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 ({@link InputStream}, {@link Reader},
035 * {@link String} and {@code byte[]}) and destinations
036 * ({@link OutputStream}, {@link Writer}, {@link 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 * Provenance: 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     * Copies bytes from a {@code byte[]} to an {@link OutputStream}.
118     * @param input the byte array to read from
119     * @param output the {@link OutputStream} to write to
120     * @throws IOException In case of an I/O problem
121     */
122    public static void copy(final byte[] input, final OutputStream output) throws IOException {
123        output.write(input);
124    }
125
126    /**
127     * Copies and convert bytes from a {@code byte[]} to chars on a
128     * {@link Writer}.
129     * The platform's default encoding is used for the byte-to-char conversion.
130     *
131     * @param input the byte array to read from
132     * @param output the {@link Writer} to write to
133     * @throws IOException In case of an I/O problem
134     * @deprecated 2.5 use {@link #copy(byte[], Writer, String)} instead
135     */
136    @Deprecated
137    public static void copy(final byte[] input, final Writer output) throws IOException {
138        final ByteArrayInputStream inputStream = new ByteArrayInputStream(input);
139        copy(inputStream, output);
140    }
141
142    /**
143     * Copies and convert bytes from a {@code byte[]} to chars on a
144     * {@link Writer}, using the specified encoding.
145     *
146     * @param input the byte array to read from
147     * @param output the {@link Writer} to write to
148     * @param encoding The name of a supported character encoding. See the
149     * <a href="http://www.iana.org/assignments/character-sets">IANA
150     * Charset Registry</a> for a list of valid encoding types.
151     * @throws IOException In case of an I/O problem
152     */
153    public static void copy(final byte[] input, final Writer output, final String encoding) throws IOException {
154        final ByteArrayInputStream inputStream = new ByteArrayInputStream(input);
155        copy(inputStream, output, encoding);
156    }
157
158    /**
159     * Copies bytes from an {@link InputStream} to an
160     * {@link OutputStream}.
161     *
162     * @param input the {@link InputStream} to read from
163     * @param output the {@link OutputStream} to write to
164     * @return the number of bytes copied
165     * @throws IOException In case of an I/O problem
166     */
167    public static int copy(final InputStream input, final OutputStream output) throws IOException {
168        final byte[] buffer = IOUtils.byteArray();
169        int count = 0;
170        int n;
171        while (EOF != (n = input.read(buffer))) {
172            output.write(buffer, 0, n);
173            count += n;
174        }
175        return count;
176    }
177
178    /**
179     * Copies and convert bytes from an {@link InputStream} to chars on a
180     * {@link Writer}.
181     * The platform's default encoding is used for the byte-to-char conversion.
182     *
183     * @param input the {@link InputStream} to read from
184     * @param output the {@link Writer} to write to
185     * @throws IOException In case of an I/O problem
186     * @deprecated 2.5 use {@link #copy(InputStream, Writer, String)} instead
187     */
188    @Deprecated
189    public static void copy(
190            final InputStream input,
191            final Writer output)
192                throws IOException {
193        // make explicit the dependency on the default encoding
194        final InputStreamReader in = new InputStreamReader(input, Charset.defaultCharset());
195        copy(in, output);
196    }
197
198    /**
199     * Copies and convert bytes from an {@link InputStream} to chars on a
200     * {@link Writer}, using the specified encoding.
201     *
202     * @param input the {@link InputStream} to read from
203     * @param output the {@link Writer} to write to
204     * @param encoding The name of a supported character encoding. See the
205     * <a href="http://www.iana.org/assignments/character-sets">IANA
206     * Charset Registry</a> for a list of valid encoding types.
207     * @throws IOException In case of an I/O problem
208     */
209    public static void copy(
210            final InputStream input,
211            final Writer output,
212            final String encoding)
213                throws IOException {
214        final InputStreamReader in = new InputStreamReader(input, encoding);
215        copy(in, output);
216    }
217
218    /**
219     * Serialize chars from a {@link Reader} to bytes on an
220     * {@link OutputStream}, and flush the {@link OutputStream}.
221     * Uses the default platform encoding.
222     *
223     * @param input the {@link Reader} to read from
224     * @param output the {@link OutputStream} to write to
225     * @throws IOException In case of an I/O problem
226     * @deprecated 2.5 use {@link #copy(Reader, OutputStream, String)} instead
227     */
228    @Deprecated
229    public static void copy(
230            final Reader input,
231            final OutputStream output)
232                throws IOException {
233        // make explicit the dependency on the default encoding
234        final OutputStreamWriter out = new OutputStreamWriter(output, Charset.defaultCharset());
235        copy(input, out);
236        // XXX Unless anyone is planning on rewriting OutputStreamWriter, we
237        // have to flush here.
238        out.flush();
239    }
240
241    /**
242     * Serialize chars from a {@link Reader} to bytes on an
243     * {@link OutputStream}, and flush the {@link OutputStream}.
244     *
245     * @param input the {@link Reader} to read from
246     * @param output the {@link OutputStream} to write to
247     * @param encoding The name of a supported character encoding. See the
248     * <a href="http://www.iana.org/assignments/character-sets">IANA
249     * Charset Registry</a> for a list of valid encoding types.
250     * @throws IOException In case of an I/O problem
251     * @since 2.5
252     */
253    public static void copy(
254            final Reader input,
255            final OutputStream output,
256            final String encoding)
257                throws IOException {
258        final OutputStreamWriter out = new OutputStreamWriter(output, encoding);
259        copy(input, out);
260        // XXX Unless anyone is planning on rewriting OutputStreamWriter, we
261        // have to flush here.
262        out.flush();
263    }
264
265    /**
266     * Copies chars from a {@link Reader} to a {@link Writer}.
267     *
268     * @param input the {@link Reader} to read from
269     * @param output the {@link Writer} to write to
270     * @return the number of characters copied
271     * @throws IOException In case of an I/O problem
272     */
273    public static int copy(
274            final Reader input,
275            final Writer output)
276                throws IOException {
277        final char[] buffer = IOUtils.getScratchCharArray();
278        int count = 0;
279        int n;
280        while (EOF != (n = input.read(buffer))) {
281            output.write(buffer, 0, n);
282            count += n;
283        }
284        return count;
285    }
286
287    /**
288     * Serialize chars from a {@link String} to bytes on an
289     * {@link OutputStream}, and
290     * flush the {@link OutputStream}.
291     * Uses the platform default encoding.
292     *
293     * @param input the {@link String} to read from
294     * @param output the {@link OutputStream} to write to
295     * @throws IOException In case of an I/O problem
296     * @deprecated 2.5 use {@link #copy(String, OutputStream, String)} instead
297     */
298    @Deprecated
299    public static void copy(
300            final String input,
301            final OutputStream output)
302                throws IOException {
303        final StringReader in = new StringReader(input);
304        // make explicit the dependency on the default encoding
305        final OutputStreamWriter out = new OutputStreamWriter(output, Charset.defaultCharset());
306        copy(in, out);
307        // XXX Unless anyone is planning on rewriting OutputStreamWriter, we
308        // have to flush here.
309        out.flush();
310    }
311
312    /**
313     * Serialize chars from a {@link String} to bytes on an
314     * {@link OutputStream}, and
315     * flush the {@link OutputStream}.
316     *
317     * @param input the {@link String} to read from
318     * @param output the {@link OutputStream} to write to
319     * @param encoding The name of a supported character encoding. See the
320     * <a href="http://www.iana.org/assignments/character-sets">IANA
321     * Charset Registry</a> for a list of valid encoding types.
322     * @throws IOException In case of an I/O problem
323     * @since 2.5
324     */
325    public static void copy(
326            final String input,
327            final OutputStream output,
328            final String encoding)
329                throws IOException {
330        final StringReader in = new StringReader(input);
331        final OutputStreamWriter out = new OutputStreamWriter(output, encoding);
332        copy(in, out);
333        // XXX Unless anyone is planning on rewriting OutputStreamWriter, we
334        // have to flush here.
335        out.flush();
336    }
337
338    /**
339     * Copies chars from a {@link String} to a {@link Writer}.
340     *
341     * @param input the {@link String} to read from
342     * @param output the {@link Writer} to write to
343     * @throws IOException In case of an I/O problem
344     */
345    public static void copy(final String input, final Writer output)
346                throws IOException {
347        output.write(input);
348    }
349
350    /**
351     * Instances should NOT be constructed in standard programming.
352     */
353    public CopyUtils() { }
354
355}