Is there a way to use java.util.Preferences under Windows without it using the Registry as the backend?

Question

I want to use the java.util.Preferences API but I don't want my program to attempt to read or write to the Windows registry. How would I go about this?

Answer 1

I trust you have read the read/write to Windows Registry using Java and you then want to have another back-end than the registry when using the java.util.Preferences API

You could extend the Preference API, like Bernhard or Croft did, as described in this article:

Because the Preferences API is back-end neutral, you need not care whether the data are stored in files, database tables, or a platform-specific storage such as the Windows Registry.

Examples of extensions through new Preferences can be seen here.

That is better, IMO, than to use another API.

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For instance, searching for classes extending java.util.prefs.AbstractPreferences:

• You can use a preference store backed by an XML file:

de.unika.ipd.grgen.util.MyPreferences

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.prefs.AbstractPreferences;
import java.util.prefs.BackingStoreException;

/**
 * Own implementation of the Java preferences API, that does not use
 * a "OS backing store" but relies on importing and exporting the
 * preferences via xml files.
 * Also, If a preference is got, but was not in the tree, it is entered.
 */
public class MyPreferences extends AbstractPreferences {

    private Map<String, String> prefs = new HashMap<String, String>();
    private Map<String, AbstractPreferences> children = new HashMap<String, AbstractPreferences>();

  public MyPreferences(MyPreferences parent, String name) {
    super(parent, name);
  }

  /**
   * @see java.util.prefs.AbstractPreferences#putSpi(java.lang.String, java.lang.String)
   */
  protected void putSpi(String key, String value) {
    prefs.put(key, value);
  }

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• Or you could store those preferences in an LDAP:

de.tarent.ldap.prefs.LDAPSystemPreferences

import java.util.prefs.AbstractPreferences;
import java.util.prefs.BackingStoreException;

import javax.naming.NamingException;
import javax.naming.directory.Attributes;

import de.tarent.ldap.LDAPException;
import de.tarent.ldap.LDAPManager;

/**
 * @author kirchner
 * 
 * Preferences im LDAP
 */
public class LDAPSystemPreferences extends AbstractPreferences {
    LDAPManager     ldm         = null;
    Properties      properties  = new Properties();
    //Map für key/value der Preferences
    Map             cache       = new HashMap();
    //Map für timestamp der Preferences
    Map             timestamp   = new HashMap();
    private Boolean deleted     = Boolean.FALSE;

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• Or you can use a simple property file:

com.adito.boot.PropertyPreferences:

import java.util.prefs.AbstractPreferences;
import java.util.prefs.BackingStoreException;
import java.util.prefs.Preferences;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;


/**
 * A simple implementation for the preferences API. That stores preferences
 * in propery files. We do not have to worry about sharing the preferencese 
 * with other JVM instance so there is no need for any kind of synchronising
 * or locking.
 */
public class PropertyPreferences extends AbstractPreferences {

Answer 2

It is always possible to extend java.util.prefs.AbstractPreferences.

An alternative could be to use The Configuration package of Apache Commons allows you to read and write configuration data from/to different sources.