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.converter;
018
019 import java.io.BufferedReader;
020 import java.io.IOException;
021 import java.io.InputStreamReader;
022
023 import java.lang.annotation.Annotation;
024 import java.lang.reflect.Method;
025
026 import java.net.URL;
027 import java.util.Enumeration;
028 import java.util.HashSet;
029 import java.util.Set;
030 import java.util.StringTokenizer;
031 import static java.lang.reflect.Modifier.isAbstract;
032 import static java.lang.reflect.Modifier.isPublic;
033 import static java.lang.reflect.Modifier.isStatic;
034
035 import org.apache.camel.Converter;
036 import org.apache.camel.Exchange;
037 import org.apache.camel.TypeConverter;
038 import org.apache.camel.util.ObjectHelper;
039 import org.apache.camel.util.ResolverUtil;
040 import org.apache.camel.util.WebSphereResolverUtil;
041 import org.apache.commons.logging.Log;
042 import org.apache.commons.logging.LogFactory;
043
044 /**
045 * A class which will auto-discover converter objects and methods to pre-load
046 * the registry of converters on startup
047 *
048 * @version $Revision: 742185 $
049 */
050 public class AnnotationTypeConverterLoader implements TypeConverterLoader {
051 public static final String META_INF_SERVICES = "META-INF/services/org/apache/camel/TypeConverter";
052 private static final transient Log LOG = LogFactory.getLog(AnnotationTypeConverterLoader.class);
053 private ResolverUtil resolver;
054 private Set<Class> visitedClasses = new HashSet<Class>();
055
056 public AnnotationTypeConverterLoader() {
057 // use WebSphere specific resolver if running on WebSphere
058 if (WebSphereResolverUtil.isWebSphereClassLoader(this.getClass().getClassLoader())) {
059 LOG.info("Using WebSphere specific ResolverUtil");
060 resolver = new WebSphereResolverUtil(META_INF_SERVICES);
061 } else {
062 resolver = new ResolverUtil();
063 }
064 }
065
066 public AnnotationTypeConverterLoader(ResolverUtil resolverUtil) {
067 this.resolver = resolverUtil;
068 }
069
070 public void load(TypeConverterRegistry registry) throws Exception {
071 String[] packageNames = findPackageNames();
072 resolver.findAnnotated(Converter.class, packageNames);
073 Set<Class> classes = resolver.getClasses();
074 for (Class type : classes) {
075 if (LOG.isDebugEnabled()) {
076 LOG.debug("Loading converter class: " + ObjectHelper.name(type));
077 }
078 loadConverterMethods(registry, type);
079 }
080 }
081
082 /**
083 * Finds the names of the packages to search for on the classpath looking
084 * for text files on the classpath at the {@link #META_INF_SERVICES} location.
085 *
086 * @return a collection of packages to search for
087 * @throws IOException is thrown for IO related errors
088 */
089 protected String[] findPackageNames() throws IOException {
090 Set<String> packages = new HashSet<String>();
091 ClassLoader ccl = Thread.currentThread().getContextClassLoader();
092 if (ccl != null) {
093 findPackages(packages, ccl);
094 }
095 findPackages(packages, getClass().getClassLoader());
096 return packages.toArray(new String[packages.size()]);
097 }
098
099 protected void findPackages(Set<String> packages, ClassLoader classLoader) throws IOException {
100 Enumeration<URL> resources = classLoader.getResources(META_INF_SERVICES);
101 while (resources.hasMoreElements()) {
102 URL url = resources.nextElement();
103 if (url != null) {
104 BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream()));
105 try {
106 while (true) {
107 String line = reader.readLine();
108 if (line == null) {
109 break;
110 }
111 line = line.trim();
112 if (line.startsWith("#") || line.length() == 0) {
113 continue;
114 }
115 tokenize(packages, line);
116 }
117 } finally {
118 ObjectHelper.close(reader, null, LOG);
119 }
120 }
121 }
122 }
123
124 /**
125 * Tokenizes the line from the META-IN/services file using commas and
126 * ignoring whitespace between packages
127 */
128 protected void tokenize(Set<String> packages, String line) {
129 StringTokenizer iter = new StringTokenizer(line, ",");
130 while (iter.hasMoreTokens()) {
131 String name = iter.nextToken().trim();
132 if (name.length() > 0) {
133 packages.add(name);
134 }
135 }
136 }
137
138 /**
139 * Loads all of the converter methods for the given type
140 */
141 protected void loadConverterMethods(TypeConverterRegistry registry, Class type) {
142 if (visitedClasses.contains(type)) {
143 return;
144 }
145 visitedClasses.add(type);
146 try {
147 Method[] methods = type.getDeclaredMethods();
148 CachingInjector injector = null;
149
150 for (Method method : methods) {
151 // this may be prone to ClassLoader or packaging problems when the same class is defined
152 // in two different jars (as is the case sometimes with specs).
153 if (ObjectHelper.hasAnnotation(method, Converter.class, true)) {
154 if (isValidConverterMethod(method)) {
155 int modifiers = method.getModifiers();
156 if (isAbstract(modifiers) || !isPublic(modifiers)) {
157 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " + method
158 + " as a converter method is not a public and concrete method");
159 } else {
160 Class<?> toType = method.getReturnType();
161 if (toType.equals(Void.class)) {
162 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: "
163 + method + " as a converter method returns a void method");
164 } else {
165 Class<?> fromType = method.getParameterTypes()[0];
166 if (isStatic(modifiers)) {
167 registerTypeConverter(registry, method, toType, fromType,
168 new StaticMethodTypeConverter(method));
169 } else {
170 if (injector == null) {
171 injector = new CachingInjector(registry, type);
172 }
173 registerTypeConverter(registry, method, toType, fromType,
174 new InstanceMethodTypeConverter(injector, method));
175 }
176 }
177 }
178 } else {
179 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " + method
180 + " as a converter method should have one parameter");
181 }
182 }
183 }
184
185 Class superclass = type.getSuperclass();
186 if (superclass != null && !superclass.equals(Object.class)) {
187 loadConverterMethods(registry, superclass);
188 }
189 } catch (NoClassDefFoundError e) {
190 LOG.warn("Ignoring converter type: " + type.getName() + " as a dependent class could not be found: " + e, e);
191 }
192 }
193
194 protected void registerTypeConverter(TypeConverterRegistry registry,
195 Method method, Class toType, Class fromType, TypeConverter typeConverter) {
196
197 registry.addTypeConverter(toType, fromType, typeConverter);
198 }
199
200 protected boolean isValidConverterMethod(Method method) {
201 Class<?>[] parameterTypes = method.getParameterTypes();
202 return (parameterTypes != null) && (parameterTypes.length == 1
203 || (parameterTypes.length == 2 && Exchange.class.isAssignableFrom(parameterTypes[1])));
204 }
205 }