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 org.apache.camel.CamelContext;
020 import org.apache.camel.NoFactoryAvailableException;
021 import org.apache.camel.NoSuchLanguageException;
022 import org.apache.camel.spi.FactoryFinder;
023 import org.apache.camel.spi.Language;
024 import org.apache.camel.spi.LanguageResolver;
025 import org.apache.commons.logging.Log;
026 import org.apache.commons.logging.LogFactory;
027
028 /**
029 * Default language resolver that looks for language factories in <b>META-INF/services/org/apache/camel/language/</b> and
030 * language resolvers in <b>META-INF/services/org/apache/camel/language/resolver/</b>.
031 *
032 * @version $Revision: 889642 $
033 */
034 public class DefaultLanguageResolver implements LanguageResolver {
035 public static final String LANGUAGE_RESOURCE_PATH = "META-INF/services/org/apache/camel/language/";
036 public static final String LANGUAGE_RESOLVER_RESOURCE_PATH = LANGUAGE_RESOURCE_PATH + "resolver/";
037
038 private static final transient Log LOG = LogFactory.getLog(DefaultLanguageResolver.class);
039
040 protected FactoryFinder languageFactory;
041 protected FactoryFinder languageResolver;
042
043 @SuppressWarnings("unchecked")
044 public Language resolveLanguage(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 language: " + name + " in registry: " + bean);
051 }
052 } catch (Exception e) {
053 if (getLog().isDebugEnabled()) {
054 getLog().debug("Ignored error looking up bean: " + name + ". Error: " + e);
055 }
056 }
057 if (bean != null) {
058 if (bean instanceof Language) {
059 return (Language)bean;
060 }
061 // we do not throw the exception here and try to auto create a Language from META-INF
062 }
063
064 Class type = null;
065 try {
066 type = findLanguage(name, context);
067 } catch (NoFactoryAvailableException e) {
068 // ignore
069 } catch (Exception e) {
070 throw new IllegalArgumentException("Invalid URI, no Language registered for scheme: " + name, e);
071 }
072
073 if (type != null) {
074 if (Language.class.isAssignableFrom(type)) {
075 return (Language)context.getInjector().newInstance(type);
076 } else {
077 throw new IllegalArgumentException("Resolving language: " + name + " detected type conflict: Not a Language implementation. Found: " + type.getName());
078 }
079 } else {
080 // no specific language found then try fallback
081 return noSpecificLanguageFound(name, context);
082 }
083 }
084
085 @SuppressWarnings("unchecked")
086 protected Language noSpecificLanguageFound(String name, CamelContext context) {
087 Class type = null;
088 try {
089 type = findLanguageResolver("default", context);
090 } catch (NoFactoryAvailableException e) {
091 // ignore
092 } catch (Exception e) {
093 throw new IllegalArgumentException("Invalid URI, no LanguageResolver registered for scheme: " + name, e);
094 }
095 if (type != null) {
096 if (LanguageResolver.class.isAssignableFrom(type)) {
097 LanguageResolver resolver = (LanguageResolver)context.getInjector().newInstance(type);
098 return resolver.resolveLanguage(name, context);
099 } else {
100 throw new IllegalArgumentException("Resolving language: " + name + " detected type conflict: Not a LanguageResolver implementation. Found: " + type.getName());
101 }
102 }
103 throw new NoSuchLanguageException(name);
104 }
105
106 protected Class<?> findLanguage(String name, CamelContext context) throws Exception {
107 if (languageFactory == null) {
108 languageFactory = context.getFactoryFinder(LANGUAGE_RESOURCE_PATH);
109 }
110 return languageFactory.findClass(name);
111 }
112
113 protected Class<?> findLanguageResolver(String name, CamelContext context) throws Exception {
114 if (languageResolver == null) {
115 languageResolver = context.getFactoryFinder(LANGUAGE_RESOLVER_RESOURCE_PATH);
116 }
117 return languageResolver.findClass(name);
118 }
119
120 protected Log getLog() {
121 return LOG;
122 }
123 }