Java ByteBuffer wrap as ReadableByteChannel

import java.io.IOException;
import java.nio.ByteBuffer;

import java.nio.channels.ClosedChannelException;
import java.nio.channels.ReadableByteChannel;

public class Main {
    public static ReadableByteChannel asReadableByteChannel(
            final ByteBuffer buffer) {

        return new ReadableByteChannel() {

            private boolean open = true;

            public int read(ByteBuffer dst) throws IOException {
                if (open == false) {
                    throw new ClosedChannelException();
                }//from w w  w. j a  va2 s.c  o m

                final int p = buffer.position();
                final int l = buffer.limit();
                final int r = dst.remaining();

                buffer.limit(p + r);

                dst.put(buffer);

                buffer.limit(l);

                return r;
            }

            public void close() throws IOException {
                open = false;
            }

            public boolean isOpen() {
                return open;
            }

        };
    }
}
/**
 * Copyright (C) 2007 Sly Technologies, Inc. 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */