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