id.java

jxme的一些相关程序,主要是手机上程序开发以及手机和计算机通信的一些程序资料,程序编译需要Ant支持

/*
 * 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 1.2 2002/03/04 20:19:20 echtcherbina Exp $
 */

package net.jxta.id;

import java.net.URL;

import java.net.MalformedURLException;

/**
 *  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
 *
 *  @version     $Revision: 1.2 $
 *  @since JXTA 1.0
 **/
public abstract class ID implements Cloneable, 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.
     * This is a singleton within the scope of a VM.
     **/
    public static final ID nullID = new NullID();

        
    /**
     *  Constructor for IDs.
     **/
    protected ID() {
    }
    
    /**
     *  Returns a clone of this object. All sub-classes of ID should be immutable
     *  but we have no way to enforce it. So, let subclasses override clone with
     *  a trivial method. Here, do the standard thing (which is correct for an
     *  abstract class), so that subclasses may call super.clone() in case their
     *  clone method is NOT trivial.
     *
     *  <p/>NOTE: We DO NOT throw CloneNotSupportedException; all IDs MUST be
     *  clonable by API definition.
     *
     *  @since JXTA 1.0
     *
     *  @return the cloned object
     **/
    public Object clone() {
        try {
            return super.clone();
        } catch (CloneNotSupportedException impossible) {
            return null;
        }
    }
    
    /**
     *  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 URL Objects via {@link #getURL() getURL}.
     *  The default implementation is the toString representation of the URL
     *  representation.
     *
     *  @since JXTA 1.0
     *
     *  @return	String containing the URI
     *
     **/
    public String toString( ) {
        return getURL().toString();
    }
    
    /**
     *
     *  Returns a string identifier which indicates which ID format is
     *  used by this ID instance.
     *
     *  @since JXTA 1.0
     *
     *  @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() 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>.
     *
     *  @since JXTA 1.0
     *
     *  @return	Object which can provide canonical representations of the ID.
     **/
    public abstract Object getUniqueValue();
    
    /**
     *  Returns a URI (URL in Java nomenclature) representation of the ID.
     * {@link java.net.URL URLs} 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 URLs containing JXTA IDs.
     *
     *  @see java.net.URL
     *  @see net.jxta.id.IDFactory#fromURL( java.net.URL )
     *  @since JXTA 1.0
     *
     *  @return	URL Object containing the URI
     **/
    public abstract URL getURL( );
}

class NullID extends ID {
    final static String JXTAFormat = "jxta";

    final static String UNIQUEVALUE = "Null";
        
    public Object clone() {
        return this;  // null is only itself.
    }
        
    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 this;
    }
    
    public URL getURL() {
        String urlText = URNNamespace + ":" + getUniqueValue();
        
        try {
            return new URL( URIEncodingName, "", urlText );
        }
        catch( MalformedURLException caught ) {
            throw new IllegalStateException( "Environment incorrectly intialized." );
        }
    }
    public String getIDFormat() {
        return JXTAFormat;
    }
    
    public Object getUniqueValue() {
        return getIDFormat() + "-" + UNIQUEVALUE;
    }
}