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: 65385 $
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 findPackages(packages, Thread.currentThread().getContextClassLoader());
092 findPackages(packages, getClass().getClassLoader());
093 return packages.toArray(new String[packages.size()]);
094 }
095
096 protected void findPackages(Set<String> packages, ClassLoader classLoader) throws IOException {
097 Enumeration<URL> resources = classLoader.getResources(META_INF_SERVICES);
098 while (resources.hasMoreElements()) {
099 URL url = resources.nextElement();
100 if (url != null) {
101 BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream()));
102 try {
103 while (true) {
104 String line = reader.readLine();
105 if (line == null) {
106 break;
107 }
108 line = line.trim();
109 if (line.startsWith("#") || line.length() == 0) {
110 continue;
111 }
112 tokenize(packages, line);
113 }
114 } finally {
115 ObjectHelper.close(reader, null, LOG);
116 }
117 }
118 }
119 }
120
121 /**
122 * Tokenizes the line from the META-IN/services file using commas and
123 * ignoring whitespace between packages
124 */
125 protected void tokenize(Set<String> packages, String line) {
126 StringTokenizer iter = new StringTokenizer(line, ",");
127 while (iter.hasMoreTokens()) {
128 String name = iter.nextToken().trim();
129 if (name.length() > 0) {
130 packages.add(name);
131 }
132 }
133 }
134
135 /**
136 * Loads all of the converter methods for the given type
137 */
138 protected void loadConverterMethods(TypeConverterRegistry registry, Class type) {
139 if (visitedClasses.contains(type)) {
140 return;
141 }
142 visitedClasses.add(type);
143 try {
144 Method[] methods = type.getDeclaredMethods();
145 CachingInjector injector = null;
146
147 for (Method method : methods) {
148 // this may be prone to ClassLoader or packaging problems when the same class is defined
149 // in two different jars (as is the case sometimes with specs).
150 if (ObjectHelper.hasAnnotation(method, Converter.class, true)) {
151 if (isValidConverterMethod(method)) {
152 int modifiers = method.getModifiers();
153 if (isAbstract(modifiers) || !isPublic(modifiers)) {
154 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " + method
155 + " as a converter method is not a public and concrete method");
156 } else {
157 Class<?> toType = method.getReturnType();
158 if (toType.equals(Void.class)) {
159 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: "
160 + method + " as a converter method returns a void method");
161 } else {
162 Class<?> fromType = method.getParameterTypes()[0];
163 if (isStatic(modifiers)) {
164 registerTypeConverter(registry, method, toType, fromType,
165 new StaticMethodTypeConverter(method));
166 } else {
167 if (injector == null) {
168 injector = new CachingInjector(registry, type);
169 }
170 registerTypeConverter(registry, method, toType, fromType,
171 new InstanceMethodTypeConverter(injector, method));
172 }
173 }
174 }
175 } else {
176 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " + method
177 + " as a converter method should have one parameter");
178 }
179 }
180 }
181
182 Class superclass = type.getSuperclass();
183 if (superclass != null && !superclass.equals(Object.class)) {
184 loadConverterMethods(registry, superclass);
185 }
186 } catch (NoClassDefFoundError e) {
187 LOG.warn("Ignoring converter type: " + type.getName() + " as a dependent class could not be found: " + e, e);
188 }
189 }
190
191 protected void registerTypeConverter(TypeConverterRegistry registry,
192 Method method, Class toType, Class fromType, TypeConverter typeConverter) {
193
194 registry.addTypeConverter(toType, fromType, typeConverter);
195 }
196
197 protected boolean isValidConverterMethod(Method method) {
198 Class<?>[] parameterTypes = method.getParameterTypes();
199 return (parameterTypes != null) && (parameterTypes.length == 1
200 || (parameterTypes.length == 2 && Exchange.class.isAssignableFrom(parameterTypes[1])));
201 }
202 }