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.IOException;
020 import java.util.ArrayList;
021 import java.util.List;
022 import java.util.Map;
023 import java.util.Set;
024 import java.util.concurrent.ConcurrentHashMap;
025
026 import org.apache.camel.Exchange;
027 import org.apache.camel.RuntimeCamelException;
028 import org.apache.camel.TypeConverter;
029 import org.apache.camel.spi.Injector;
030 import org.apache.camel.spi.TypeConverterAware;
031 import org.apache.camel.util.FactoryFinder;
032 import org.apache.camel.util.NoFactoryAvailableException;
033 import org.apache.camel.util.ObjectHelper;
034 import org.apache.commons.logging.Log;
035 import org.apache.commons.logging.LogFactory;
036
037 /**
038 * Default implementation of a type converter registry used for
039 * <a href="http://activemq.apache.org/camel/type-converter.html">type converters</a> in Camel.
040 *
041 * @version $Revision: 46981 $
042 */
043 public class DefaultTypeConverter implements TypeConverter, TypeConverterRegistry {
044 private static final transient Log LOG = LogFactory.getLog(DefaultTypeConverter.class);
045 private final Map<TypeMapping, TypeConverter> typeMappings = new ConcurrentHashMap<TypeMapping, TypeConverter>();
046 private Injector injector;
047 private List<TypeConverterLoader> typeConverterLoaders = new ArrayList<TypeConverterLoader>();
048 private List<TypeConverter> fallbackConverters = new ArrayList<TypeConverter>();
049 private boolean loaded;
050
051 public DefaultTypeConverter(Injector injector) {
052 typeConverterLoaders.add(new AnnotationTypeConverterLoader());
053 this.injector = injector;
054 addFallbackConverter(new AsyncProcessorTypeConverter());
055 addFallbackConverter(new PropertyEditorTypeConverter());
056 addFallbackConverter(new ToStringTypeConverter());
057 addFallbackConverter(new ArrayTypeConverter());
058 addFallbackConverter(new EnumTypeConverter());
059 }
060
061 public <T> T convertTo(Class<T> type, Object value) {
062 return convertTo(type, null, value);
063 }
064
065 @SuppressWarnings("unchecked")
066 public <T> T convertTo(Class<T> type, Exchange exchange, Object value) {
067 if (type.isInstance(value)) {
068 return type.cast(value);
069 }
070 checkLoaded();
071 TypeConverter converter = getOrFindTypeConverter(type, value);
072 if (converter != null) {
073 return converter.convertTo(type, exchange, value);
074 }
075
076 for (TypeConverter fallback : fallbackConverters) {
077 T rc = fallback.convertTo(type, exchange, value);
078 if (rc != null) {
079 return rc;
080 }
081 }
082
083 // lets avoid NullPointerException when converting to boolean for null values
084 if (boolean.class.isAssignableFrom(type)) {
085 return (T) Boolean.FALSE;
086 }
087 if (type.isPrimitive()) {
088 Class primitiveType = ObjectHelper.convertPrimitiveTypeToWrapperType(type);
089 if (primitiveType != type) {
090 return (T) convertTo(primitiveType, exchange, value);
091 }
092 }
093 return null;
094 }
095
096 public void addTypeConverter(Class toType, Class fromType, TypeConverter typeConverter) {
097 TypeMapping key = new TypeMapping(toType, fromType);
098 synchronized (typeMappings) {
099 TypeConverter converter = typeMappings.get(key);
100 if (converter != null) {
101 LOG.warn("Overriding type converter from: " + converter + " to: " + typeConverter);
102 }
103 typeMappings.put(key, typeConverter);
104 }
105 }
106
107 public void addFallbackConverter(TypeConverter converter) {
108 fallbackConverters.add(converter);
109 if (converter instanceof TypeConverterAware) {
110 TypeConverterAware typeConverterAware = (TypeConverterAware)converter;
111 typeConverterAware.setTypeConverter(this);
112 }
113 }
114
115 public TypeConverter getTypeConverter(Class toType, Class fromType) {
116 TypeMapping key = new TypeMapping(toType, fromType);
117 return typeMappings.get(key);
118 }
119
120 public Injector getInjector() {
121 return injector;
122 }
123
124 public void setInjector(Injector injector) {
125 this.injector = injector;
126 }
127
128 protected <T> TypeConverter getOrFindTypeConverter(Class toType, Object value) {
129 Class fromType = null;
130 if (value != null) {
131 fromType = value.getClass();
132 }
133 TypeMapping key = new TypeMapping(toType, fromType);
134 TypeConverter converter;
135 synchronized (typeMappings) {
136 converter = typeMappings.get(key);
137 if (converter == null) {
138 converter = findTypeConverter(toType, fromType, value);
139 if (converter != null) {
140 typeMappings.put(key, converter);
141 }
142 }
143 }
144 return converter;
145 }
146
147 /**
148 * Tries to auto-discover any available type converters
149 */
150 protected TypeConverter findTypeConverter(Class toType, Class fromType, Object value) {
151 // lets try the super classes of the from type
152 if (fromType != null) {
153 Class fromSuperClass = fromType.getSuperclass();
154 if (fromSuperClass != null && !fromSuperClass.equals(Object.class)) {
155
156 TypeConverter converter = getTypeConverter(toType, fromSuperClass);
157 if (converter == null) {
158 converter = findTypeConverter(toType, fromSuperClass, value);
159 }
160 if (converter != null) {
161 return converter;
162 }
163 }
164 for (Class type : fromType.getInterfaces()) {
165 TypeConverter converter = getTypeConverter(toType, type);
166 if (converter != null) {
167 return converter;
168 }
169 }
170
171 // lets test for arrays
172 if (fromType.isArray() && !fromType.getComponentType().isPrimitive()) {
173 // TODO can we try walking the inheritance-tree for the element types?
174 if (!fromType.equals(Object[].class)) {
175 fromSuperClass = Object[].class;
176
177 TypeConverter converter = getTypeConverter(toType, fromSuperClass);
178 if (converter == null) {
179 converter = findTypeConverter(toType, fromSuperClass, value);
180 }
181 if (converter != null) {
182 return converter;
183 }
184 }
185 }
186
187 // lets test for Object based converters
188 if (!fromType.equals(Object.class)) {
189 TypeConverter converter = getTypeConverter(toType, Object.class);
190 if (converter != null) {
191 return converter;
192 }
193 }
194 }
195
196 // lets try classes derived from this toType
197 if (fromType != null) {
198 Set<Map.Entry<TypeMapping, TypeConverter>> entries = typeMappings.entrySet();
199 for (Map.Entry<TypeMapping, TypeConverter> entry : entries) {
200 TypeMapping key = entry.getKey();
201 Class aToType = key.getToType();
202 if (toType.isAssignableFrom(aToType)) {
203 if (key.getFromType().isAssignableFrom(fromType)) {
204 return entry.getValue();
205 }
206 }
207 }
208 }
209
210 // TODO look at constructors of toType?
211 return null;
212 }
213
214 /**
215 * Checks if the registry is loaded and if not lazily load it
216 */
217 protected synchronized void checkLoaded() {
218 if (!loaded) {
219 loaded = true;
220 try {
221 for (TypeConverterLoader typeConverterLoader : typeConverterLoaders) {
222 typeConverterLoader.load(this);
223 }
224
225 // lets try load any other fallback converters
226 try {
227 loadFallbackTypeConverters();
228 } catch (NoFactoryAvailableException e) {
229 // ignore its fine to have none
230 }
231 } catch (Exception e) {
232 throw new RuntimeCamelException(e);
233 }
234 }
235 }
236
237 protected void loadFallbackTypeConverters() throws IOException, ClassNotFoundException {
238 FactoryFinder finder = new FactoryFinder();
239 List<TypeConverter> converters = finder.newInstances("FallbackTypeConverter", getInjector(),
240 TypeConverter.class);
241 for (TypeConverter converter : converters) {
242 addFallbackConverter(converter);
243 }
244 }
245
246 /**
247 * Represents a mapping from one type (which can be null) to another
248 */
249 protected static class TypeMapping {
250 Class toType;
251 Class fromType;
252
253 public TypeMapping(Class toType, Class fromType) {
254 this.toType = toType;
255 this.fromType = fromType;
256 }
257
258 public Class getFromType() {
259 return fromType;
260 }
261
262 public Class getToType() {
263 return toType;
264 }
265
266 @Override
267 public boolean equals(Object object) {
268 if (object instanceof TypeMapping) {
269 TypeMapping that = (TypeMapping)object;
270 return ObjectHelper.equal(this.fromType, that.fromType)
271 && ObjectHelper.equal(this.toType, that.toType);
272 }
273 return false;
274 }
275
276 @Override
277 public int hashCode() {
278 int answer = toType.hashCode();
279 if (fromType != null) {
280 answer *= 37 + fromType.hashCode();
281 }
282 return answer;
283 }
284
285 @Override
286 public String toString() {
287 return "[" + fromType + "=>" + toType + "]";
288 }
289 }
290 }