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 import java.lang.reflect.Method;
023 import java.net.URL;
024 import java.util.Enumeration;
025 import java.util.HashSet;
026 import java.util.Set;
027 import java.util.StringTokenizer;
028
029 import static java.lang.reflect.Modifier.isAbstract;
030 import static java.lang.reflect.Modifier.isPublic;
031 import static java.lang.reflect.Modifier.isStatic;
032
033 import org.apache.camel.Converter;
034 import org.apache.camel.impl.CachingInjector;
035 import org.apache.camel.util.ObjectHelper;
036 import org.apache.camel.util.ResolverUtil;
037 import org.apache.commons.logging.Log;
038 import org.apache.commons.logging.LogFactory;
039
040
041 /**
042 * A class which will auto-discover converter objects and methods to pre-load
043 * the registry of converters on startup
044 *
045 * @version $Revision: 563607 $
046 */
047 public class AnnotationTypeConverterLoader implements TypeConverterLoader {
048 public static final String META_INF_SERVICES = "META-INF/services/org/apache/camel/TypeConverter";
049 private static final transient Log LOG = LogFactory.getLog(AnnotationTypeConverterLoader.class);
050 private ResolverUtil resolver = new ResolverUtil();
051 private Set<Class> visitedClasses = new HashSet<Class>();
052
053 public void load(TypeConverterRegistry registry) throws Exception {
054 String[] packageNames = findPackageNames();
055 resolver.findAnnotated(Converter.class, packageNames);
056 Set<Class> classes = resolver.getClasses();
057 for (Class type : classes) {
058 if (LOG.isDebugEnabled()) {
059 LOG.debug("Loading converter class: " + ObjectHelper.name(type));
060 }
061 loadConverterMethods(registry, type);
062 }
063 }
064
065 /**
066 * Finds the names of the packages to search for on the classpath looking
067 * for text files on the classpath at the
068 *
069 * @{link #META_INF_SERVICES} location
070 *
071 * @return a collection of packages to search for
072 * @throws IOException
073 */
074 protected String[] findPackageNames() throws IOException {
075 Set<String> packages = new HashSet<String>();
076 findPackages(packages, Thread.currentThread().getContextClassLoader());
077 findPackages(packages, getClass().getClassLoader());
078 return packages.toArray(new String[packages.size()]);
079 }
080
081 protected void findPackages(Set<String> packages, ClassLoader classLoader) throws IOException {
082 Enumeration<URL> resources = classLoader.getResources(META_INF_SERVICES);
083 while (resources.hasMoreElements()) {
084 URL url = resources.nextElement();
085 if (url != null) {
086 BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream()));
087 try {
088 while (true) {
089 String line = reader.readLine();
090 if (line == null) {
091 break;
092 }
093 line = line.trim();
094 if (line.startsWith("#") || line.length() == 0) {
095 continue;
096 }
097 tokenize(packages, line);
098 }
099 } finally {
100 try {
101 reader.close();
102 } catch (IOException e) {
103 LOG.warn("Caught exception closing stream: " + e, e);
104 }
105 }
106 }
107 }
108 }
109
110 /**
111 * Tokenizes the line from the META-IN/services file using commas and
112 * ignoring whitespace between packages
113 */
114 protected void tokenize(Set<String> packages, String line) {
115 StringTokenizer iter = new StringTokenizer(line, ",");
116 while (iter.hasMoreTokens()) {
117 String name = iter.nextToken().trim();
118 if (name.length() > 0) {
119 packages.add(name);
120 }
121 }
122 }
123
124 /**
125 * Loads all of the converter methods for the given type
126 */
127 protected void loadConverterMethods(TypeConverterRegistry registry, Class type) {
128 if (visitedClasses.contains(type)) {
129 return;
130 }
131 visitedClasses.add(type);
132 Method[] methods = type.getDeclaredMethods();
133 CachingInjector injector = null;
134
135 for (Method method : methods) {
136 Converter annotation = method.getAnnotation(Converter.class);
137 if (annotation != null) {
138 Class<?>[] parameterTypes = method.getParameterTypes();
139 if (parameterTypes == null || parameterTypes.length != 1) {
140 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " + method
141 + " as a converter method should have one parameter");
142 } else {
143 int modifiers = method.getModifiers();
144 if (isAbstract(modifiers) || !isPublic(modifiers)) {
145 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " + method
146 + " as a converter method is not a public and concrete method");
147 } else {
148 Class toType = method.getReturnType();
149 if (toType.equals(Void.class)) {
150 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: "
151 + method + " as a converter method returns a void method");
152 } else {
153 Class fromType = parameterTypes[0];
154 if (isStatic(modifiers)) {
155 registry.addTypeConverter(toType, fromType,
156 new StaticMethodTypeConverter(method));
157 } else {
158 if (injector == null) {
159 injector = new CachingInjector(registry, type);
160 }
161 registry.addTypeConverter(toType, fromType,
162 new InstanceMethodTypeConverter(injector, method));
163 }
164 }
165 }
166 }
167 }
168 }
169 Class superclass = type.getSuperclass();
170 if (superclass != null && !superclass.equals(Object.class)) {
171 loadConverterMethods(registry, superclass);
172 }
173 }
174 }