    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 */
    017package org.apache.commons.io;
    018
    019import static org.apache.commons.io.IOUtils.EOF;
    020
    021import java.io.ByteArrayInputStream;
    022import java.io.IOException;
    023import java.io.InputStream;
    024import java.io.InputStreamReader;
    025import java.io.OutputStream;
    026import java.io.OutputStreamWriter;
    027import java.io.Reader;
    028import java.io.StringReader;
    029import java.io.Writer;
    030import java.nio.charset.Charset;
    031
    032/**
    033 * This class provides static utility methods for buffered
    034 * copying between sources ({@code InputStream}, {@code Reader},
    035 * {@code String} and {@code byte[]}) and destinations
    036 * ({@code OutputStream}, {@code Writer}, {@code String} and
    037 * {@code byte[]}).
    038 * <p>
    039 * Unless otherwise noted, these {@code copy} methods do <em>not</em>
    040 * flush or close the streams. Often doing so would require making non-portable
    041 * assumptions about the streams' origin and further use. This means that both
    042 * streams' {@code close()} methods must be called after copying. if one
    043 * omits this step, then the stream resources (sockets, file descriptors) are
    044 * released when the associated Stream is garbage-collected. It is not a good
    045 * idea to rely on this mechanism. For a good overview of the distinction
    046 * between "memory management" and "resource management", see
    047 * <a href="http://www.unixreview.com/articles/1998/9804/9804ja/ja.htm">this
    048 * UnixReview article</a>.
    049 * <p>
    050 * For byte-to-char methods, a {@code copy} variant allows the encoding
    051 * to be selected (otherwise the platform default is used). We would like to
    052 * encourage you to always specify the encoding because relying on the platform
    053 * default can lead to unexpected results.
    054 * <p>
    055 * We don't provide special variants for the {@code copy} methods that
    056 * let you specify the buffer size because in modern VMs the impact on speed
    057 * seems to be minimal. We're using a default buffer size of 4 KB.
    058 * <p>
    059 * The {@code copy} methods use an internal buffer when copying. It is
    060 * therefore advisable <em>not</em> to deliberately wrap the stream arguments
    061 * to the {@code copy} methods in {@code Buffered*} streams. For
    062 * example, don't do the following:
    063 * <pre>
    064 *  copy( new BufferedInputStream( in ), new BufferedOutputStream( out ) );
    065 *  </pre>
    066 * The rationale is as follows:
    067 * <p>
    068 * Imagine that an InputStream's read() is a very expensive operation, which
    069 * would usually suggest wrapping in a BufferedInputStream. The
    070 * BufferedInputStream works by issuing infrequent
    071 * {@link java.io.InputStream#read(byte[] b, int off, int len)} requests on the
    072 * underlying InputStream, to fill an internal buffer, from which further
    073 * {@code read} requests can inexpensively get their data (until the buffer
    074 * runs out).
    075 * <p>
    076 * However, the {@code copy} methods do the same thing, keeping an
    077 * internal buffer, populated by
    078 * {@link InputStream#read(byte[] b, int off, int len)} requests. Having two
    079 * buffers (or three if the destination stream is also buffered) is pointless,
    080 * and the unnecessary buffer management hurts performance slightly (about 3%,
    081 * according to some simple experiments).
    082 * <p>
    083 * Behold, intrepid explorers; a map of this class:
    084 * <pre>
    085 *       Method      Input               Output          Dependency
    086 *       ------      -----               ------          -------
    087 * 1     copy        InputStream         OutputStream    (primitive)
    088 * 2     copy        Reader              Writer          (primitive)
    089 *
    090 * 3     copy        InputStream         Writer          2
    091 *
    092 * 4     copy        Reader              OutputStream    2
    093 *
    094 * 5     copy        String              OutputStream    2
    095 * 6     copy        String              Writer          (trivial)
    096 *
    097 * 7     copy        byte[]              Writer          3
    098 * 8     copy        byte[]              OutputStream    (trivial)
    099 * </pre>
    100 * <p>
    101 * Note that only the first two methods shuffle bytes; the rest use these
    102 * two, or (if possible) copy using native Java copy methods. As there are
    103 * method variants to specify the encoding, each row may
    104 * correspond to up to 2 methods.
    105 * <p>
    106 * Origin of code: Excalibur.
    107 *
    108 * @deprecated Use IOUtils. Will be removed in 3.0.
    109 *  Methods renamed to IOUtils.write() or IOUtils.copy().
    110 *  Null handling behavior changed in IOUtils (null data does not
    111 *  throw NullPointerException).
    112 */
    113@Deprecated
    114public class CopyUtils {
    115
    116    /**
    117     * Instances should NOT be constructed in standard programming.
    118     */
    119    public CopyUtils() { }
    120
    121    /**
    122     * Copies bytes from a {@code byte[]} to an {@code OutputStream}.
    123     * @param input the byte array to read from
    124     * @param output the {@code OutputStream} to write to
    125     * @throws IOException In case of an I/O problem
    126     */
    127    public static void copy(final byte[] input, final OutputStream output) throws IOException {
    128        output.write(input);
    129    }
    130
    131    /**
    132     * Copies and convert bytes from a {@code byte[]} to chars on a
    133     * {@code Writer}.
    134     * The platform's default encoding is used for the byte-to-char conversion.
    135     * @param input the byte array to read from
    136     * @param output the {@code Writer} to write to
    137     * @throws IOException In case of an I/O problem
    138     * @deprecated 2.5 use {@link #copy(byte[], Writer, String)} instead
    139     */
    140    @Deprecated
    141    public static void copy(final byte[] input, final Writer output) throws IOException {
    142        final ByteArrayInputStream inputStream = new ByteArrayInputStream(input);
    143        copy(inputStream, output);
    144    }
    145
    146    /**
    147     * Copies and convert bytes from a {@code byte[]} to chars on a
    148     * {@code Writer}, using the specified encoding.
    149     * @param input the byte array to read from
    150     * @param output the {@code Writer} to write to
    151     * @param encoding The name of a supported character encoding. See the
    152     * <a href="http://www.iana.org/assignments/character-sets">IANA
    153     * Charset Registry</a> for a list of valid encoding types.
    154     * @throws IOException In case of an I/O problem
    155     */
    156    public static void copy(final byte[] input, final Writer output, final String encoding) throws IOException {
    157        final ByteArrayInputStream inputStream = new ByteArrayInputStream(input);
    158        copy(inputStream, output, encoding);
    159    }
    160
    161    /**
    162     * Copies bytes from an {@code InputStream} to an
    163     * {@code OutputStream}.
    164     * @param input the {@code InputStream} to read from
    165     * @param output the {@code OutputStream} to write to
    166     * @return the number of bytes copied
    167     * @throws IOException In case of an I/O problem
    168     */
    169    public static int copy(final InputStream input, final OutputStream output) throws IOException {
    170        final byte[] buffer = IOUtils.byteArray();
    171        int count = 0;
    172        int n = 0;
    173        while (EOF != (n = input.read(buffer))) {
    174            output.write(buffer, 0, n);
    175            count += n;
    176        }
    177        return count;
    178    }
    179
    180    // ----------------------------------------------------------------
    181    // Reader -> Writer
    182    // ----------------------------------------------------------------
    183
    184    /**
    185     * Copies chars from a {@code Reader} to a {@code Writer}.
    186     * @param input the {@code Reader} to read from
    187     * @param output the {@code Writer} to write to
    188     * @return the number of characters copied
    189     * @throws IOException In case of an I/O problem
    190     */
    191    public static int copy(
    192            final Reader input,
    193            final Writer output)
    194                throws IOException {
    195        final char[] buffer = IOUtils.getCharArray();
    196        int count = 0;
    197        int n = 0;
    198        while (EOF != (n = input.read(buffer))) {
    199            output.write(buffer, 0, n);
    200            count += n;
    201        }
    202        return count;
    203    }
    204
    205    // ----------------------------------------------------------------
    206    // InputStream -> Writer
    207    // ----------------------------------------------------------------
    208
    209    /**
    210     * Copies and convert bytes from an {@code InputStream} to chars on a
    211     * {@code Writer}.
    212     * The platform's default encoding is used for the byte-to-char conversion.
    213     * @param input the {@code InputStream} to read from
    214     * @param output the {@code Writer} to write to
    215     * @throws IOException In case of an I/O problem
    216     * @deprecated 2.5 use {@link #copy(InputStream, Writer, String)} instead
    217     */
    218    @Deprecated
    219    public static void copy(
    220            final InputStream input,
    221            final Writer output)
    222                throws IOException {
    223        // make explicit the dependency on the default encoding
    224        final InputStreamReader in = new InputStreamReader(input, Charset.defaultCharset());
    225        copy(in, output);
    226    }
    227
    228    /**
    229     * Copies and convert bytes from an {@code InputStream} to chars on a
    230     * {@code Writer}, using the specified encoding.
    231     * @param input the {@code InputStream} to read from
    232     * @param output the {@code Writer} to write to
    233     * @param encoding The name of a supported character encoding. See the
    234     * <a href="http://www.iana.org/assignments/character-sets">IANA
    235     * Charset Registry</a> for a list of valid encoding types.
    236     * @throws IOException In case of an I/O problem
    237     */
    238    public static void copy(
    239            final InputStream input,
    240            final Writer output,
    241            final String encoding)
    242                throws IOException {
    243        final InputStreamReader in = new InputStreamReader(input, encoding);
    244        copy(in, output);
    245    }
    246
    247
    248    // ----------------------------------------------------------------
    249    // Reader -> OutputStream
    250    // ----------------------------------------------------------------
    251
    252    /**
    253     * Serialize chars from a {@code Reader} to bytes on an
    254     * {@code OutputStream}, and flush the {@code OutputStream}.
    255     * Uses the default platform encoding.
    256     * @param input the {@code Reader} to read from
    257     * @param output the {@code OutputStream} to write to
    258     * @throws IOException In case of an I/O problem
    259     * @deprecated 2.5 use {@link #copy(Reader, OutputStream, String)} instead
    260     */
    261    @Deprecated
    262    public static void copy(
    263            final Reader input,
    264            final OutputStream output)
    265                throws IOException {
    266        // make explicit the dependency on the default encoding
    267        final OutputStreamWriter out = new OutputStreamWriter(output, Charset.defaultCharset());
    268        copy(input, out);
    269        // XXX Unless anyone is planning on rewriting OutputStreamWriter, we
    270        // have to flush here.
    271        out.flush();
    272    }
    273
    274    /**
    275     * Serialize chars from a {@code Reader} to bytes on an
    276     * {@code OutputStream}, and flush the {@code OutputStream}.
    277     * @param input the {@code Reader} to read from
    278     * @param output the {@code OutputStream} to write to
    279     * @param encoding The name of a supported character encoding. See the
    280     * <a href="http://www.iana.org/assignments/character-sets">IANA
    281     * Charset Registry</a> for a list of valid encoding types.
    282     * @throws IOException In case of an I/O problem
    283     * @since 2.5
    284     */
    285    public static void copy(
    286            final Reader input,
    287            final OutputStream output,
    288            final String encoding)
    289                throws IOException {
    290        final OutputStreamWriter out = new OutputStreamWriter(output, encoding);
    291        copy(input, out);
    292        // XXX Unless anyone is planning on rewriting OutputStreamWriter, we
    293        // have to flush here.
    294        out.flush();
    295    }
    296
    297    // ----------------------------------------------------------------
    298    // String -> OutputStream
    299    // ----------------------------------------------------------------
    300
    301    /**
    302     * Serialize chars from a {@code String} to bytes on an
    303     * {@code OutputStream}, and
    304     * flush the {@code OutputStream}.
    305     * Uses the platform default encoding.
    306     * @param input the {@code String} to read from
    307     * @param output the {@code OutputStream} to write to
    308     * @throws IOException In case of an I/O problem
    309     * @deprecated 2.5 use {@link #copy(String, OutputStream, String)} instead
    310     */
    311    @Deprecated
    312    public static void copy(
    313            final String input,
    314            final OutputStream output)
    315                throws IOException {
    316        final StringReader in = new StringReader(input);
    317        // make explicit the dependency on the default encoding
    318        final OutputStreamWriter out = new OutputStreamWriter(output, Charset.defaultCharset());
    319        copy(in, out);
    320        // XXX Unless anyone is planning on rewriting OutputStreamWriter, we
    321        // have to flush here.
    322        out.flush();
    323    }
    324
    325    /**
    326     * Serialize chars from a {@code String} to bytes on an
    327     * {@code OutputStream}, and
    328     * flush the {@code OutputStream}.
    329     * @param input the {@code String} to read from
    330     * @param output the {@code OutputStream} to write to
    331     * @param encoding The name of a supported character encoding. See the
    332     * <a href="http://www.iana.org/assignments/character-sets">IANA
    333     * Charset Registry</a> for a list of valid encoding types.
    334     * @throws IOException In case of an I/O problem
    335     * @since 2.5
    336     */
    337    public static void copy(
    338            final String input,
    339            final OutputStream output,
    340            final String encoding)
    341                throws IOException {
    342        final StringReader in = new StringReader(input);
    343        final OutputStreamWriter out = new OutputStreamWriter(output, encoding);
    344        copy(in, out);
    345        // XXX Unless anyone is planning on rewriting OutputStreamWriter, we
    346        // have to flush here.
    347        out.flush();
    348    }
    349
    350    // ----------------------------------------------------------------
    351    // String -> Writer
    352    // ----------------------------------------------------------------
    353
    354    /**
    355     * Copies chars from a {@code String} to a {@code Writer}.
    356     * @param input the {@code String} to read from
    357     * @param output the {@code Writer} to write to
    358     * @throws IOException In case of an I/O problem
    359     */
    360    public static void copy(final String input, final Writer output)
    361                throws IOException {
    362        output.write(input);
    363    }
    364
    365}