    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.codec.binary;
    019
    020import static org.apache.commons.codec.binary.BaseNCodec.EOF;
    021
    022import java.io.FilterOutputStream;
    023import java.io.IOException;
    024import java.io.OutputStream;
    025
    026import org.apache.commons.codec.binary.BaseNCodec.Context;
    027
    028/**
    029 * Abstract superclass for Base-N output streams.
    030 *
    031 * @since 1.5
    032 * @version $Id: BaseNCodecOutputStream.java 1544347 2013-11-21 22:30:31Z ggregory $
    033 */
    034public class BaseNCodecOutputStream extends FilterOutputStream {
    035
    036    private final boolean doEncode;
    037
    038    private final BaseNCodec baseNCodec;
    039
    040    private final byte[] singleByte = new byte[1];
    041
    042    private final Context context = new Context();
    043
    044    // TODO should this be protected?
    045    public BaseNCodecOutputStream(final OutputStream out, final BaseNCodec basedCodec, final boolean doEncode) {
    046        super(out);
    047        this.baseNCodec = basedCodec;
    048        this.doEncode = doEncode;
    049    }
    050
    051    /**
    052     * Writes the specified <code>byte</code> to this output stream.
    053     *
    054     * @param i
    055     *            source byte
    056     * @throws IOException
    057     *             if an I/O error occurs.
    058     */
    059    @Override
    060    public void write(final int i) throws IOException {
    061        singleByte[0] = (byte) i;
    062        write(singleByte, 0, 1);
    063    }
    064
    065    /**
    066     * Writes <code>len</code> bytes from the specified <code>b</code> array starting at <code>offset</code> to this
    067     * output stream.
    068     *
    069     * @param b
    070     *            source byte array
    071     * @param offset
    072     *            where to start reading the bytes
    073     * @param len
    074     *            maximum number of bytes to write
    075     *
    076     * @throws IOException
    077     *             if an I/O error occurs.
    078     * @throws NullPointerException
    079     *             if the byte array parameter is null
    080     * @throws IndexOutOfBoundsException
    081     *             if offset, len or buffer size are invalid
    082     */
    083    @Override
    084    public void write(final byte b[], final int offset, final int len) throws IOException {
    085        if (b == null) {
    086            throw new NullPointerException();
    087        } else if (offset < 0 || len < 0) {
    088            throw new IndexOutOfBoundsException();
    089        } else if (offset > b.length || offset + len > b.length) {
    090            throw new IndexOutOfBoundsException();
    091        } else if (len > 0) {
    092            if (doEncode) {
    093                baseNCodec.encode(b, offset, len, context);
    094            } else {
    095                baseNCodec.decode(b, offset, len, context);
    096            }
    097            flush(false);
    098        }
    099    }
    100
    101    /**
    102     * Flushes this output stream and forces any buffered output bytes to be written out to the stream. If propagate is
    103     * true, the wrapped stream will also be flushed.
    104     *
    105     * @param propagate
    106     *            boolean flag to indicate whether the wrapped OutputStream should also be flushed.
    107     * @throws IOException
    108     *             if an I/O error occurs.
    109     */
    110    private void flush(final boolean propagate) throws IOException {
    111        final int avail = baseNCodec.available(context);
    112        if (avail > 0) {
    113            final byte[] buf = new byte[avail];
    114            final int c = baseNCodec.readResults(buf, 0, avail, context);
    115            if (c > 0) {
    116                out.write(buf, 0, c);
    117            }
    118        }
    119        if (propagate) {
    120            out.flush();
    121        }
    122    }
    123
    124    /**
    125     * Flushes this output stream and forces any buffered output bytes to be written out to the stream.
    126     *
    127     * @throws IOException
    128     *             if an I/O error occurs.
    129     */
    130    @Override
    131    public void flush() throws IOException {
    132        flush(true);
    133    }
    134
    135    /**
    136     * Closes this output stream and releases any system resources associated with the stream.
    137     *
    138     * @throws IOException
    139     *             if an I/O error occurs.
    140     */
    141    @Override
    142    public void close() throws IOException {
    143        // Notify encoder of EOF (-1).
    144        if (doEncode) {
    145            baseNCodec.encode(singleByte, 0, EOF, context);
    146        } else {
    147            baseNCodec.decode(singleByte, 0, EOF, context);
    148        }
    149        flush();
    150        out.close();
    151    }
    152
    153}