messageelement.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

/************************************************************************
 *
 * $Id: MessageElement.java,v 1.2 2002/03/04 20:18:38 echtcherbina Exp $
 *
 * 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.
 *********************************************************************************/

package net.jxta.endpoint;

import java.io.InputStream;
import net.jxta.document.MimeMediaType;
import java.io.Serializable;

/**
 * This abstract class defines the Message Element. 
 *
 * @see net.jxta.endpoint.Message
 */
abstract public class MessageElement {
    
    /**
     * Returns the offset into the array returned by getBytes()
     * of where data use by this element starts.
     *
     * @return int the offset.
     */
    abstract public int getOffset();

    /**
     *   Returns the number of bytes used in the array
     *   returned by getBytes().  This may or may not be the
     *   entire length of the array returned by getBytes().
     *   <P>
     *   post:<br>
     *   0 <= getLength() <= getBytes().length
     *   <p>
     *   @return int the number of bytes of the element data.
     *
     *  @since JXTA 1.0
     **/
    abstract public int getLength();
    
    
    /**
     *   Returns the byte array which contains the element data.
     *   The portion of the array
     *   which is used as the element data starts at getOffset()
     *   and continues up to but not including the byte at 
     *   getOffset()+getLength().
     *   <P>
     *   The byte array returned is not a copy of the element
     *   content.  
     *
     *   @return byte[] Contents of message element.
     */
    abstract public byte[] getBytesOffset();
    
    
    /**
     *   Returns a stream containing the element data.  This
     *   stream contains the segment of bytes in the array
     *   returned by getBytes() from getOffset() to getOffset() + getLength()-1;
     *
     *   @return InputStream of the stream containing element data.
     *
     *  @since JXTA 1.0
     **/
    abstract public InputStream getStream();
    
    /**
     *  Returns the name of the MessageElement.
     *
     *  @return String containing the name of the MessageElement.
     *
     *  @since JXTA 1.0
     **/    
    abstract public String getName();
    
    /**
     *  Returns the type of the MessageElement.
     *
     *  @return MimeMediaType containing a copy of the type of the element.
     *   Will return "Application/Octet-Stream" if no type was originally
     *   specified.
     *
     *  @since JXTA 1.0
     **/
    abstract public MimeMediaType getType();
        
    /**
     *  make a clone of this element. Since element are immutable, this
     *  returns the same object.
     *
     *  XXX 20010615    [e-mail]    Since the elements make an
     *  effort to *not* copy the source data would it make sense to have
     *  clone return a true clone which has no external dependancies? The
     *  other alternative is to add an intern() method which resolves
     *  external dependencies by copying the data.
     *
     *  @return Object a copy of the MessageElement.
     *
     *  @since JXTA 1.0
     **/
    abstract public Object clone( );
    
    /**
     *  Compare this MessageElement against another.  They
     *  are equal if the namespace, name, type, data are equal.
     *
     *  @param target The  to compare against.
     *  @return boolean true if the elements are identical.
     *
     *  @since JXTA 1.0
     **/
    abstract public boolean equals( Object target );

    /**
     * Parse a name in to its two colon separated components.
     * The namespace is to the left of the colon.  The simple
     * name is to the right of the colon.  If no colon is present
     * The namespace is the empty namespace, and the simple name
     * is the same as the name arg.  
     * <P>
     * parseName returns an arrary of String defined as follow:
     * <p>
     * String[0] contains the namespace.<BR>
     * String[1] contains the simple name.
     * <p>
     * @param name is the name to parse.
     * @return String[] the array of String containing the name space and the
     * simple name.
     */
    static public String[] parseName(String name)
    {
        String[] names = new String[2];
        
        int i = name.indexOf(':');
        if (i == -1) {
            names[0] = "";
            names[1] = name;
        } else {
            names[0] = name.substring(0, i);
            names[1] = name.substring(i+1);
        }
        
        return names;
    }
}