messageencoding.java

开放源码的smpp协议开发包

/*
 * Java SMPP API Copyright (C) 1998 - 2002 by Oran Kelly
 * 
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 * 
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 * 
 * A copy of the LGPL can be viewed at http://www.gnu.org/copyleft/lesser.html
 * Java SMPP API author: [e-mail] Java SMPP API Homepage:
 * http://smppapi.sourceforge.net/ $Id: MessageEncoding.java,v 1.4 2004/12/03
 * 17:49:47 orank Exp $
 */

package ie.omk.smpp.util;

import java.util.Hashtable;

public abstract class MessageEncoding {
    private static Hashtable dcMapping = new Hashtable();

    private int dataCoding = -1;

    protected MessageEncoding(int dataCoding) {
        this.dataCoding = dataCoding;
        dcMapping.put(new Integer(dataCoding), this);
    }

    /**
     * Get the correct data_coding value for this message encoding type.
     */
    public final int getDataCoding() {
        return (dataCoding);
    }

    /**
     * Get the MessageEncoding handler for data coding <i>dcs </i>.
     * 
     * @param dcs
     *            The data coding value to match.
     * @return The message encoding type registered, or null if none.
     */
    public static final MessageEncoding getEncoding(int dcs) {
        return ((MessageEncoding) dcMapping.get(new Integer(dcs)));
    }

    /**
     * Get the number of bits each encoded message byte represents. This method
     * will almost always return 8. The only known situation at this time where
     * the value should be different is in
     * {@link ie.omk.smpp.util.DefaultAlphabetEncoding}. The reason is that,
     * although the <code>DefaultAlphabetEncoding</code> will generate encoded
     * message byte arrays with one character in each byte location, in reality
     * each byte actually represents only 7-bits. When the message is re-encoded
     * at the SMSC, it will be compressed. This is how the GSM default alphabet
     * can fit 160 characters into a 140-byte payload. Most SMSCs, however,
     * accept the message in its uncompressed form.
     * <p>
     * It is not correct to return a value of 16 from an AlphabetEncoding which
     * encodes characters in 2 or more bytes. The reason that, although a
     * character is encoding as 2 bytes, in the <i>encoded form each byte
     * location still represents 8 bits </i>. This is an important distinction.
     * </p>
     */
    public int getEncodingLength() {
        return (8);
    }
}