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Diffstat (limited to 'gcc-4.4.3/libjava/classpath/gnu/java/util/prefs/FileBasedPreferences.java')
| -rw-r--r-- | gcc-4.4.3/libjava/classpath/gnu/java/util/prefs/FileBasedPreferences.java | 273 |
1 files changed, 273 insertions, 0 deletions
diff --git a/gcc-4.4.3/libjava/classpath/gnu/java/util/prefs/FileBasedPreferences.java b/gcc-4.4.3/libjava/classpath/gnu/java/util/prefs/FileBasedPreferences.java new file mode 100644 index 000000000..f7566dddd --- /dev/null +++ b/gcc-4.4.3/libjava/classpath/gnu/java/util/prefs/FileBasedPreferences.java @@ -0,0 +1,273 @@ +/* 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(); + } +} |