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.reflect.Method; 024 025 import java.net.URL; 026 import java.util.Enumeration; 027 import java.util.HashSet; 028 import java.util.Set; 029 import java.util.StringTokenizer; 030 import static java.lang.reflect.Modifier.isAbstract; 031 import static java.lang.reflect.Modifier.isPublic; 032 import static java.lang.reflect.Modifier.isStatic; 033 034 import org.apache.camel.Converter; 035 import org.apache.camel.Exchange; 036 import org.apache.camel.TypeConverter; 037 import org.apache.camel.util.ObjectHelper; 038 import org.apache.camel.util.ResolverUtil; 039 import org.apache.camel.util.WebSphereResolverUtil; 040 import org.apache.commons.logging.Log; 041 import org.apache.commons.logging.LogFactory; 042 043 /** 044 * A class which will auto-discover converter objects and methods to pre-load 045 * the registry of converters on startup 046 * 047 * @version $Revision: 47146 $ 048 */ 049 public class AnnotationTypeConverterLoader implements TypeConverterLoader { 050 public static final String META_INF_SERVICES = "META-INF/services/org/apache/camel/TypeConverter"; 051 private static final transient Log LOG = LogFactory.getLog(AnnotationTypeConverterLoader.class); 052 private ResolverUtil resolver = new ResolverUtil(); 053 private Set<Class> visitedClasses = new HashSet<Class>(); 054 055 public AnnotationTypeConverterLoader() { 056 // use WebSphere specific resolver if running on WebSphere 057 if (WebSphereResolverUtil.isWebSphereClassLoader(this.getClass().getClassLoader())) { 058 LOG.info("Using WebSphere specific ResolverUtil"); 059 resolver = new WebSphereResolverUtil(META_INF_SERVICES); 060 } 061 } 062 063 public void load(TypeConverterRegistry registry) throws Exception { 064 String[] packageNames = findPackageNames(); 065 resolver.findAnnotated(Converter.class, packageNames); 066 Set<Class> classes = resolver.getClasses(); 067 for (Class type : classes) { 068 if (LOG.isDebugEnabled()) { 069 LOG.debug("Loading converter class: " + ObjectHelper.name(type)); 070 } 071 loadConverterMethods(registry, type); 072 } 073 } 074 075 /** 076 * Finds the names of the packages to search for on the classpath looking 077 * for text files on the classpath at the {@link #META_INF_SERVICES} location. 078 * 079 * @return a collection of packages to search for 080 * @throws IOException is thrown for IO related errors 081 */ 082 protected String[] findPackageNames() throws IOException { 083 Set<String> packages = new HashSet<String>(); 084 findPackages(packages, Thread.currentThread().getContextClassLoader()); 085 findPackages(packages, getClass().getClassLoader()); 086 return packages.toArray(new String[packages.size()]); 087 } 088 089 protected void findPackages(Set<String> packages, ClassLoader classLoader) throws IOException { 090 Enumeration<URL> resources = classLoader.getResources(META_INF_SERVICES); 091 while (resources.hasMoreElements()) { 092 URL url = resources.nextElement(); 093 if (url != null) { 094 BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream())); 095 try { 096 while (true) { 097 String line = reader.readLine(); 098 if (line == null) { 099 break; 100 } 101 line = line.trim(); 102 if (line.startsWith("#") || line.length() == 0) { 103 continue; 104 } 105 tokenize(packages, line); 106 } 107 } finally { 108 ObjectHelper.close(reader, null, LOG); 109 } 110 } 111 } 112 } 113 114 /** 115 * Tokenizes the line from the META-IN/services file using commas and 116 * ignoring whitespace between packages 117 */ 118 protected void tokenize(Set<String> packages, String line) { 119 StringTokenizer iter = new StringTokenizer(line, ","); 120 while (iter.hasMoreTokens()) { 121 String name = iter.nextToken().trim(); 122 if (name.length() > 0) { 123 packages.add(name); 124 } 125 } 126 } 127 128 /** 129 * Loads all of the converter methods for the given type 130 */ 131 protected void loadConverterMethods(TypeConverterRegistry registry, Class type) { 132 if (visitedClasses.contains(type)) { 133 return; 134 } 135 visitedClasses.add(type); 136 try { 137 Method[] methods = type.getDeclaredMethods(); 138 CachingInjector injector = null; 139 140 for (Method method : methods) { 141 Converter annotation = method.getAnnotation(Converter.class); 142 if (annotation != null) { 143 if (isValidConverterMethod(method)) { 144 int modifiers = method.getModifiers(); 145 if (isAbstract(modifiers) || !isPublic(modifiers)) { 146 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " + method 147 + " as a converter method is not a public and concrete method"); 148 } else { 149 Class<?> toType = method.getReturnType(); 150 if (toType.equals(Void.class)) { 151 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " 152 + method + " as a converter method returns a void method"); 153 } else { 154 Class<?> fromType = method.getParameterTypes()[0]; 155 if (isStatic(modifiers)) { 156 registerTypeConverter(registry, method, toType, fromType, 157 new StaticMethodTypeConverter(method)); 158 } else { 159 if (injector == null) { 160 injector = new CachingInjector(registry, type); 161 } 162 registerTypeConverter(registry, method, toType, fromType, 163 new InstanceMethodTypeConverter(injector, method)); 164 } 165 } 166 } 167 } else { 168 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " + method 169 + " as a converter method should have one parameter"); 170 } 171 } 172 } 173 174 Class superclass = type.getSuperclass(); 175 if (superclass != null && !superclass.equals(Object.class)) { 176 loadConverterMethods(registry, superclass); 177 } 178 } catch (NoClassDefFoundError e) { 179 LOG.debug("Ignoring converter type: " + type.getName() + " as a dependent class could not be found: " + e, e); 180 } 181 } 182 183 protected void registerTypeConverter(TypeConverterRegistry registry, 184 Method method, Class toType, Class fromType, TypeConverter typeConverter) { 185 186 registry.addTypeConverter(toType, fromType, typeConverter); 187 } 188 189 protected boolean isValidConverterMethod(Method method) { 190 Class<?>[] parameterTypes = method.getParameterTypes(); 191 return (parameterTypes != null) && (parameterTypes.length == 1 192 || (parameterTypes.length == 2 && Exchange.class.isAssignableFrom(parameterTypes[1]))); 193 } 194 }