    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;
    025import java.util.Objects;
    026
    027import org.apache.commons.codec.binary.BaseNCodec.Context;
    028
    029/**
    030 * Abstract superclass for Base-N output streams.
    031 * <p>
    032 * To write the EOF marker without closing the stream, call {@link #eof()} or use an <a
    033 * href="https://commons.apache.org/proper/commons-io/">Apache Commons IO</a> <a href=
    034 * "https://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/output/CloseShieldOutputStream.html"
    035 * >CloseShieldOutputStream</a>.
    036 * </p>
    037 *
    038 * @since 1.5
    039 */
    040public class BaseNCodecOutputStream extends FilterOutputStream {
    041
    042    private final boolean doEncode;
    043
    044    private final BaseNCodec baseNCodec;
    045
    046    private final byte[] singleByte = new byte[1];
    047
    048    private final Context context = new Context();
    049
    050    /**
    051     * TODO should this be protected?
    052     *
    053     * @param output the underlying output or null.
    054     * @param basedCodec a BaseNCodec.
    055     * @param doEncode true to encode, false to decode, TODO should be an enum?
    056     */
    057    public BaseNCodecOutputStream(final OutputStream output, final BaseNCodec basedCodec, final boolean doEncode) {
    058        super(output);
    059        this.baseNCodec = basedCodec;
    060        this.doEncode = doEncode;
    061    }
    062
    063    /**
    064     * Writes the specified {@code byte} to this output stream.
    065     *
    066     * @param i
    067     *            source byte
    068     * @throws IOException
    069     *             if an I/O error occurs.
    070     */
    071    @Override
    072    public void write(final int i) throws IOException {
    073        singleByte[0] = (byte) i;
    074        write(singleByte, 0, 1);
    075    }
    076
    077    /**
    078     * Writes {@code len} bytes from the specified {@code b} array starting at {@code offset} to this
    079     * output stream.
    080     *
    081     * @param array
    082     *            source byte array
    083     * @param offset
    084     *            where to start reading the bytes
    085     * @param len
    086     *            maximum number of bytes to write
    087     *
    088     * @throws IOException
    089     *             if an I/O error occurs.
    090     * @throws NullPointerException
    091     *             if the byte array parameter is null
    092     * @throws IndexOutOfBoundsException
    093     *             if offset, len or buffer size are invalid
    094     */
    095    @Override
    096    public void write(final byte array[], final int offset, final int len) throws IOException {
    097        Objects.requireNonNull(array, "array");
    098        if (offset < 0 || len < 0) {
    099            throw new IndexOutOfBoundsException();
    100        } else if (offset > array.length || offset + len > array.length) {
    101            throw new IndexOutOfBoundsException();
    102        } else if (len > 0) {
    103            if (doEncode) {
    104                baseNCodec.encode(array, offset, len, context);
    105            } else {
    106                baseNCodec.decode(array, offset, len, context);
    107            }
    108            flush(false);
    109        }
    110    }
    111
    112    /**
    113     * Flushes this output stream and forces any buffered output bytes to be written out to the stream. If propagate is
    114     * true, the wrapped stream will also be flushed.
    115     *
    116     * @param propagate
    117     *            boolean flag to indicate whether the wrapped OutputStream should also be flushed.
    118     * @throws IOException
    119     *             if an I/O error occurs.
    120     */
    121    private void flush(final boolean propagate) throws IOException {
    122        final int avail = baseNCodec.available(context);
    123        if (avail > 0) {
    124            final byte[] buf = new byte[avail];
    125            final int c = baseNCodec.readResults(buf, 0, avail, context);
    126            if (c > 0) {
    127                out.write(buf, 0, c);
    128            }
    129        }
    130        if (propagate) {
    131            out.flush();
    132        }
    133    }
    134
    135    /**
    136     * Flushes this output stream and forces any buffered output bytes to be written out to the stream.
    137     *
    138     * @throws IOException
    139     *             if an I/O error occurs.
    140     */
    141    @Override
    142    public void flush() throws IOException {
    143        flush(true);
    144    }
    145
    146    /**
    147     * Closes this output stream and releases any system resources associated with the stream.
    148     * <p>
    149     * To write the EOF marker without closing the stream, call {@link #eof()} or use an
    150     * <a href="https://commons.apache.org/proper/commons-io/">Apache Commons IO</a> <a href=
    151     * "https://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/output/CloseShieldOutputStream.html"
    152     * >CloseShieldOutputStream</a>.
    153     * </p>
    154     *
    155     * @throws IOException
    156     *             if an I/O error occurs.
    157     */
    158    @Override
    159    public void close() throws IOException {
    160        eof();
    161        flush();
    162        out.close();
    163    }
    164
    165    /**
    166     * Writes EOF.
    167     *
    168     * @throws IOException
    169     *             if an I/O error occurs.
    170     * @since 1.11
    171     */
    172    public void eof() throws IOException {
    173        // Notify encoder of EOF (-1).
    174        if (doEncode) {
    175            baseNCodec.encode(singleByte, 0, EOF, context);
    176        } else {
    177            baseNCodec.decode(singleByte, 0, EOF, context);
    178        }
    179    }
    180
    181}