 return (Component) context.getInjector().newInstance(type);
088 } else {
089 throw new IllegalArgumentException("Type is not a Component implementation. Found: " + type.getName());
090 }
091 }
092
093 private Class<?> findComponent(String name, CamelContext context) throws ClassNotFoundException, IOException {
094 if (factoryFinder == null) {
095 factoryFinder = context.getFactoryFinder(RESOURCE_PATH);
096 }
097 return factoryFinder.findClass(name);
098 }
099
100 protected Logger getLog() {
101 return LOG;
102 }
103
104 }