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.impl.CachingInjector; 038 import org.apache.camel.util.ObjectHelper; 039 import org.apache.camel.util.ResolverUtil; 040 import org.apache.commons.logging.Log; 041 import org.apache.commons.logging.LogFactory; 042 043 044 /** 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: 642753 $ 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 = new ResolverUtil(); 054 private Set<Class> visitedClasses = new HashSet<Class>(); 055 056 public void load(TypeConverterRegistry registry) throws Exception { 057 String[] packageNames = findPackageNames(); 058 resolver.findAnnotated(Converter.class, packageNames); 059 Set<Class> classes = resolver.getClasses(); 060 for (Class type : classes) { 061 if (LOG.isDebugEnabled()) { 062 LOG.debug("Loading converter class: " + ObjectHelper.name(type)); 063 } 064 loadConverterMethods(registry, type); 065 } 066 } 067 068 /** 069 * Finds the names of the packages to search for on the classpath looking 070 * for text files on the classpath at the {@link #META_INF_SERVICES} location. 071 * 072 * @return a collection of packages to search for 073 * @throws IOException is thrown for IO relatede errors 074 */ 075 protected String[] findPackageNames() throws IOException { 076 Set<String> packages = new HashSet<String>(); 077 findPackages(packages, Thread.currentThread().getContextClassLoader()); 078 findPackages(packages, getClass().getClassLoader()); 079 return packages.toArray(new String[packages.size()]); 080 } 081 082 protected void findPackages(Set<String> packages, ClassLoader classLoader) throws IOException { 083 Enumeration<URL> resources = classLoader.getResources(META_INF_SERVICES); 084 while (resources.hasMoreElements()) { 085 URL url = resources.nextElement(); 086 if (url != null) { 087 BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream())); 088 try { 089 while (true) { 090 String line = reader.readLine(); 091 if (line == null) { 092 break; 093 } 094 line = line.trim(); 095 if (line.startsWith("#") || line.length() == 0) { 096 continue; 097 } 098 tokenize(packages, line); 099 } 100 } finally { 101 try { 102 reader.close(); 103 } catch (IOException e) { 104 LOG.warn("Caught exception closing stream: " + e, e); 105 } 106 } 107 } 108 } 109 } 110 111 /** 112 * Tokenizes the line from the META-IN/services file using commas and 113 * ignoring whitespace between packages 114 */ 115 protected void tokenize(Set<String> packages, String line) { 116 StringTokenizer iter = new StringTokenizer(line, ","); 117 while (iter.hasMoreTokens()) { 118 String name = iter.nextToken().trim(); 119 if (name.length() > 0) { 120 packages.add(name); 121 } 122 } 123 } 124 125 /** 126 * Loads all of the converter methods for the given type 127 */ 128 protected void loadConverterMethods(TypeConverterRegistry registry, Class type) { 129 if (visitedClasses.contains(type)) { 130 return; 131 } 132 visitedClasses.add(type); 133 try { 134 Method[] methods = type.getDeclaredMethods(); 135 CachingInjector injector = null; 136 137 for (Method method : methods) { 138 Converter annotation = method.getAnnotation(Converter.class); 139 if (annotation != null) { 140 Class<?>[] parameterTypes = method.getParameterTypes(); 141 if (parameterTypes == null || parameterTypes.length != 1) { 142 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " + method 143 + " as a converter method should have one parameter"); 144 } else { 145 int modifiers = method.getModifiers(); 146 if (isAbstract(modifiers) || !isPublic(modifiers)) { 147 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " + method 148 + " as a converter method is not a public and concrete method"); 149 } else { 150 Class toType = method.getReturnType(); 151 if (toType.equals(Void.class)) { 152 LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " 153 + method + " as a converter method returns a void method"); 154 } else { 155 Class fromType = parameterTypes[0]; 156 if (isStatic(modifiers)) { 157 registerTypeConverter(registry, method, toType, fromType, 158 new StaticMethodTypeConverter(method)); 159 } else { 160 if (injector == null) { 161 injector = new CachingInjector(registry, type); 162 } 163 registerTypeConverter(registry, method, toType, fromType, 164 new InstanceMethodTypeConverter(injector, method)); 165 } 166 } 167 } 168 } 169 } 170 } 171 Class superclass = type.getSuperclass(); 172 if (superclass != null && !superclass.equals(Object.class)) { 173 loadConverterMethods(registry, superclass); 174 } 175 } catch (NoClassDefFoundError e) { 176 LOG.debug("Ignoring converter type: " + type.getName() + " as a dependent class could not be found: " + e, e); 177 } 178 } 179 180 protected void registerTypeConverter(TypeConverterRegistry registry, Method method, 181 Class toType, Class fromType, TypeConverter typeConverter) { 182 183 registry.addTypeConverter(toType, fromType, typeConverter); 184 } 185 }