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