    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    package org.apache.commons.io;
    018
    019    import java.io.ByteArrayInputStream;
    020    import java.io.IOException;
    021    import java.io.InputStream;
    022    import java.io.InputStreamReader;
    023    import java.io.OutputStream;
    024    import java.io.OutputStreamWriter;
    025    import java.io.Reader;
    026    import java.io.StringReader;
    027    import java.io.Writer;
    028
    029    /**
    030     * This class provides static utility methods for buffered
    031     * copying between sources (<code>InputStream</code>, <code>Reader</code>,
    032     * <code>String</code> and <code>byte[]</code>) and destinations
    033     * (<code>OutputStream</code>, <code>Writer</code>, <code>String</code> and
    034     * <code>byte[]</code>).
    035     * <p>
    036     * Unless otherwise noted, these <code>copy</code> methods do <em>not</em>
    037     * flush or close the streams. Often doing so would require making non-portable
    038     * assumptions about the streams' origin and further use. This means that both
    039     * streams' <code>close()</code> methods must be called after copying. if one
    040     * omits this step, then the stream resources (sockets, file descriptors) are
    041     * released when the associated Stream is garbage-collected. It is not a good
    042     * idea to rely on this mechanism. For a good overview of the distinction
    043     * between "memory management" and "resource management", see
    044     * <a href="http://www.unixreview.com/articles/1998/9804/9804ja/ja.htm">this
    045     * UnixReview article</a>.
    046     * <p>
    047     * For byte-to-char methods, a <code>copy</code> variant allows the encoding
    048     * to be selected (otherwise the platform default is used). We would like to
    049     * encourage you to always specify the encoding because relying on the platform
    050     * default can lead to unexpected results.
    051     * <p
    052     * We don't provide special variants for the <code>copy</code> methods that
    053     * let you specify the buffer size because in modern VMs the impact on speed
    054     * seems to be minimal. We're using a default buffer size of 4 KB.
    055     * <p>
    056     * The <code>copy</code> methods use an internal buffer when copying. It is
    057     * therefore advisable <em>not</em> to deliberately wrap the stream arguments
    058     * to the <code>copy</code> methods in <code>Buffered*</code> streams. For
    059     * example, don't do the following:
    060     * <pre>
    061     *  copy( new BufferedInputStream( in ), new BufferedOutputStream( out ) );
    062     *  </pre>
    063     * The rationale is as follows:
    064     * <p>
    065     * Imagine that an InputStream's read() is a very expensive operation, which
    066     * would usually suggest wrapping in a BufferedInputStream. The
    067     * BufferedInputStream works by issuing infrequent
    068     * {@link java.io.InputStream#read(byte[] b, int off, int len)} requests on the
    069     * underlying InputStream, to fill an internal buffer, from which further
    070     * <code>read</code> requests can inexpensively get their data (until the buffer
    071     * runs out).
    072     * <p>
    073     * However, the <code>copy</code> methods do the same thing, keeping an
    074     * internal buffer, populated by
    075     * {@link InputStream#read(byte[] b, int off, int len)} requests. Having two
    076     * buffers (or three if the destination stream is also buffered) is pointless,
    077     * and the unnecessary buffer management hurts performance slightly (about 3%,
    078     * according to some simple experiments).
    079     * <p>
    080     * Behold, intrepid explorers; a map of this class:
    081     * <pre>
    082     *       Method      Input               Output          Dependency
    083     *       ------      -----               ------          -------
    084     * 1     copy        InputStream         OutputStream    (primitive)
    085     * 2     copy        Reader              Writer          (primitive)
    086     *
    087     * 3     copy        InputStream         Writer          2
    088     *
    089     * 4     copy        Reader              OutputStream    2
    090     *
    091     * 5     copy        String              OutputStream    2
    092     * 6     copy        String              Writer          (trivial)
    093     *
    094     * 7     copy        byte[]              Writer          3
    095     * 8     copy        byte[]              OutputStream    (trivial)
    096     * </pre>
    097     * <p>
    098     * Note that only the first two methods shuffle bytes; the rest use these
    099     * two, or (if possible) copy using native Java copy methods. As there are
    100     * method variants to specify the encoding, each row may
    101     * correspond to up to 2 methods.
    102     * <p>
    103     * Origin of code: Excalibur.
    104     *
    105     * @author Peter Donald
    106     * @author Jeff Turner
    107     * @author Matthew Hawthorne
    108     * @version $Id: CopyUtils.java 659817 2008-05-24 13:23:10Z niallp $
    109     * @deprecated Use IOUtils. Will be removed in 2.0.
    110     *  Methods renamed to IOUtils.write() or IOUtils.copy().
    111     *  Null handling behaviour changed in IOUtils (null data does not
    112     *  throw NullPointerException).
    113     */
    114    @Deprecated
    115    public class CopyUtils {
    116
    117        /**
    118         * The default size of the buffer.
    119         */
    120        private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;
    121
    122        /**
    123         * Instances should NOT be constructed in standard programming.
    124         */
    125        public CopyUtils() { }
    126
    127        // ----------------------------------------------------------------
    128        // byte[] -> OutputStream
    129        // ----------------------------------------------------------------
    130
    131        /**
    132         * Copy bytes from a <code>byte[]</code> to an <code>OutputStream</code>.
    133         * @param input the byte array to read from
    134         * @param output the <code>OutputStream</code> to write to
    135         * @throws IOException In case of an I/O problem
    136         */
    137        public static void copy(byte[] input, OutputStream output)
    138                throws IOException {
    139            output.write(input);
    140        }
    141
    142        // ----------------------------------------------------------------
    143        // byte[] -> Writer
    144        // ----------------------------------------------------------------
    145
    146        /**
    147         * Copy and convert bytes from a <code>byte[]</code> to chars on a
    148         * <code>Writer</code>.
    149         * The platform's default encoding is used for the byte-to-char conversion.
    150         * @param input the byte array to read from
    151         * @param output the <code>Writer</code> to write to
    152         * @throws IOException In case of an I/O problem
    153         */
    154        public static void copy(byte[] input, Writer output)
    155                throws IOException {
    156            ByteArrayInputStream in = new ByteArrayInputStream(input);
    157            copy(in, output);
    158        }
    159
    160
    161        /**
    162         * Copy and convert bytes from a <code>byte[]</code> to chars on a
    163         * <code>Writer</code>, using the specified encoding.
    164         * @param input the byte array to read from
    165         * @param output the <code>Writer</code> to write to
    166         * @param encoding The name of a supported character encoding. See the
    167         * <a href="http://www.iana.org/assignments/character-sets">IANA
    168         * Charset Registry</a> for a list of valid encoding types.
    169         * @throws IOException In case of an I/O problem
    170         */
    171        public static void copy(
    172                byte[] input,
    173                Writer output,
    174                String encoding)
    175                    throws IOException {
    176            ByteArrayInputStream in = new ByteArrayInputStream(input);
    177            copy(in, output, encoding);
    178        }
    179
    180
    181        // ----------------------------------------------------------------
    182        // Core copy methods
    183        // ----------------------------------------------------------------
    184
    185        /**
    186         * Copy bytes from an <code>InputStream</code> to an
    187         * <code>OutputStream</code>.
    188         * @param input the <code>InputStream</code> to read from
    189         * @param output the <code>OutputStream</code> to write to
    190         * @return the number of bytes copied
    191         * @throws IOException In case of an I/O problem
    192         */
    193        public static int copy(
    194                InputStream input,
    195                OutputStream output)
    196                    throws IOException {
    197            byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
    198            int count = 0;
    199            int n = 0;
    200            while (-1 != (n = input.read(buffer))) {
    201                output.write(buffer, 0, n);
    202                count += n;
    203            }
    204            return count;
    205        }
    206
    207        // ----------------------------------------------------------------
    208        // Reader -> Writer
    209        // ----------------------------------------------------------------
    210
    211        /**
    212         * Copy chars from a <code>Reader</code> to a <code>Writer</code>.
    213         * @param input the <code>Reader</code> to read from
    214         * @param output the <code>Writer</code> to write to
    215         * @return the number of characters copied
    216         * @throws IOException In case of an I/O problem
    217         */
    218        public static int copy(
    219                Reader input,
    220                Writer output)
    221                    throws IOException {
    222            char[] buffer = new char[DEFAULT_BUFFER_SIZE];
    223            int count = 0;
    224            int n = 0;
    225            while (-1 != (n = input.read(buffer))) {
    226                output.write(buffer, 0, n);
    227                count += n;
    228            }
    229            return count;
    230        }
    231
    232        // ----------------------------------------------------------------
    233        // InputStream -> Writer
    234        // ----------------------------------------------------------------
    235
    236        /**
    237         * Copy and convert bytes from an <code>InputStream</code> to chars on a
    238         * <code>Writer</code>.
    239         * The platform's default encoding is used for the byte-to-char conversion.
    240         * @param input the <code>InputStream</code> to read from
    241         * @param output the <code>Writer</code> to write to
    242         * @throws IOException In case of an I/O problem
    243         */
    244        public static void copy(
    245                InputStream input,
    246                Writer output)
    247                    throws IOException {
    248            InputStreamReader in = new InputStreamReader(input);
    249            copy(in, output);
    250        }
    251
    252        /**
    253         * Copy and convert bytes from an <code>InputStream</code> to chars on a
    254         * <code>Writer</code>, using the specified encoding.
    255         * @param input the <code>InputStream</code> to read from
    256         * @param output the <code>Writer</code> to write to
    257         * @param encoding The name of a supported character encoding. See the
    258         * <a href="http://www.iana.org/assignments/character-sets">IANA
    259         * Charset Registry</a> for a list of valid encoding types.
    260         * @throws IOException In case of an I/O problem
    261         */
    262        public static void copy(
    263                InputStream input,
    264                Writer output,
    265                String encoding)
    266                    throws IOException {
    267            InputStreamReader in = new InputStreamReader(input, encoding);
    268            copy(in, output);
    269        }
    270
    271
    272        // ----------------------------------------------------------------
    273        // Reader -> OutputStream
    274        // ----------------------------------------------------------------
    275
    276        /**
    277         * Serialize chars from a <code>Reader</code> to bytes on an
    278         * <code>OutputStream</code>, and flush the <code>OutputStream</code>.
    279         * @param input the <code>Reader</code> to read from
    280         * @param output the <code>OutputStream</code> to write to
    281         * @throws IOException In case of an I/O problem
    282         */
    283        public static void copy(
    284                Reader input,
    285                OutputStream output)
    286                    throws IOException {
    287            OutputStreamWriter out = new OutputStreamWriter(output);
    288            copy(input, out);
    289            // XXX Unless anyone is planning on rewriting OutputStreamWriter, we
    290            // have to flush here.
    291            out.flush();
    292        }
    293
    294        // ----------------------------------------------------------------
    295        // String -> OutputStream
    296        // ----------------------------------------------------------------
    297
    298        /**
    299         * Serialize chars from a <code>String</code> to bytes on an
    300         * <code>OutputStream</code>, and
    301         * flush the <code>OutputStream</code>.
    302         * @param input the <code>String</code> to read from
    303         * @param output the <code>OutputStream</code> to write to
    304         * @throws IOException In case of an I/O problem
    305         */
    306        public static void copy(
    307                String input,
    308                OutputStream output)
    309                    throws IOException {
    310            StringReader in = new StringReader(input);
    311            OutputStreamWriter out = new OutputStreamWriter(output);
    312            copy(in, out);
    313            // XXX Unless anyone is planning on rewriting OutputStreamWriter, we
    314            // have to flush here.
    315            out.flush();
    316        }
    317
    318        // ----------------------------------------------------------------
    319        // String -> Writer
    320        // ----------------------------------------------------------------
    321
    322        /**
    323         * Copy chars from a <code>String</code> to a <code>Writer</code>.
    324         * @param input the <code>String</code> to read from
    325         * @param output the <code>Writer</code> to write to
    326         * @throws IOException In case of an I/O problem
    327         */
    328        public static void copy(String input, Writer output)
    329                    throws IOException {
    330            output.write(input);
    331        }
    332
    333    }