FileBasedPreferences

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gnu.java.util.prefs
Class FileBasedPreferences

java.lang.Object
  java.util.prefs.Preferences
      java.util.prefs.AbstractPreferences
          gnu.java.util.prefs.FileBasedPreferences

public class FileBasedPreferences
extends java.util.prefs.AbstractPreferences

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.

Field Summary

private static java.lang.String DATA_FILE
          Name of the property file storing the data in a given directory.

private java.io.File dataFile
          The file holding the data for this node.

private java.io.File directory
          The directory corresponding to this preference node.

private java.util.Properties properties
          The data in this node.

Fields inherited from class java.util.prefs.AbstractPreferences

lock, newNode

Fields inherited from class java.util.prefs.Preferences

MAX_KEY_LENGTH, MAX_NAME_LENGTH, MAX_VALUE_LENGTH

Constructor Summary

(package private) FileBasedPreferences()
          Create the root node for the file-based preferences.

(package private) FileBasedPreferences(FileBasedPreferences parent, java.lang.String name)
          Create a new file-based preference object with the given parent and the given name.

Method Summary

protected java.lang.String[] childrenNamesSpi()
          Returns the names of the sub nodes of this preference node.

protected java.util.prefs.AbstractPreferences childSpi(java.lang.String name)
          Returns a child note with the given name.

protected void flushSpi()
          Writes all entries of this preferences node that have not yet been written to the backing store and possibly creates this node in the backing store, if it does not yet exist.

protected java.lang.String getSpi(java.lang.String key)
          Returns the value associated with the key in this preferences node or null when the key does not exist in this preferences node.

boolean isUserNode()
          Returns true if this node comes from the user preferences tree, false if it comes from the system preferences tree.

protected java.lang.String[] keysSpi()
          Returns an (possibly empty) array with all the keys of the preference entries of this node.

private void load()


protected void putSpi(java.lang.String key, java.lang.String value)
          Sets the value of the given preferences entry for this node.

protected void removeNodeSpi()
          Clears this node from this VM and removes it from the backing store.

protected void removeSpi(java.lang.String key)
          Removes the given key entry from this preferences node.

protected void syncSpi()
          Writes all entries of this preferences node that have not yet been written to the backing store and reads any entries that have changed in the backing store but that are not yet visible in this VM.

Methods inherited from class java.util.prefs.AbstractPreferences

absolutePath, addNodeChangeListener, addPreferenceChangeListener, cachedChildren, childrenNames, clear, exportNode, exportSubtree, flush, get, getBoolean, getByteArray, getChild, getDouble, getFloat, getInt, getLong, isRemoved, keys, name, node, nodeExists, parent, put, putBoolean, putByteArray, putDouble, putFloat, putInt, putLong, remove, removeNode, removeNodeChangeListener, removePreferenceChangeListener, sync, toString

Methods inherited from class java.util.prefs.Preferences

importPreferences, systemNodeForPackage, systemRoot, userNodeForPackage, userRoot

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

DATA_FILE

private static final java.lang.String DATA_FILE

Name of the property file storing the data in a given directory.

See Also:: Constant Field Values

dataFile

private java.io.File dataFile

The file holding the data for this node.

properties

private java.util.Properties properties

The data in this node.

Constructor Detail

FileBasedPreferences

FileBasedPreferences()

Create the root node for the file-based preferences.

FileBasedPreferences

FileBasedPreferences(FileBasedPreferences parent,
                     java.lang.String name)

Create a new file-based preference object with the given parent and the given name.

Method Detail