bitmaskencoder.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: BitmaskEncoder.java,v 1.3 2005/05/09 21:04:51 orank Exp $
 */
package ie.omk.smpp.message.tlv;

import java.util.BitSet;

/**
 * Encoder for bit mask value types. This class encodes and decodes
 * {@link java.util.BitSet}objects to and from byte arrays.
 * 
 * @see java.util.BitSet
 */
public class BitmaskEncoder implements Encoder {

    /**
     * The BitmaskEncoder singleton.
     */
    private static final BitmaskEncoder instance = new BitmaskEncoder();

    /**
     * Create a new BitmaskEncoder. This is a singleton pattern, only one will
     * ever be created.
     */
    private BitmaskEncoder() {
    }

    /**
     * Get the singleton BitmaskEncoder instance.
     * 
     * @return The singleton BitmaskEncoder instance.
     */
    public static final BitmaskEncoder getInstance() {
        return (instance);
    }

    public void writeTo(Tag tag, Object value, byte[] b, int offset)
            throws ArrayIndexOutOfBoundsException {
        try {
            BitSet bs = (BitSet) value;
            int l = tag.getLength();

            for (int i = 0; i < l; i++) {
                b[offset + i] = 0;

                for (int j = 0; j < 8; j++) {
                    if (bs.get((i * 8) + j))
                        b[offset + i] |= (byte) (1 << j);
                }
            }
        } catch (ClassCastException x) {
            throw new BadValueTypeException("Value must be of type "
                    + "java.util.BitSet");
        }
    }

    public Object readFrom(Tag tag, byte[] b, int offset, int length)
            throws ArrayIndexOutOfBoundsException {
        BitSet bs = new BitSet();

        for (int i = 0; i < length; i++) {
            for (int j = 0; j < 8; j++) {
                if ((b[offset + i] & (byte) (1 << j)) > 0)
                    bs.set((i * 8) + j);
            }
        }

        return (bs);
    }

    public int getValueLength(Tag tag, Object value) {
        return (tag.getLength());
    }
}