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; 018 019 020 import java.io.BufferedReader; 021 import java.io.IOException; 022 import java.io.InputStreamReader; 023 024 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.TypeConverter; 037 import org.apache.camel.util.ObjectHelper; 038 import org.apache.camel.util.ResolverUtil; 039 import org.apache.commons.logging.Log; 040 import org.apache.commons.logging.LogFactory; 041 042 043 /** 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: 37863 $ 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 void load(TypeConverterRegistry registry) throws Exception { 056 String[] packageNames = findPackageNames(); 057 resolver.findAnnotated(Converter.class, packageNames); 058 Set<Class> classes = resolver.getClasses(); 059 for (Class type : classes) { 060 if (LOG.isDebugEnabled()) { 061 LOG.debug("Loading converter class: " + ObjectHelper.name(type)); 062 } 063 loadConverterMethods(registry, type); 064 } 065 } 066 067 /** 068 * Finds the names of the packages to search for on the classpath looking 069 * for text files on the classpath at the {@link #META_INF_SERVICES} location. 070 * 071 * @return a collection of packages to search for 072 * @throws IOException is thrown for IO related errors 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 try { 133 Method[] methods = type.getDeclaredMethods(); 134 CachingInjector injector = null; 135 136 for (Method method : methods) { 137 Converter annotation = method.getAnnotation(Converter.class); 138 if (annotation != null) { 139 Class<?>[] parameterTypes = method.getParameterTypes(); 140 if (parameterTypes == null || parameterTypes.length != 1) { 141 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " + method 142 + " as a converter method should have one parameter"); 143 } else { 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 = parameterTypes[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 } 168 } 169 } 170 Class superclass = type.getSuperclass(); 171 if (superclass != null && !superclass.equals(Object.class)) { 172 loadConverterMethods(registry, superclass); 173 } 174 } catch (NoClassDefFoundError e) { 175 LOG.debug("Ignoring converter type: " + type.getName() + " as a dependent class could not be found: " + e, e); 176 } 177 } 178 179 protected void registerTypeConverter(TypeConverterRegistry registry, Method method, 180 Class toType, Class fromType, TypeConverter typeConverter) { 181 182 registry.addTypeConverter(toType, fromType, typeConverter); 183 } 184 }