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.util;
018
019 import java.io.BufferedInputStream;
020 import java.io.IOException;
021 import java.io.InputStream;
022 import java.util.ArrayList;
023 import java.util.Collections;
024 import java.util.List;
025 import java.util.Properties;
026 import java.util.concurrent.ConcurrentHashMap;
027
028 import org.apache.camel.spi.Injector;
029
030 /**
031 * Finder to find factories from the resource classpath, usually <b>META-INF/services/org/apache/camel/</b>.
032 */
033 public class FactoryFinder {
034 protected final ConcurrentHashMap<String, Class> classMap = new ConcurrentHashMap<String, Class>();
035 private final String path;
036
037 public FactoryFinder() {
038 this("META-INF/services/org/apache/camel/");
039 }
040
041 public FactoryFinder(String path) {
042 this.path = path;
043 }
044
045 /**
046 * Creates a new instance of the given key
047 *
048 * @param key is the key to add to the path to find a text file containing
049 * the factory name
050 * @return a newly created instance
051 */
052 public Object newInstance(String key) throws IllegalAccessException, InstantiationException, IOException,
053 ClassNotFoundException {
054 return newInstance(key, (String)null);
055 }
056
057 public Object newInstance(String key, String propertyPrefix) throws IllegalAccessException,
058 InstantiationException, IOException, ClassNotFoundException {
059 Class clazz = findClass(key, propertyPrefix);
060 return clazz.newInstance();
061 }
062
063 public Object newInstance(String key, Injector injector) throws IOException, ClassNotFoundException {
064 return newInstance(key, injector, (String)null);
065 }
066
067 public Object newInstance(String key, Injector injector, String propertyPrefix) throws IOException,
068 ClassNotFoundException {
069 Class<?> type = findClass(key, propertyPrefix);
070 return injector.newInstance(type);
071 }
072
073 public <T> T newInstance(String key, Injector injector, Class<T> expectedType) throws IOException,
074 ClassNotFoundException {
075 return newInstance(key, injector, null, expectedType);
076 }
077
078 public <T> T newInstance(String key, Injector injector, String propertyPrefix, Class<T> expectedType)
079 throws IOException, ClassNotFoundException {
080 Class<?> type = findClass(key, propertyPrefix);
081 Object value = injector.newInstance(type);
082 if (expectedType.isInstance(value)) {
083 return expectedType.cast(value);
084 } else {
085 throw new ClassCastException("Not instanceof " + expectedType.getName() + " value: " + value);
086 }
087 }
088
089 public <T> List<T> newInstances(String key, Injector injector, Class<T> type) throws IOException,
090 ClassNotFoundException {
091 List<Class> list = findClasses(key);
092 List<T> answer = new ArrayList<T>(list.size());
093 answer.add(newInstance(key, injector, type));
094 return answer;
095 }
096
097 public Class findClass(String key) throws ClassNotFoundException, IOException {
098 return findClass(key, null);
099 }
100
101 public Class findClass(String key, String propertyPrefix) throws ClassNotFoundException, IOException {
102 if (propertyPrefix == null) {
103 propertyPrefix = "";
104 }
105
106 Class clazz = (Class)classMap.get(propertyPrefix + key);
107 if (clazz == null) {
108 clazz = newInstance(doFindFactoryProperties(key), propertyPrefix);
109 if (clazz != null) {
110 classMap.put(propertyPrefix + key, clazz);
111 }
112 }
113 return clazz;
114 }
115
116 public List<Class> findClasses(String key) throws ClassNotFoundException, IOException {
117 return findClasses(key, null);
118 }
119
120 public List<Class> findClasses(String key, String propertyPrefix) throws ClassNotFoundException,
121 IOException {
122 // TODO change to support finding multiple classes on the classpath!
123 Class type = findClass(key, propertyPrefix);
124 return Collections.singletonList(type);
125 }
126
127 public String getPath() {
128 return path;
129 }
130
131 private Class newInstance(Properties properties, String propertyPrefix) throws ClassNotFoundException,
132 IOException {
133
134 String className = properties.getProperty(propertyPrefix + "class");
135 if (className == null) {
136 throw new IOException("Expected property is missing: " + propertyPrefix + "class");
137 }
138
139 return ObjectHelper.loadClass(className);
140 }
141
142 private Properties doFindFactoryProperties(String key) throws IOException {
143 String uri = path + key;
144
145 InputStream in = ObjectHelper.loadResourceAsStream(uri);
146 if (in == null) {
147 throw new NoFactoryAvailableException(uri);
148 }
149
150 // lets load the file
151 BufferedInputStream reader = null;
152 try {
153 reader = new BufferedInputStream(in);
154 Properties properties = new Properties();
155 properties.load(reader);
156 return properties;
157 } finally {
158 ObjectHelper.close(reader, key, null);
159 ObjectHelper.close(in, key, null);
160 }
161 }
162
163 }