| /* FileBasedPreferences.java -- File-based preference implementation |
| Copyright (C) 2006 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package gnu.java.util.prefs; |
| |
| import gnu.classpath.SystemProperties; |
| |
| import java.io.File; |
| import java.io.FileInputStream; |
| import java.io.FileOutputStream; |
| import java.io.FilenameFilter; |
| import java.io.IOException; |
| import java.nio.channels.FileChannel; |
| import java.nio.channels.FileLock; |
| import java.util.Properties; |
| import java.util.prefs.AbstractPreferences; |
| import java.util.prefs.BackingStoreException; |
| |
| /** |
| * This is a simple file-based preference implementation which writes |
| * the preferences as properties files. A node is represented as a directory |
| * beneath the user's home directory. The preferences for the node are |
| * stored in a single properties file in that directory. Sub-nodes are |
| * stored in subdirectories. This implementation uses file locking to |
| * mediate access to the properties files. |
| */ |
| public class FileBasedPreferences |
| extends AbstractPreferences |
| { |
| /** |
| * Name of the property file storing the data in a given directory. |
| */ |
| private static final String DATA_FILE = "data.properties"; |
| |
| /** |
| * The directory corresponding to this preference node. |
| */ |
| private File directory; |
| |
| /** |
| * The file holding the data for this node. |
| */ |
| private File dataFile; |
| |
| /** |
| * The data in this node. |
| */ |
| private Properties properties; |
| |
| /** |
| * Create the root node for the file-based preferences. |
| */ |
| FileBasedPreferences() |
| { |
| super(null, ""); |
| String home = SystemProperties.getProperty("user.home"); |
| this.directory = new File(new File(home, ".classpath"), "userPrefs"); |
| this.dataFile = new File(this.directory, DATA_FILE); |
| load(); |
| } |
| |
| /** |
| * Create a new file-based preference object with the given parent |
| * and the given name. |
| * @param parent the parent |
| * @param name the name of this node |
| */ |
| FileBasedPreferences(FileBasedPreferences parent, String name) |
| { |
| super(parent, name); |
| this.directory = new File(parent.directory, name); |
| this.dataFile = new File(this.directory, DATA_FILE); |
| load(); |
| } |
| |
| private void load() |
| { |
| this.properties = new Properties(); |
| FileInputStream fis = null; |
| FileLock lock = null; |
| try |
| { |
| fis = new FileInputStream(this.dataFile); |
| FileChannel channel = fis.getChannel(); |
| lock = channel.lock(0, Long.MAX_VALUE, true); |
| this.properties.load(fis); |
| // We release the lock and close the stream in the 'finally' |
| // clause. |
| } |
| catch (IOException _) |
| { |
| // We don't mind; this means we're making a new node. |
| newNode = true; |
| } |
| finally |
| { |
| try |
| { |
| // Release the lock and close the stream. |
| if (lock != null) |
| lock.release(); |
| } |
| catch (IOException ignore) |
| { |
| // Ignore. |
| } |
| try |
| { |
| // Close the stream. |
| if (fis != null) |
| fis.close(); |
| } |
| catch (IOException ignore) |
| { |
| // Ignore. |
| } |
| } |
| } |
| |
| public boolean isUserNode() |
| { |
| // For now file preferences are always user nodes. |
| return true; |
| } |
| |
| protected String[] childrenNamesSpi() throws BackingStoreException |
| { |
| // FIXME: security manager. |
| String[] result = directory.list(new FilenameFilter() |
| { |
| public boolean accept(File dir, String name) |
| { |
| return new File(dir, name).isDirectory(); |
| } |
| }); |
| if (result == null) |
| result = new String[0]; |
| return result; |
| } |
| |
| protected AbstractPreferences childSpi(String name) |
| { |
| return new FileBasedPreferences(this, name); |
| } |
| |
| protected String[] keysSpi() throws BackingStoreException |
| { |
| return (String[]) properties.keySet().toArray(new String[0]); |
| } |
| |
| protected String getSpi(String key) |
| { |
| return properties.getProperty(key); |
| } |
| |
| protected void putSpi(String key, String value) |
| { |
| properties.put(key, value); |
| } |
| |
| protected void removeSpi(String key) |
| { |
| properties.remove(key); |
| } |
| |
| protected void flushSpi() throws BackingStoreException |
| { |
| // FIXME: security manager. |
| try |
| { |
| if (isRemoved()) |
| { |
| // Delete the underlying file. |
| // FIXME: ideally we would also delete the directory |
| // if it had no subdirectories. This doesn't matter |
| // much though. |
| // FIXME: there's a strange race here if a different VM is |
| // simultaneously updating this node. |
| dataFile.delete(); |
| } |
| else |
| { |
| // Write the underlying file. |
| directory.mkdirs(); |
| |
| FileOutputStream fos = null; |
| FileLock lock = null; |
| try |
| { |
| // Note that we let IOExceptions from the try clause |
| // propagate to the outer 'try'. |
| fos = new FileOutputStream(dataFile); |
| FileChannel channel = fos.getChannel(); |
| lock = channel.lock(); |
| properties.store(fos, "created by GNU Classpath FileBasedPreferences"); |
| // Lock is released and file closed in the finally clause. |
| } |
| finally |
| { |
| try |
| { |
| if (lock != null) |
| lock.release(); |
| } |
| catch (IOException _) |
| { |
| // Ignore. |
| } |
| try |
| { |
| if (fos != null) |
| fos.close(); |
| } |
| catch (IOException _) |
| { |
| // Ignore. |
| } |
| } |
| } |
| } |
| catch (IOException ioe) |
| { |
| throw new BackingStoreException(ioe); |
| } |
| } |
| |
| protected void syncSpi() throws BackingStoreException |
| { |
| // FIXME: we ought to synchronize but instead we merely flush. |
| flushSpi(); |
| } |
| |
| protected void removeNodeSpi() throws BackingStoreException |
| { |
| // We can simply delegate. |
| flushSpi(); |
| } |
| } |