Source Code Cross Referenced for AbstractAbstractFile.java in  » Scripting » oscript-2.10.4 » oscript » fs » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Scripting » oscript 2.10.4 » oscript.fs 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*=============================================================================
002:         *     Copyright Texas Instruments 2003.  All Rights Reserved.
003:         *   
004:         * This program is free software; you can redistribute it and/or
005:         * modify it under the terms of the GNU Lesser General Public
006:         * License as published by the Free Software Foundation; either
007:         * version 2 of the License, or (at your option) any later version.
008:         * 
009:         * This program is distributed in the hope that it will be useful,
010:         * but WITHOUT ANY WARRANTY; without even the implied warranty of
011:         * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
012:         * Lesser General Public License for more details.
013:         * 
014:         * You should have received a copy of the GNU Lesser General Public
015:         * License along with this library; if not, write to the Free Software
016:         * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
017:         */
018:
019:        package oscript.fs;
020:
021:        import java.io.*;
022:        import java.util.*;
023:
024:        import oscript.exceptions.ProgrammingErrorException;
025:
026:        /**
027:         * Abstract implementation of {@link AbstractFile}... hmm, the naming scheme 
028:         * isn't working out so well here, because AbstractFile. isn't a good name 
029:         * for an interface.
030:         * 
031:         * @author Rob Clark (rob@ti.com)
032:         */
033:        public abstract class AbstractAbstractFile implements  AbstractFile,
034:                Serializable {
035:            private String ext;
036:            private String path;
037:
038:            private static TempFileSystem tfs = new TempFileSystem();
039:
040:            static {
041:                AbstractFileSystem.mount(tfs, tfs.getMountPath());
042:            }
043:
044:            /**
045:             * Class Constructor.  If this file is created as a temporary file (ie.
046:             * <code>temp</code> is <code>true</code>), then the <code>path</code>
047:             * is interpreted as a relative path, or filename with no path prefix,
048:             * and the file is created with a unique directory path, and the file
049:             * will not {@link #equals} any other file object.
050:             * 
051:             * @param path        the file name
052:             * @param temp        is this a unique temporary file
053:             */
054:            public AbstractAbstractFile(String path, boolean temp) {
055:                String subpath = null;
056:
057:                if (temp) {
058:                    subpath = Math.random() + "/" + path;
059:                    path = tfs.getMountPath() + "/" + subpath;
060:                }
061:
062:                path = AbstractFileSystem.normalize(path);
063:
064:                this .path = path;
065:
066:                int idx = path.lastIndexOf('.');
067:                if (idx != -1)
068:                    ext = path.substring(idx + 1);
069:                else
070:                    ext = "";
071:
072:                /* note that only temp files get registered, because tfs only handles
073:                 * things under /tmp... if tfs handled the entire filesystem space,
074:                 * then it would need to be involved in any sort of resolve/children
075:                 * operation, which for now I am staying away from for performance
076:                 * reasons... plus at this point non-temp AbstractAbstractFile's are
077:                 * a very special case.
078:                 */
079:                if (temp)
080:                    tfs.registerFile(subpath, this );
081:            }
082:
083:            /**
084:             * Is it possible to write to this file.
085:             */
086:            public boolean canWrite() {
087:                return false;
088:            }
089:
090:            /**
091:             * Is it possible to read from this file.
092:             */
093:            public boolean canRead() {
094:                return true;
095:            }
096:
097:            /**
098:             * Tests whether the file denoted by this abstract pathname exists.
099:             *
100:             * @return  <code>true</code> iff the file exists
101:             */
102:            public boolean exists() {
103:                return true;
104:            }
105:
106:            /**
107:             * Test whether this file is a directory.
108:             * 
109:             * @return <code>true</code> iff this file is a directory
110:             */
111:            public boolean isDirectory() {
112:                return false;
113:            }
114:
115:            /**
116:             * Test whether this file is a regular file.  A file is a regular file if
117:             * it is not a directory.
118:             * 
119:             * @return <code>true</code> iff this file is a regular file.
120:             */
121:            public boolean isFile() {
122:                return true;
123:            }
124:
125:            /**
126:             * Return the time of last modification.  The meaning of these value is not
127:             * so important, but the implementation must ensure that a higher value is
128:             * returned for the more recent version of a given element.  Ie. if at some
129:             * point this returns X, an <code>AbstractFile</code> representing the same
130:             * "file", but created at a later time, should return X if the file has not
131:             * been modified, or >X if the file has been modified.
132:             *
133:             * @return larger value indicates more recent modification
134:             */
135:            public long lastModified() {
136:                return 0; // prehaps construction time?
137:            }
138:
139:            /**
140:             * should be overriden to not provide a bogus answer
141:             */
142:            public long length() {
143:                return -1;
144:            }
145:
146:            /**
147:             * Create a new empty file, if it does not yet exist.
148:             *
149:             * @return <code>true</code> iff the file does not exist and was successfully
150:             * created.
151:             * @throws IOException if error
152:             */
153:            public boolean createNewFile() throws IOException {
154:                throw new IOException("unsupported");
155:            }
156:
157:            /**
158:             * Update the timestamp on this file to the current time.
159:             * 
160:             * @throws IOException if error
161:             */
162:            public void touch() throws IOException {
163:                throw new IOException("unsupported");
164:            }
165:
166:            /**
167:             * Delete this file.  If this file is a directory, then the directory must
168:             * be empty.
169:             * 
170:             * @return <code>true<code> iff the directory is successfully deleted.
171:             * @throws IOException if error
172:             */
173:            public boolean delete() throws IOException {
174:                throw new IOException("unsupported");
175:            }
176:
177:            /**
178:             * If this file does not exist, create it as a directory.
179:             * 
180:             * @return <code>true</code> iff directory successfully created
181:             */
182:            public boolean mkdir() throws IOException {
183:                throw new IOException("unsupported");
184:            }
185:
186:            /**
187:             * If this file does not exist, create it as a directory.  All necessary
188:             * parent directories are also created.  If this operation fails, it may
189:             * have successfully created some or all of the parent directories.
190:             * 
191:             * @return <code>true</code> iff directory successfully created
192:             */
193:            public boolean mkdirs() throws IOException {
194:                throw new IOException("unsupported");
195:            }
196:
197:            /**
198:             * Get an output stream to write to this file.
199:             *
200:             * @return output stream
201:             * @throws IOException if <code>canWrite</code> returns <code>false</code>
202:             * @see #canWrite
203:             */
204:            public OutputStream getOutputStream(boolean append)
205:                    throws IOException {
206:                throw new IOException("unsupported");
207:            }
208:
209:            /**
210:             * Get the extension, which indicates the type of file.  Usually the extension
211:             * is part of the filename, ie. if the extension was <i>os</i>, the filename
212:             * would end with <i>.os</i>.
213:             *
214:             * @return a string indicating the type of file
215:             */
216:            public String getExtension() {
217:                return ext;
218:            }
219:
220:            /**
221:             * Get the file path, which globally identifies the file.
222:             * 
223:             * @return a unique string
224:             * @see #getName
225:             */
226:            public String getPath() {
227:                return path;
228:            }
229:
230:            /**
231:             * Get the name of this file, which is the last component of the complete path.
232:             * 
233:             * @return the file name
234:             * @see #getPath
235:             */
236:            public String getName() {
237:                int idx = path.lastIndexOf("/");
238:                if (idx != -1)
239:                    return path.substring(idx + 1);
240:                else
241:                    return path;
242:            }
243:
244:            public String toString() {
245:                return getPath();
246:            }
247:
248:            public int hashCode() {
249:                return getPath().hashCode();
250:            }
251:
252:            public boolean equals(Object obj) {
253:                return (obj instanceof  AbstractFile)
254:                        && ((AbstractFile) obj).getPath().equals(getPath());
255:            }
256:        }
257:
258:        /**
259:         * The filesystem which enables temp files to appear in the filesystem.  It 
260:         * holds weak-references to the temp files that get created, in order to
261:         * track what temp files are currently live.
262:         */
263:        class TempFileSystem extends AbstractFileSystem {
264:            static java.lang.ref.ReferenceQueue rq = new java.lang.ref.ReferenceQueue();
265:
266:            /**
267:             * table of files currently registered with the tmp filesystem
268:             */
269:            private Hashtable fileTable = new Hashtable();
270:
271:            /**
272:             * Class constructor.
273:             */
274:            TempFileSystem() {
275:                oscript.util.WorkerThread.addRunnable(new Runnable() {
276:                    public void run() {
277:                        AbstractFileReference afr;
278:                        while ((afr = (AbstractFileReference) (rq.poll())) != null)
279:                            afr.cleanup();
280:                    }
281:                }, 500);
282:            }
283:
284:            /**
285:             * Get the path to where this filesystem should be mounted.
286:             */
287:            String getMountPath() {
288:                return "/.tmp";
289:            }
290:
291:            /**
292:             * Register a file that is created within this filesystem's space
293:             */
294:            AbstractFileReference registerFile(String subpath, AbstractFile file) {
295:                synchronized (fileTable) {
296:                    AbstractFileReference afr = new AbstractFileReference(
297:                            subpath, file);
298:                    fileTable.put(subpath, afr);
299:                    return afr;
300:                }
301:            }
302:
303:            /**
304:             * A weak-reference for tracking the file.
305:             */
306:            class AbstractFileReference extends java.lang.ref.WeakReference {
307:                private String subpath;
308:                private AbstractFile parent;
309:                private AbstractFileReference parentRef;
310:
311:                AbstractFileReference(String subpath, AbstractFile file) {
312:                    super (file, rq);
313:                    this .subpath = subpath;
314:
315:                    int idx = subpath.lastIndexOf('/');
316:                    if (idx != -1) {
317:                        String parentSubpath = subpath.substring(0, idx);
318:                        parent = new BogusFile(getMountPath() + "/"
319:                                + parentSubpath, true, true, false);
320:                        parentRef = registerFile(parentSubpath, parent);
321:                    }
322:                }
323:
324:                String getSubpath() {
325:                    return subpath;
326:                }
327:
328:                AbstractFile getFile() {
329:                    return (AbstractFile) get();
330:                }
331:
332:                void cleanup() {
333:                    synchronized (fileTable) {
334:                        if (parentRef != null)
335:                            parentRef.cleanup();
336:                        fileTable.remove(getSubpath());
337:                    }
338:                }
339:            }
340:
341:            /**
342:             * Try to resolve the specified path.  If unresolved, return <code>null</code>.
343:             * 
344:             * @param mountPath    the path this fs is mounted at to resolve the requested file
345:             * @param subpath         path to file, relative to <code>mountPath</code>
346:             * @return file or <code>null</code>
347:             */
348:            protected AbstractFile resolveInFileSystem(String mountPath,
349:                    String subpath) throws IOException {
350:                if (!mountPath.equals(getMountPath()))
351:                    throw new ProgrammingErrorException(
352:                            "this shouldn't happen!  send this error msg to rob@ti.com");
353:
354:                synchronized (fileTable) {
355:                    AbstractFileReference afr = (AbstractFileReference) (fileTable
356:                            .get(subpath));
357:
358:                    if (afr != null)
359:                        return afr.getFile();
360:                }
361:
362:                return null;
363:            }
364:
365:            /**
366:             * Return an iterator of children of the specified path.
367:             * 
368:             * @param mountPath    the path this fs is mounted at to resolve the requested file
369:             * @param subpath         path to file, relative to <code>mountPath</code>
370:             * @return an iterator of <code>AbstractFile</code>
371:             */
372:            protected Collection childrenInFileSystem(String mountPath,
373:                    String subpath) throws IOException {
374:                LinkedList fileList = new LinkedList();
375:
376:                synchronized (fileTable) {
377:                    for (Iterator itr = fileTable.values().iterator(); itr
378:                            .hasNext();) {
379:                        AbstractFileReference afr = (AbstractFileReference) (itr
380:                                .next());
381:                        String afrpath = afr.getSubpath();
382:                        // XXX this assumes the paths are properly normalized...
383:                        if (afrpath.startsWith(subpath)
384:                                && (afrpath.length() > subpath.length())
385:                                && (afrpath.indexOf('/', subpath.length() + 1) == -1)) {
386:                            AbstractFile file = afr.getFile();
387:                            if (file != null)
388:                                fileList.add(file);
389:                        }
390:                    }
391:                }
392:
393:                return fileList;
394:            }
395:
396:            /**
397:             * Flush any pending changes within this filesystem.
398:             */
399:            protected void flush() throws IOException {
400:                /* no-op */
401:            }
402:        }
403:
404:        /*
405:         *   Local Variables:
406:         *   tab-width: 2
407:         *   indent-tabs-mode: nil
408:         *   mode: java
409:         *   c-indentation-style: java
410:         *   c-basic-offset: 2
411:         *   eval: (c-set-offset 'substatement-open '0)
412:         *   eval: (c-set-offset 'case-label '+)
413:         *   eval: (c-set-offset 'inclass '+)
414:         *   eval: (c-set-offset 'inline-open '0)
415:         *   End:
416:         */
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