001 /**
002 *
003 * Licensed to the Apache Software Foundation (ASF) under one or more
004 * contributor license agreements. See the NOTICE file distributed with
005 * this work for additional information regarding copyright ownership.
006 * The ASF licenses this file to You under the Apache License, Version 2.0
007 * (the "License"); you may not use this file except in compliance with
008 * the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018 package org.apache.camel.impl.converter;
019
020 import org.apache.camel.Converter;
021 import org.apache.camel.impl.CachingInjector;
022 import org.apache.camel.util.ResolverUtil;
023 import org.apache.camel.util.ObjectHelper;
024 import org.apache.commons.logging.Log;
025 import org.apache.commons.logging.LogFactory;
026
027 import java.io.BufferedReader;
028 import java.io.IOException;
029 import java.io.InputStreamReader;
030 import java.lang.reflect.Method;
031 import static java.lang.reflect.Modifier.*;
032 import java.net.URL;
033 import java.util.Enumeration;
034 import java.util.HashSet;
035 import java.util.Set;
036 import java.util.StringTokenizer;
037
038 /**
039 * A class which will auto-discover converter objects and methods to pre-load
040 * the registry of converters on startup
041 *
042 * @version $Revision: 546860 $
043 */
044 public class AnnotationTypeConverterLoader implements TypeConverterLoader {
045 public static final String META_INF_SERVICES = "META-INF/services/org/apache/camel/TypeConverter";
046 private static final transient Log log = LogFactory.getLog(AnnotationTypeConverterLoader.class);
047 private ResolverUtil resolver = new ResolverUtil();
048 private Set<Class> visitedClasses = new HashSet<Class>();
049
050 public void load(TypeConverterRegistry registry) throws Exception {
051 String[] packageNames = findPackageNames();
052 resolver.findAnnotated(Converter.class, packageNames);
053 Set<Class> classes = resolver.getClasses();
054 for (Class type : classes) {
055 if (log.isDebugEnabled()) {
056 log.debug("Loading converter class: " + ObjectHelper.name(type));
057 }
058 loadConverterMethods(registry, type);
059 }
060 }
061
062 /**
063 * Finds the names of the packages to search for on the classpath looking for text files on the classpath
064 * at the @{link #META_INF_SERVICES} location
065 *
066 * @return a collection of packages to search for
067 * @throws IOException
068 */
069 protected String[] findPackageNames() throws IOException {
070 Set<String> packages = new HashSet<String>();
071 findPackages(packages, Thread.currentThread().getContextClassLoader());
072 findPackages(packages, getClass().getClassLoader());
073 return packages.toArray(new String[packages.size()]);
074 }
075
076 protected void findPackages(Set<String> packages, ClassLoader classLoader) throws IOException {
077 Enumeration<URL> resources = classLoader.getResources(META_INF_SERVICES);
078 while (resources.hasMoreElements()) {
079 URL url = resources.nextElement();
080 if (url != null) {
081 BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream()));
082 try {
083 while (true) {
084 String line = reader.readLine();
085 if (line == null) {
086 break;
087 }
088 line = line.trim();
089 if (line.startsWith("#") || line.length() == 0) {
090 continue;
091 }
092 tokenize(packages, line);
093 }
094 }
095 finally {
096 try {
097 reader.close();
098 }
099 catch (IOException e) {
100 log.warn("Caught exception closing stream: " + e, e);
101 }
102 }
103 }
104 }
105 }
106
107 /**
108 * Tokenizes the line from the META-IN/services file using commas and ignoring whitespace between packages
109 */
110 protected void tokenize(Set<String> packages, String line) {
111 StringTokenizer iter = new StringTokenizer(line, ",");
112 while (iter.hasMoreTokens()) {
113 String name = iter.nextToken().trim();
114 if (name.length() > 0) {
115 packages.add(name);
116 }
117 }
118 }
119
120 /**
121 * Loads all of the converter methods for the given type
122 */
123 protected void loadConverterMethods(TypeConverterRegistry registry, Class type) {
124 if (visitedClasses.contains(type)) {
125 return;
126 }
127 visitedClasses.add(type);
128 Method[] methods = type.getDeclaredMethods();
129 CachingInjector injector = null;
130
131 for (Method method : methods) {
132 Converter annotation = method.getAnnotation(Converter.class);
133 if (annotation != null) {
134 Class<?>[] parameterTypes = method.getParameterTypes();
135 if (parameterTypes == null || parameterTypes.length != 1) {
136 log.warn("Ignoring bad converter on type: " + type.getName()
137 + " method: " + method + " as a converter method should have one parameter");
138 }
139 else {
140 int modifiers = method.getModifiers();
141 if (isAbstract(modifiers) || !isPublic(modifiers)) {
142 log.warn("Ignoring bad converter on type: " + type.getName()
143 + " method: " + method + " as a converter method is not a public and concrete method");
144 }
145 else {
146 Class toType = method.getReturnType();
147 if (toType.equals(Void.class)) {
148 log.warn("Ignoring bad converter on type: " + type.getName()
149 + " method: " + method + " as a converter method returns a void method");
150 }
151 else {
152 Class fromType = parameterTypes[0];
153 if (isStatic(modifiers)) {
154 registry.addTypeConverter(toType, fromType, new StaticMethodTypeConverter(method));
155 }
156 else {
157 if (injector == null) {
158 injector = new CachingInjector(registry, type);
159 }
160 registry.addTypeConverter(toType, fromType, new InstanceMethodTypeConverter(injector, method));
161 }
162 }
163 }
164 }
165 }
166 }
167 Class superclass = type.getSuperclass();
168 if (superclass != null && !superclass.equals(Object.class)) {
169 loadConverterMethods(registry, superclass);
170 }
171 }
172 }