stringmessageelement.java

JXTA&#8482 is a set of open, generalized peer-to-peer (P2P) protocols that allow any networked devi

/*
 * Copyright (c) 2001-2007 Sun Microsystems, Inc.  All rights reserved.
 *  
 *  The Sun Project JXTA(TM) Software License
 *  
 *  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 Sun Microsystems, Inc. for JXTA(TM) technology." 
 *     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, 
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 *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, 
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 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 
 *  EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *  
 *  JXTA is a registered trademark of Sun Microsystems, Inc. in the United 
 *  States and other countries.
 *  
 *  Please see the license information page at :
 *  <http://www.jxta.org/project/www/license.html> for instructions on use of 
 *  the license in source files.
 *  
 *  ====================================================================
 *  
 *  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 net.jxta.document.MimeMediaType;
import net.jxta.logging.Logging;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.Reader;
import java.io.StringReader;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.lang.ref.SoftReference;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CoderResult;
import java.nio.charset.CodingErrorAction;
import java.util.logging.Level;
import java.util.logging.Logger;


/**
 * A Message Element using character strings for the element data.
 */
public class StringMessageElement extends TextMessageElement {

    /**
     * Logger
     */
    private final static transient Logger LOG = Logger.getLogger(StringMessageElement.class.getName());

    /**
     * The MIME media type we will be use for encoding {@code String}s when no
     * encoding is specified.
     */
    private static final MimeMediaType DEFAULT_TEXT_ENCODING = new MimeMediaType(MimeMediaType.TEXT_DEFAULTENCODING, "charset=\"" + Charset.defaultCharset().name() + "\"", true).intern();

    /**
     * The data for this Message Element.
     */
    protected String data;

    /**
     * Returns an appropriate mime type for the given encoding name. The
     * mimetype will contain the canonical name of the encoding.
     *
     * @param encoding name of the desired encoding.
     * @return the mime type.
     * @throws java.io.UnsupportedEncodingException
     *          if the mime is unsupported
     */
    private static MimeMediaType makeMimeType(String encoding) throws UnsupportedEncodingException {
        InputStreamReader getEncoding = new InputStreamReader(new ByteArrayInputStream(new byte[0]), encoding);

        String canonicalName = getEncoding.getEncoding();

        return new MimeMediaType(MimeMediaType.TEXT_DEFAULTENCODING, "charset=\"" + canonicalName + "\"", true).intern();
    }

    /**
     * Create a new Message Element from the provided String. The String will
     * be encoded for transmission using UTF-8.
     *
     * @param name  Name of the Element. May be the empty string ("") or null if
     *              the Element is not named.
     * @param value A String containing the contents of this element.
     * @param sig   Message digest/digital signature element. If no signature is
     *              to be specified, pass <code>null</code>.
     * @throws IllegalArgumentException if <code>value</code> is
     *                                  <code>null</code>.
     */
    public StringMessageElement(String name, String value, MessageElement sig) {
        super(name, MimeMediaType.TEXTUTF8, sig);

        if (null == value) {
            throw new IllegalArgumentException("value must be non-null");
        }

        data = value;
    }

    /**
     * Create a new Message Element from the provided String. The string will
     * be encoded for transmission using specified character encoding.
     *
     * @param name     Name of the MessageElement. May be the empty string ("") or
     *                 <code>null</code> if the MessageElement is not named.
     * @param value    A String containing the contents of this element.
     * @param encoding Name of the character encoding to use. If
     *                 <code>null</code> then the system default character encoding will be
     *                 used. (Using the system default character encoding should be used with
     *                 extreme caution).
     * @param sig      Message digest/digital signature element. If no signature is
     *                 to be specified, pass <code>null</code>.
     * @throws IllegalArgumentException     if <code>value</code> is
     *                                      <code>null</code>.
     * @throws UnsupportedEncodingException if the requested encoding is not
     *                                      supported.
     */
    public StringMessageElement(String name, String value, String encoding, MessageElement sig) throws UnsupportedEncodingException {
        super(name, (null == encoding) ? DEFAULT_TEXT_ENCODING : makeMimeType(encoding), sig);

        if (null == value) {
            throw new IllegalArgumentException("value must be non-null");
        }

        data = value;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean equals(Object target) {
        if (this == target) {
            return true;
        }

        if (target instanceof MessageElement) {
            if (!super.equals(target)) {
                return false;
            }

            if (target instanceof StringMessageElement) {
                StringMessageElement likeMe = (StringMessageElement) target;

                return data.equals(likeMe.data); // same chars?
            } else if (target instanceof TextMessageElement) {
                // have to do a slow char by char comparison. Still better than the stream since it saves encoding.
                // XXX 20020615 [e-mail] the performance of this could be much improved.

                TextMessageElement likeMe = (TextMessageElement) target;

                try {
                    Reader myReader = getReader();
                    Reader itsReader = likeMe.getReader();

                    int mine;
                    int its;

                    do {
                        mine = myReader.read();
                        its = itsReader.read();

                        if (mine != its) {
                            return false;
                        }       // content didn't match

                    } while ((-1 != mine) && (-1 != its));

                    return ((-1 == mine) && (-1 == its)); // end at the same time?
                } catch (IOException fatal) {
                    IllegalStateException failure = new IllegalStateException("MessageElements could not be compared.");

                    failure.initCause(fatal);
                    throw failure;
                }
            } else {
                // have to do a slow stream comparison.
                // XXX 20020615 [e-mail] the performance of this could be much improved.

                MessageElement likeMe = (MessageElement) target;

                try {
                    InputStream myStream = getStream();
                    InputStream itsStream = likeMe.getStream();

                    int mine;
                    int its;

                    do {
                        mine = myStream.read();
                        its = itsStream.read();

                        if (mine != its) {
                            return false;
                        }       // content didn't match

                    } while ((-1 != mine) && (-1 != its));

                    return ((-1 == mine) && (-1 == its)); // end at the same time?
                } catch (IOException fatal) {
                    IllegalStateException failure = new IllegalStateException("MessageElements could not be compared.");

                    failure.initCause(fatal);
                    throw failure;
                }
            }
        }

        return false; // not a new message element
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int hashCode() {
        int result = super.hashCode() * 6037 + // a prime
                data.hashCode();

        return result;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String toString() {
        return data;
    }

    /**
     * {@inheritDoc}