Source Code Cross Referenced for TurbineFactoryService.java in  » Web-Framework » TURBINE » org » apache » turbine » services » factory » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Web Framework » TURBINE » org.apache.turbine.services.factory 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        package org.apache.turbine.services.factory;
002:
003:        /*
004:         * Licensed to the Apache Software Foundation (ASF) under one
005:         * or more contributor license agreements.  See the NOTICE file
006:         * distributed with this work for additional information
007:         * regarding copyright ownership.  The ASF licenses this file
008:         * to you under the Apache License, Version 2.0 (the
009:         * "License"); you may not use this file except in compliance
010:         * with the License.  You may obtain a copy of the License at
011:         *
012:         *   http://www.apache.org/licenses/LICENSE-2.0
013:         *
014:         * Unless required by applicable law or agreed to in writing,
015:         * software distributed under the License is distributed on an
016:         * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017:         * KIND, either express or implied.  See the License for the
018:         * specific language governing permissions and limitations
019:         * under the License.
020:         */
021:
022:        import java.io.ByteArrayInputStream;
023:        import java.io.ByteArrayOutputStream;
024:        import java.io.ObjectOutputStream;
025:        import java.util.ArrayList;
026:        import java.util.HashMap;
027:        import java.util.Iterator;
028:        import java.util.List;
029:
030:        import org.apache.commons.configuration.Configuration;
031:
032:        import org.apache.turbine.services.InitializationException;
033:        import org.apache.turbine.services.TurbineBaseService;
034:        import org.apache.turbine.util.TurbineException;
035:        import org.apache.turbine.util.pool.ObjectInputStreamForContext;
036:
037:        /**
038:         * The Factory Service instantiates objects using specified
039:         * class loaders. If none is specified, the default one
040:         * will be used.
041:         *
042:         * @author <a href="mailto:ilkka.priha@simsoft.fi">Ilkka Priha</a>
043:         * @version $Id: TurbineFactoryService.java 534527 2007-05-02 16:10:59Z tv $
044:         */
045:        public class TurbineFactoryService extends TurbineBaseService implements 
046:                FactoryService {
047:            /**
048:             * The property specifying a set of additional class loaders.
049:             */
050:            public static final String CLASS_LOADERS = "class.loaders";
051:
052:            /**
053:             * The property prefix specifying additional object factories.
054:             */
055:            public static final String OBJECT_FACTORY = "factory.";
056:
057:            /**
058:             * Primitive classes for reflection of constructors.
059:             */
060:            private static HashMap primitiveClasses;
061:
062:            {
063:                primitiveClasses = new HashMap(8);
064:                primitiveClasses.put(Boolean.TYPE.toString(), Boolean.TYPE);
065:                primitiveClasses.put(Character.TYPE.toString(), Character.TYPE);
066:                primitiveClasses.put(Byte.TYPE.toString(), Byte.TYPE);
067:                primitiveClasses.put(Short.TYPE.toString(), Short.TYPE);
068:                primitiveClasses.put(Integer.TYPE.toString(), Integer.TYPE);
069:                primitiveClasses.put(Long.TYPE.toString(), Long.TYPE);
070:                primitiveClasses.put(Float.TYPE.toString(), Float.TYPE);
071:                primitiveClasses.put(Double.TYPE.toString(), Double.TYPE);
072:            }
073:
074:            /**
075:             * Additional class loaders.
076:             */
077:            private ArrayList classLoaders = new ArrayList();
078:
079:            /**
080:             * Customized object factories.
081:             */
082:            private HashMap objectFactories = new HashMap();
083:
084:            /**
085:             * Gets the class of a primitive type.
086:             *
087:             * @param type a primitive type.
088:             * @return the corresponding class, or null.
089:             */
090:            protected static Class getPrimitiveClass(String type) {
091:                return (Class) primitiveClasses.get(type);
092:            }
093:
094:            /**
095:             * Constructs a Factory Service.
096:             */
097:            public TurbineFactoryService() {
098:            }
099:
100:            /**
101:             * Initializes the service by loading default class loaders
102:             * and customized object factories.
103:             *
104:             * @throws InitializationException if initialization fails.
105:             */
106:            public void init() throws InitializationException {
107:                Configuration conf = getConfiguration();
108:                if (conf != null) {
109:                    List loaders = conf.getList(CLASS_LOADERS);
110:                    if (loaders != null) {
111:                        for (int i = 0; i < loaders.size(); i++) {
112:                            try {
113:                                classLoaders.add(loadClass(
114:                                        (String) loaders.get(i)).newInstance());
115:                            } catch (Exception x) {
116:                                throw new InitializationException(
117:                                        "No such class loader '"
118:                                                + (String) loaders.get(i)
119:                                                + "' for TurbineFactoryService",
120:                                        x);
121:                            }
122:                        }
123:                    }
124:
125:                    String key, factory;
126:                    for (Iterator i = conf.getKeys(OBJECT_FACTORY); i.hasNext();) {
127:                        key = (String) i.next();
128:                        factory = conf.getString(key);
129:
130:                        /*
131:                         * Store the factory to the table as a string and
132:                         * instantiate it by using the service when needed.
133:                         */
134:                        objectFactories.put(key.substring(OBJECT_FACTORY
135:                                .length()), factory);
136:                    }
137:                }
138:                setInit(true);
139:            }
140:
141:            /**
142:             * Gets an instance of a named class.
143:             *
144:             * @param className the name of the class.
145:             * @return the instance.
146:             * @throws TurbineException if instantiation fails.
147:             */
148:            public Object getInstance(String className) throws TurbineException {
149:                if (className == null) {
150:                    throw new TurbineException(new NullPointerException(
151:                            "String className"));
152:                }
153:
154:                Factory factory = getFactory(className);
155:                if (factory == null) {
156:                    Class clazz;
157:                    try {
158:                        clazz = loadClass(className);
159:                    } catch (ClassNotFoundException x) {
160:                        throw new TurbineException(
161:                                "Instantiation failed for class " + className,
162:                                x);
163:                    }
164:                    return getInstance(clazz);
165:                } else {
166:                    return factory.getInstance();
167:                }
168:            }
169:
170:            /**
171:             * Gets an instance of a named class using a specified class loader.
172:             *
173:             * <p>Class loaders are supported only if the isLoaderSupported
174:             * method returns true. Otherwise the loader parameter is ignored.
175:             *
176:             * @param className the name of the class.
177:             * @param loader the class loader.
178:             * @return the instance.
179:             * @throws TurbineException if instantiation fails.
180:             */
181:            public Object getInstance(String className, ClassLoader loader)
182:                    throws TurbineException {
183:                if (className == null) {
184:                    throw new TurbineException(new NullPointerException(
185:                            "String className"));
186:                }
187:
188:                Factory factory = getFactory(className);
189:                if (factory == null) {
190:                    if (loader != null) {
191:                        Class clazz;
192:                        try {
193:                            clazz = loadClass(className, loader);
194:                        } catch (ClassNotFoundException x) {
195:                            throw new TurbineException(
196:                                    "Instantiation failed for class "
197:                                            + className, x);
198:                        }
199:                        return getInstance(clazz);
200:                    } else {
201:                        return getInstance(className);
202:                    }
203:                } else {
204:                    return factory.getInstance(loader);
205:                }
206:            }
207:
208:            /**
209:             * Gets an instance of a named class.
210:             * Parameters for its constructor are given as an array of objects,
211:             * primitive types must be wrapped with a corresponding class.
212:             *
213:             * @param className the name of the class.
214:             * @param params an array containing the parameters of the constructor.
215:             * @param signature an array containing the signature of the constructor.
216:             * @return the instance.
217:             * @throws TurbineException if instantiation fails.
218:             */
219:            public Object getInstance(String className, Object[] params,
220:                    String[] signature) throws TurbineException {
221:                if (className == null) {
222:                    throw new TurbineException(new NullPointerException(
223:                            "String className"));
224:                }
225:
226:                Factory factory = getFactory(className);
227:                if (factory == null) {
228:                    Class clazz;
229:                    try {
230:                        clazz = loadClass(className);
231:                    } catch (ClassNotFoundException x) {
232:                        throw new TurbineException(
233:                                "Instantiation failed for class " + className,
234:                                x);
235:                    }
236:                    return getInstance(clazz, params, signature);
237:                } else {
238:                    return factory.getInstance(params, signature);
239:                }
240:            }
241:
242:            /**
243:             * Gets an instance of a named class using a specified class loader.
244:             * Parameters for its constructor are given as an array of objects,
245:             * primitive types must be wrapped with a corresponding class.
246:             *
247:             * <p>Class loaders are supported only if the isLoaderSupported
248:             * method returns true. Otherwise the loader parameter is ignored.
249:             *
250:             * @param className the name of the class.
251:             * @param loader the class loader.
252:             * @param params an array containing the parameters of the constructor.
253:             * @param signature an array containing the signature of the constructor.
254:             * @return the instance.
255:             * @throws TurbineException if instantiation fails.
256:             */
257:            public Object getInstance(String className, ClassLoader loader,
258:                    Object[] params, String[] signature)
259:                    throws TurbineException {
260:                if (className == null) {
261:                    throw new TurbineException(new NullPointerException(
262:                            "String className"));
263:                }
264:
265:                Factory factory = getFactory(className);
266:                if (factory == null) {
267:                    if (loader != null) {
268:                        Class clazz;
269:                        try {
270:                            clazz = loadClass(className, loader);
271:                        } catch (ClassNotFoundException x) {
272:                            throw new TurbineException(
273:                                    "Instantiation failed for class "
274:                                            + className, x);
275:                        }
276:                        return getInstance(clazz, params, signature);
277:                    } else {
278:                        return getInstance(className, params, signature);
279:                    }
280:                } else {
281:                    return factory.getInstance(loader, params, signature);
282:                }
283:            }
284:
285:            /**
286:             * Tests if specified class loaders are supported for a named class.
287:             *
288:             * @param className the name of the class.
289:             * @return true if class loaders are supported, false otherwise.
290:             * @throws TurbineException if test fails.
291:             */
292:            public boolean isLoaderSupported(String className)
293:                    throws TurbineException {
294:                Factory factory = getFactory(className);
295:                return factory != null ? factory.isLoaderSupported() : true;
296:            }
297:
298:            /**
299:             * Gets an instance of a specified class.
300:             *
301:             * @param clazz the class.
302:             * @return the instance.
303:             * @throws TurbineException if instantiation fails.
304:             */
305:            protected Object getInstance(Class clazz) throws TurbineException {
306:                try {
307:                    return clazz.newInstance();
308:                } catch (Exception x) {
309:                    throw new TurbineException("Instantiation failed for "
310:                            + clazz.getName(), x);
311:                }
312:            }
313:
314:            /**
315:             * Gets an instance of a specified class.
316:             * Parameters for its constructor are given as an array of objects,
317:             * primitive types must be wrapped with a corresponding class.
318:             *
319:             * @param clazz the class.
320:             * @param params an array containing the parameters of the constructor.
321:             * @param signature an array containing the signature of the constructor.
322:             * @return the instance.
323:             * @throws TurbineException if instantiation fails.
324:             */
325:            protected Object getInstance(Class clazz, Object params[],
326:                    String signature[]) throws TurbineException {
327:                /* Try to construct. */
328:                try {
329:                    Class[] sign = getSignature(clazz, params, signature);
330:                    return clazz.getConstructor(sign).newInstance(params);
331:                } catch (Exception x) {
332:                    throw new TurbineException("Instantiation failed for "
333:                            + clazz.getName(), x);
334:                }
335:            }
336:
337:            /**
338:             * Gets the signature classes for parameters of a method of a class.
339:             *
340:             * @param clazz the class.
341:             * @param params an array containing the parameters of the method.
342:             * @param signature an array containing the signature of the method.
343:             * @return an array of signature classes. Note that in some cases
344:             * objects in the parameter array can be switched to the context
345:             * of a different class loader.
346:             * @throws ClassNotFoundException if any of the classes is not found.
347:             */
348:            public Class[] getSignature(Class clazz, Object params[],
349:                    String signature[]) throws ClassNotFoundException {
350:                if (signature != null) {
351:                    /* We have parameters. */
352:                    ClassLoader tempLoader;
353:                    ClassLoader loader = clazz.getClassLoader();
354:                    Class[] sign = new Class[signature.length];
355:                    for (int i = 0; i < signature.length; i++) {
356:                        /* Check primitive types. */
357:                        sign[i] = getPrimitiveClass(signature[i]);
358:                        if (sign[i] == null) {
359:                            /* Not a primitive one, continue building. */
360:                            if (loader != null) {
361:                                /* Use the class loader of the target object. */
362:                                sign[i] = loader.loadClass(signature[i]);
363:                                tempLoader = sign[i].getClassLoader();
364:                                if ((params[i] != null)
365:                                        && (tempLoader != null)
366:                                        && !tempLoader.equals(params[i]
367:                                                .getClass().getClassLoader())) {
368:                                    /*
369:                                     * The class uses a different class loader,
370:                                     * switch the parameter.
371:                                     */
372:                                    params[i] = switchObjectContext(params[i],
373:                                            loader);
374:                                }
375:                            } else {
376:                                /* Use the default class loader. */
377:                                sign[i] = loadClass(signature[i]);
378:                            }
379:                        }
380:                    }
381:                    return sign;
382:                } else {
383:                    return null;
384:                }
385:            }
386:
387:            /**
388:             * Switches an object into the context of a different class loader.
389:             *
390:             * @param object an object to switch.
391:             * @param loader the loader of the new context.
392:             */
393:            protected Object switchObjectContext(Object object,
394:                    ClassLoader loader) {
395:                ByteArrayOutputStream bout = new ByteArrayOutputStream();
396:                try {
397:                    ObjectOutputStream out = new ObjectOutputStream(bout);
398:                    out.writeObject(object);
399:                    out.flush();
400:                } catch (Exception x) {
401:                    return object;
402:                }
403:
404:                try {
405:                    ByteArrayInputStream bin = new ByteArrayInputStream(bout
406:                            .toByteArray());
407:                    ObjectInputStreamForContext in = new ObjectInputStreamForContext(
408:                            bin, loader);
409:
410:                    return in.readObject();
411:                } catch (Exception x) {
412:                    return object;
413:                }
414:            }
415:
416:            /**
417:             * Loads the named class using the default class loader.
418:             *
419:             * @param className the name of the class to load.
420:             * @return the loaded class.
421:             * @throws ClassNotFoundException if the class was not found.
422:             */
423:            protected Class loadClass(String className)
424:                    throws ClassNotFoundException {
425:                ClassLoader loader = this .getClass().getClassLoader();
426:                try {
427:                    return loader != null ? loader.loadClass(className) : Class
428:                            .forName(className);
429:                } catch (ClassNotFoundException x) {
430:                    /* Go through additional loaders. */
431:                    for (Iterator i = classLoaders.iterator(); i.hasNext();) {
432:                        try {
433:                            return ((ClassLoader) i.next())
434:                                    .loadClass(className);
435:                        } catch (ClassNotFoundException xx) {
436:                        }
437:                    }
438:
439:                    /* Give up. */
440:                    throw x;
441:                }
442:            }
443:
444:            /**
445:             * Loads the named class using a specified class loader.
446:             *
447:             * @param className the name of the class to load.
448:             * @param loader the loader to use.
449:             * @return the loaded class.
450:             * @throws ClassNotFoundException if the class was not found.
451:             */
452:            protected Class loadClass(String className, ClassLoader loader)
453:                    throws ClassNotFoundException {
454:                return loader != null ? loader.loadClass(className)
455:                        : loadClass(className);
456:            }
457:
458:            /**
459:             * Gets a customized factory for a named class.
460:             *
461:             * @param className the name of the class to load.
462:             * @return the factory or null if not specified.
463:             * @throws TurbineException if instantiation of the factory fails.
464:             */
465:            protected Factory getFactory(String className)
466:                    throws TurbineException {
467:                HashMap factories = objectFactories;
468:                Object factory = factories.get(className);
469:                if (factory != null) {
470:                    if (factory instanceof  String) {
471:                        /* Not yet instantiated... */
472:                        try {
473:                            factory = (Factory) getInstance((String) factory);
474:                            ((Factory) factory).init(className);
475:                        } catch (TurbineException x) {
476:                            throw x;
477:                        } catch (ClassCastException x) {
478:                            throw new TurbineException("Incorrect factory "
479:                                    + (String) factory + " for class "
480:                                    + className, x);
481:                        }
482:                        factories = (HashMap) factories.clone();
483:                        factories.put(className, factory);
484:                        objectFactories = factories;
485:                    }
486:                    return (Factory) factory;
487:                } else {
488:                    return null;
489:                }
490:            }
491:        }
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