Source Code Cross Referenced for Extension.java in  » Mail-Clients » columba-1.4 » org » columba » core » plugin » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Mail Clients » columba 1.4 » org.columba.core.plugin 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        // The contents of this file are subject to the Mozilla Public License Version
002:        // 1.1
003:        //(the "License"); you may not use this file except in compliance with the
004:        //License. You may obtain a copy of the License at http://www.mozilla.org/MPL/
005:        //
006:        //Software distributed under the License is distributed on an "AS IS" basis,
007:        //WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
008:        //for the specific language governing rights and
009:        //limitations under the License.
010:        //
011:        //The Original Code is "The Columba Project"
012:        //
013:        //The Initial Developers of the Original Code are Frederik Dietz and Timo
014:        // Stich.
015:        //Portions created by Frederik Dietz and Timo Stich are Copyright (C) 2003.
016:        //
017:        //All Rights Reserved.
018:        package org.columba.core.plugin;
019:
020:        import java.io.File;
021:        import java.lang.reflect.Constructor;
022:        import java.net.MalformedURLException;
023:        import java.net.URL;
024:        import java.util.List;
025:        import java.util.Vector;
026:
027:        import org.columba.api.plugin.ExtensionMetadata;
028:        import org.columba.api.plugin.IExtension;
029:        import org.columba.api.plugin.IExtensionInterface;
030:        import org.columba.api.plugin.PluginException;
031:        import org.columba.api.plugin.PluginMetadata;
032:        import org.columba.core.logging.Logging;
033:        import org.columba.core.main.Main;
034:
035:        /**
036:         * An extension providing the metadata of an extension and the runtime context
037:         * for instanciation.
038:         * 
039:         * @author fdietz
040:         */
041:        public class Extension implements  IExtension {
042:
043:            private static final String FILE_PLUGIN_JAR = "plugin.jar";
044:
045:            private static final java.util.logging.Logger LOG = java.util.logging.Logger
046:                    .getLogger("org.columba.core.plugin");
047:
048:            private ExtensionMetadata metadata;
049:
050:            private PluginMetadata pluginMetadata;
051:
052:            private boolean internalPlugin;
053:
054:            private IExtensionInterface cachedInstance;
055:
056:            /**
057:             * Enabled by default. But, in case of an error on instanciation its
058:             * disabled.
059:             */
060:            private boolean enabled = true;
061:
062:            /**
063:             * Constructor used by internal extensions
064:             * 
065:             * @param metadata
066:             */
067:            public Extension(ExtensionMetadata metadata, boolean internal) {
068:                this .metadata = metadata;
069:
070:                internalPlugin = internal;
071:            }
072:
073:            /**
074:             * Constructor used by external extensions.
075:             * 
076:             * @param pluginMetadata
077:             * @param metadata
078:             */
079:            public Extension(PluginMetadata pluginMetadata,
080:                    ExtensionMetadata metadata) {
081:                this .metadata = metadata;
082:                this .pluginMetadata = pluginMetadata;
083:
084:                internalPlugin = false;
085:            }
086:
087:            /**
088:             * @see org.columba.api.plugin.IExtension#getMetadata()
089:             */
090:            public ExtensionMetadata getMetadata() {
091:                return metadata;
092:            }
093:
094:            /**
095:             * @see org.columba.api.plugin.IExtension#instanciateExtension(java.lang.Object[])
096:             */
097:            public IExtensionInterface instanciateExtension(Object[] arguments)
098:                    throws PluginException {
099:
100:                if (!enabled)
101:                    throw new PluginException(
102:                            "Extension <"
103:                                    + getMetadata().getId()
104:                                    + "> was disabled due to a former instanciation error");
105:
106:                String id = null;
107:                File pluginDirectory = null;
108:
109:                String className = metadata.getClassname();
110:
111:                if (pluginMetadata != null) {
112:                    id = pluginMetadata.getId();
113:                    // if external plugin, we need the directory of it
114:                    pluginDirectory = pluginMetadata.getDirectory();
115:                }
116:
117:                IExtensionInterface plugin = null;
118:
119:                // if available, load cached instance
120:                if ((metadata.isSingleton()) && (cachedInstance != null)) {
121:                    plugin = cachedInstance;
122:
123:                } else {
124:
125:                    try {
126:
127:                        if (isInternal())
128:
129:                            // use default Java classlodaer
130:                            plugin = instanciateJavaClass(className, arguments);
131:
132:                        else {
133:                            //
134:                            // external plugin
135:                            //				
136:
137:                            // just in case that someone who developers on a plugin
138:                            // adds the plugin files to his classpath, we try to
139:                            // load
140:                            // them with the default classloader
141:
142:                            // use default Java classlodaer
143:
144:                            // try {
145:                            // plugin = instanciateJavaClass(className, arguments);
146:                            // if (plugin != null)
147:                            // return plugin;
148:                            //
149:                            // } catch (Exception e) {
150:                            // //handleException(e);
151:                            // } catch (Error e) {
152:                            // //handleException(e);
153:                            // }
154:
155:                            // use external Java URL classloader
156:                            plugin = instanciateExternalJavaClass(arguments,
157:                                    pluginDirectory, className);
158:
159:                        }
160:
161:                        // remember instance
162:                        if (metadata.isSingleton())
163:                            cachedInstance = plugin;
164:
165:                    } catch (Exception e) {
166:                        logErrorMessage(e);
167:
168:                        // disable extension
169:                        enabled = false;
170:
171:                        throw new PluginException(this , e);
172:                    } catch (Error e) {
173:                        logErrorMessage(e);
174:
175:                        // disable extension
176:                        enabled = false;
177:
178:                        throw new PluginException(this , e);
179:                    }
180:
181:                }
182:                return plugin;
183:            }
184:
185:            /**
186:             * @param e
187:             */
188:            private void logErrorMessage(Throwable e) {
189:                if (e.getCause() != null) {
190:                    LOG.severe(e.getCause().getMessage());
191:                    if (Logging.DEBUG)
192:                        e.getCause().printStackTrace();
193:                } else {
194:                    LOG.severe(e.getMessage());
195:                    if (Logging.DEBUG)
196:                        e.printStackTrace();
197:                }
198:            }
199:
200:            /**
201:             * Instanciate external Java class which is specified using the
202:             * <code>plugin.xml</code> descriptor file.
203:             * <p>
204:             * Currently, this is not used!
205:             * 
206:             * @param arguments
207:             *            class constructor arguments
208:             * @param pluginDirectory
209:             *            plugin directory
210:             * @param className
211:             *            extension classname
212:             * @return extension instance
213:             * @throws Exception
214:             */
215:            private IExtensionInterface instanciateExternalJavaClass(
216:                    Object[] arguments, File pluginDirectory, String className)
217:                    throws Exception {
218:                IExtensionInterface plugin;
219:                URL[] urls = null;
220:
221:                // all Java plugins package their class-files in "plugin.jar"
222:                String jarFilename = Extension.FILE_PLUGIN_JAR;
223:
224:                try {
225:                    urls = getURLs(pluginDirectory, jarFilename);
226:                } catch (MalformedURLException e) {
227:                    // should never happen
228:                    e.printStackTrace();
229:                }
230:
231:                //
232:                // @author: fdietz
233:                // WORKAROUND:
234:                // we simply append URLs to the existing global class loader
235:                // and use the same as parent
236:                // 
237:                // Note, that we create a new URL classloader for every class
238:                // we instanciate. We might want to support hot-swapping
239:                // of changed classes later.
240:
241:                // append URLs to global classloader
242:                Main.mainClassLoader.addURLs(urls);
243:
244:                //plugin = instanciateJavaClass(className, arguments);
245:
246:                // create new class loader using the global class loader as parent
247:                ExternalClassLoader loader = new ExternalClassLoader(urls,
248:                        Main.mainClassLoader);
249:                plugin = (IExtensionInterface) loader.instanciate(className,
250:                        arguments);
251:
252:                return plugin;
253:            }
254:
255:            private IExtensionInterface instanciateJavaClass(String className,
256:                    Object[] arguments) throws Exception {
257:
258:                if (className == null)
259:                    throw new IllegalArgumentException("className == null");
260:
261:                IExtensionInterface plugin = null;
262:
263:                // use our global class loader
264:                ClassLoader loader = Main.mainClassLoader;
265:
266:                Class actClass;
267:
268:                actClass = loader.loadClass(className);
269:
270:                //
271:                // we can't just load the first constructor
272:                // -> go find the correct constructor based
273:                // -> based on the arguments
274:                //
275:                if ((arguments == null) || (arguments.length == 0)) {
276:
277:                    plugin = (IExtensionInterface) actClass.newInstance();
278:
279:                } else {
280:                    Constructor constructor;
281:
282:                    constructor = ClassLoaderHelper.findConstructor(arguments,
283:                            actClass);
284:
285:                    // couldn't find correct constructor
286:                    if (constructor == null) {
287:                        LOG.severe("Couldn't find constructor for " + className
288:                                + " with matching argument-list: ");
289:                        for (int i = 0; i < arguments.length; i++) {
290:                            LOG.severe("argument[" + i + "]=" + arguments[i]);
291:                        }
292:
293:                        return null;
294:                    } else {
295:
296:                        plugin = (IExtensionInterface) constructor
297:                                .newInstance(arguments);
298:
299:                    }
300:
301:                }
302:
303:                return plugin;
304:            }
305:
306:            /**
307:             * @see org.columba.api.plugin.IExtension#isInternal()
308:             */
309:            public boolean isInternal() {
310:                return internalPlugin;
311:            }
312:
313:            /**
314:             * @see java.lang.Object#toString()
315:             */
316:            public String toString() {
317:                StringBuffer buf = new StringBuffer();
318:                buf.append("id=" + metadata.getId());
319:                buf.append("class=" + metadata.getClassname());
320:
321:                return buf.toString();
322:            }
323:
324:            /**
325:             * Generate array of all URLs which are used to prefill the URLClassloader.
326:             * <p>
327:             * All jar-files in /lib directory are automatically added.
328:             * 
329:             * @param file
330:             *            plugin directory
331:             * @param jarFile
332:             *            jar-file containing the extension code
333:             * @return URL array
334:             * @throws MalformedURLException
335:             */
336:            private URL[] getURLs(File file, String jarFile)
337:                    throws MalformedURLException {
338:                if (file == null)
339:                    throw new IllegalArgumentException("file == null");
340:                if (jarFile == null)
341:                    throw new IllegalArgumentException("jarFile == null");
342:
343:                List urlList = new Vector();
344:
345:                // plugin-directory
346:                String path = file.getPath();
347:
348:                if (jarFile != null) {
349:                    URL jarURL = new File(file, jarFile).toURL();
350:                    urlList.add(jarURL);
351:                }
352:
353:                URL newURL = new File(path).toURL();
354:                urlList.add(newURL);
355:
356:                // we add every jar-file in /lib, too
357:                // plugin-directory
358:
359:                File lib = new File(file, "lib");
360:
361:                if (lib.exists()) {
362:                    File[] libList = lib.listFiles();
363:
364:                    for (int i = 0; i < libList.length; i++) {
365:                        File f = libList[i];
366:
367:                        if (f.getName().endsWith(".jar")) {
368:                            // jar-file found
369:                            urlList.add(f.toURL());
370:                        } else if (f.isDirectory()) {
371:                            urlList.add(f.toURL());
372:                        }
373:                    }
374:                }
375:
376:                URL[] url = new URL[urlList.size()];
377:
378:                for (int i = 0; i < urlList.size(); i++) {
379:                    url[i] = (URL) urlList.get(i);
380:                }
381:
382:                if (Logging.DEBUG) {
383:                    for (int i = 0; i < url.length; i++) {
384:                        LOG.finest("url[" + i + "]=" + url[i]);
385:                    }
386:                }
387:
388:                return url;
389:            }
390:
391:            public void setInternal(boolean internal) {
392:                this .internalPlugin = internal;
393:            }
394:
395:            /**
396:             * Returns enabled by default. But, in case of an error on instanciation its
397:             * disabled.
398:             *
399:             * @return enabled by default. But, in case of an error on instanciation its
400:             */
401:            public boolean isEnabled() {
402:                // TODO Auto-generated method stub
403:                return false;
404:            }
405:
406:        }
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