/* * Copyright (c) 2001 Sun Microsystems, Inc.  All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright *    notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright *    notice, this list of conditions and the following disclaimer in *    the documentation and/or other materials provided with the *    distribution. * * 3. The end-user documentation included with the redistribution, *    if any, must include the following acknowledgment: *       "This product includes software developed by the *       Sun Microsystems, Inc. for Project JXTA." *    Alternately, this acknowledgment may appear in the software itself, *    if and wherever such third-party acknowledgments normally appear. * * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must *    not be used to endorse or promote products derived from this *    software without prior written permission. For written *    permission, please contact Project JXTA at http://www.jxta.org. * * 5. Products derived from this software may not be called "JXTA", *    nor may "JXTA" appear in their name, without prior written *    permission of Sun. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED.  IN NO EVENT SHALL SUN MICROSYSTEMS OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of Project JXTA.  For more * information on Project JXTA, please see * <http://www.jxta.org/>. * * This license is based on the BSD license adopted by the Apache Foundation. * * $Id: ID.java,v 1.34 2005/11/21 19:50:58 bondolo Exp $ */package net.jxta.id;import java.net.URI;import java.net.URL;import java.net.MalformedURLException;import java.net.URISyntaxException;/** *  IDs are used to uniquely identify peers, peer groups, pipes and other *  types of objects manipulated by the JXTA APIs. * *  @see net.jxta.id.IDFactory *  @see net.jxta.codat.CodatID *  @see net.jxta.peer.PeerID *  @see net.jxta.peergroup.PeerGroupID *  @see net.jxta.pipe.PipeID *  @see net.jxta.platform.ModuleClassID *  @see net.jxta.platform.ModuleSpecID *  @see <a href="http://spec.jxta.org/nonav/v1.0/docbook/JXTAProtocols.html#ids" target='_blank'>JXTA Protocols Specification : IDs</a> **/public abstract class ID implements java.io.Serializable {        /**     * This defines the URI scheme that we will be using to present JXTA IDs.     * JXTA IDs are encoded for presentation into URIs (see     * {@link <a href="http://www.ietf.org/rfc/rfc2396.txt">IETF RFC 2396 Uniform Resource Identifiers (URI) : Generic Syntax</a>}     * ) as URNs (see     * {@link <a href="http://www.ietf.org/rfc/rfc2141.txt">IETF RFC 2141 Uniform Resource Names (URN) Syntax</a>}     * ).     **/    public static final String URIEncodingName = "urn";        /**     *  This defines the URN Namespace that we will be using to present JXTA IDs.     *  The namespace allows URN resolvers to determine which sub-resolver to use     *  to resolve URN references. All JXTA IDs are presented in this namespace.     **/    public static final String URNNamespace = "jxta";        /**     *	The null ID. The NullID is often used as a placeholder in fields which     *  are uninitialized.     *     *  <p/>This is a singleton within the scope of a VM.     **/    public static final ID nullID = new NullID();        /**     *     * Creates an ID by parsing the given URI.     *     * <p>This convenience factory method works as if by invoking the     * {@link IDFactory#fromURI(URI)} method; any {@link URISyntaxException}     * thrown is caught and wrapped in a new {@link IllegalArgumentException}     * object, which is then thrown.  </p>     *     * <p> This method is provided for use in situations where it is known that     * the given string is a legal ID, for example for ID constants declared     * within in a program, and so it would be considered a programming error     * for the URI not to parse as such.  The {@link IDFactory}, which throws     * {@link URISyntaxException} directly, should be used situations where a     * ID is being constructed from user input or from some other source that     * may be prone to errors.  </p>     *     * @param  fromURI   The URI to be parsed into an ID     * @return The new ID     *     * @throws  NullPointerException     *          If <tt>fromURI</tt> is <tt>null</tt>     *     * @throws  IllegalArgumentException     *          If the given URI is not a valid ID.     **/    public static ID create( URI fromURI ) {        try {            return IDFactory.fromURI( fromURI );        } catch (URISyntaxException badid) {            IllegalArgumentException failure = new IllegalArgumentException();            failure.initCause( badid );            throw failure;        }    }        /**     *  Constructor for IDs. IDs are constructed using the {@link IDFactory} or     *  {@link #create(URI)}.     *     **/    protected ID() {    }        /**     *  Returns a string representation of the ID. This representation should be     *  used primarily for debugging purposes. For most other situations IDs     *  should be externalized as Java URI Objects via {@link #toURI()}.     *     *  <p/>The default implementation is the <code>toString()</code> of the ID     *  represented as a URI.     *     *  @return	String containing the URI     *     **/    public String toString( ) {        return toURI().toString();    }        /**     *  Returns a string identifier which indicates which ID format is     *  used by this ID instance.     *     *  @return	a string identifier which indicates which ID format is     *  used by this ID instance.     **/    public abstract String getIDFormat();        /**     *  Returns an object containing the unique value of the ID. This object     *  must provide implementations of toString(), equals() and hashCode() that     *  are canonical and consistent from run-to-run given the same input values.     *  Beyond this nothing should be assumed about the nature of this object.     *  For some implementations the object returned may be <code>this</code>.     *     *  @return	Object which can provide canonical representations of the ID.     **/    public abstract Object getUniqueValue();        /**     *  Returns a URL representation of the ID. The     *  {@link net.jxta.id.IDFactory JXTA ID Factory} can be used to construct     *  ID Objects from URLs containing JXTA IDs.     *     *  @deprecated URIs are now the prefered way of manipulating IDs     *     *  @see net.jxta.id.IDFactory#fromURL( java.net.URL )     *     *  @return	URL Object containing the URI     **/    public URL getURL( ) {        try {           return IDFactory.jxtaURL( URIEncodingName, "", URNNamespace + ":" + (String) getUniqueValue() );        } catch( MalformedURLException caught ) {            IllegalStateException failure = new IllegalStateException( "Environment incorrectly intialized." );            failure.initCause( caught );            throw failure;        }    }        /**     *  Returns a URI representation of the ID. {@link java.net.URI URIs} are     *  the prefered way of externalizing and presenting JXTA IDs. The     *  {@link net.jxta.id.IDFactory JXTA ID Factory} can be used to construct     *  ID Objects from URIs containing JXTA IDs.     *     *  @see net.jxta.id.IDFactory#fromURI( java.net.URI )     *     *  @return	URI Object containing the URI     **/    public URI toURI( ) {        return URI.create( URIEncodingName + ":" + URNNamespace + ":" + (String) getUniqueValue()  );    }}/** * The NullID is often used as a placeholder in fields which are uninitialized. */final class NullID extends ID {    final static String JXTAFormat = "jxta";        final static String UNIQUEVALUE = "Null";        /**     *  NullID is not intended to be constructed. You should use the     *  {@link ID.nullID} constant instead.     **/    NullID() {    }        /**     *  {@inheritDoc}     **/    public boolean equals( Object target ) {        return (this == target);   // null is only itself.    }        /**     * deserialization has to point back to the singleton in this VM.     */    private Object readResolve() {        return ID.nullID;    }        /**     *  {@inheritDoc}     **/    public String getIDFormat() {        return JXTAFormat;    }        /**     *  {@inheritDoc}     **/    public Object getUniqueValue() {        return getIDFormat() + "-" + UNIQUEVALUE;    }}