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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    * 
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   * 
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.io;
18  
19  import java.io.ByteArrayInputStream;
20  import java.io.IOException;
21  import java.io.InputStream;
22  import java.io.InputStreamReader;
23  import java.io.OutputStream;
24  import java.io.OutputStreamWriter;
25  import java.io.Reader;
26  import java.io.StringReader;
27  import java.io.Writer;
28  
29  /**
30   * This class provides static utility methods for buffered
31   * copying between sources (<code>InputStream</code>, <code>Reader</code>,
32   * <code>String</code> and <code>byte[]</code>) and destinations
33   * (<code>OutputStream</code>, <code>Writer</code>, <code>String</code> and
34   * <code>byte[]</code>).
35   * <p>
36   * Unless otherwise noted, these <code>copy</code> methods do <em>not</em>
37   * flush or close the streams. Often doing so would require making non-portable
38   * assumptions about the streams' origin and further use. This means that both
39   * streams' <code>close()</code> methods must be called after copying. if one
40   * omits this step, then the stream resources (sockets, file descriptors) are
41   * released when the associated Stream is garbage-collected. It is not a good
42   * idea to rely on this mechanism. For a good overview of the distinction
43   * between "memory management" and "resource management", see
44   * <a href="http://www.unixreview.com/articles/1998/9804/9804ja/ja.htm">this
45   * UnixReview article</a>.
46   * <p>
47   * For byte-to-char methods, a <code>copy</code> variant allows the encoding
48   * to be selected (otherwise the platform default is used). We would like to
49   * encourage you to always specify the encoding because relying on the platform
50   * default can lead to unexpected results.
51   * <p
52   * We don't provide special variants for the <code>copy</code> methods that
53   * let you specify the buffer size because in modern VMs the impact on speed
54   * seems to be minimal. We're using a default buffer size of 4 KB.
55   * <p>
56   * The <code>copy</code> methods use an internal buffer when copying. It is
57   * therefore advisable <em>not</em> to deliberately wrap the stream arguments
58   * to the <code>copy</code> methods in <code>Buffered*</code> streams. For
59   * example, don't do the following:
60   * <pre>
61   *  copy( new BufferedInputStream( in ), new BufferedOutputStream( out ) );
62   *  </pre>
63   * The rationale is as follows:
64   * <p>
65   * Imagine that an InputStream's read() is a very expensive operation, which
66   * would usually suggest wrapping in a BufferedInputStream. The
67   * BufferedInputStream works by issuing infrequent
68   * {@link java.io.InputStream#read(byte[] b, int off, int len)} requests on the
69   * underlying InputStream, to fill an internal buffer, from which further
70   * <code>read</code> requests can inexpensively get their data (until the buffer
71   * runs out).
72   * <p>
73   * However, the <code>copy</code> methods do the same thing, keeping an
74   * internal buffer, populated by
75   * {@link InputStream#read(byte[] b, int off, int len)} requests. Having two
76   * buffers (or three if the destination stream is also buffered) is pointless,
77   * and the unnecessary buffer management hurts performance slightly (about 3%,
78   * according to some simple experiments).
79   * <p>
80   * Behold, intrepid explorers; a map of this class:
81   * <pre>
82   *       Method      Input               Output          Dependency
83   *       ------      -----               ------          -------
84   * 1     copy        InputStream         OutputStream    (primitive)
85   * 2     copy        Reader              Writer          (primitive)
86   *
87   * 3     copy        InputStream         Writer          2
88   *
89   * 4     copy        Reader              OutputStream    2
90   *
91   * 5     copy        String              OutputStream    2
92   * 6     copy        String              Writer          (trivial)
93   *
94   * 7     copy        byte[]              Writer          3
95   * 8     copy        byte[]              OutputStream    (trivial)
96   * </pre>
97   * <p>
98   * Note that only the first two methods shuffle bytes; the rest use these
99   * 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 437680 2006-08-28 11:57:00Z scolebourne $
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 public class CopyUtils {
115 
116     /**
117      * The default size of the buffer.
118      */
119     private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;
120 
121     /**
122      * Instances should NOT be constructed in standard programming.
123      */
124     public CopyUtils() { }
125 
126     // ----------------------------------------------------------------
127     // byte[] -> OutputStream
128     // ----------------------------------------------------------------
129 
130     /**
131      * Copy bytes from a <code>byte[]</code> to an <code>OutputStream</code>.
132      * @param input the byte array to read from
133      * @param output the <code>OutputStream</code> to write to
134      * @throws IOException In case of an I/O problem
135      */
136     public static void copy(byte[] input, OutputStream output)
137             throws IOException {
138         output.write(input);
139     }
140 
141     // ----------------------------------------------------------------
142     // byte[] -> Writer
143     // ----------------------------------------------------------------
144 
145     /**
146      * Copy and convert bytes from a <code>byte[]</code> to chars on a
147      * <code>Writer</code>.
148      * The platform's default encoding is used for the byte-to-char conversion.
149      * @param input the byte array to read from
150      * @param output the <code>Writer</code> to write to
151      * @throws IOException In case of an I/O problem
152      */
153     public static void copy(byte[] input, Writer output)
154             throws IOException {
155         ByteArrayInputStream in = new ByteArrayInputStream(input);
156         copy(in, output);
157     }
158 
159 
160     /**
161      * Copy and convert bytes from a <code>byte[]</code> to chars on a
162      * <code>Writer</code>, using the specified encoding.
163      * @param input the byte array to read from
164      * @param output the <code>Writer</code> to write to
165      * @param encoding The name of a supported character encoding. See the
166      * <a href="http://www.iana.org/assignments/character-sets">IANA
167      * Charset Registry</a> for a list of valid encoding types.
168      * @throws IOException In case of an I/O problem
169      */
170     public static void copy(
171             byte[] input,
172             Writer output,
173             String encoding)
174                 throws IOException {
175         ByteArrayInputStream in = new ByteArrayInputStream(input);
176         copy(in, output, encoding);
177     }
178 
179 
180     // ----------------------------------------------------------------
181     // Core copy methods
182     // ----------------------------------------------------------------
183 
184     /**
185      * Copy bytes from an <code>InputStream</code> to an
186      * <code>OutputStream</code>.
187      * @param input the <code>InputStream</code> to read from
188      * @param output the <code>OutputStream</code> to write to
189      * @return the number of bytes copied
190      * @throws IOException In case of an I/O problem
191      */
192     public static int copy(
193             InputStream input,
194             OutputStream output)
195                 throws IOException {
196         byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
197         int count = 0;
198         int n = 0;
199         while (-1 != (n = input.read(buffer))) {
200             output.write(buffer, 0, n);
201             count += n;
202         }
203         return count;
204     }
205 
206     // ----------------------------------------------------------------
207     // Reader -> Writer
208     // ----------------------------------------------------------------
209 
210     /**
211      * Copy chars from a <code>Reader</code> to a <code>Writer</code>.
212      * @param input the <code>Reader</code> to read from
213      * @param output the <code>Writer</code> to write to
214      * @return the number of characters copied
215      * @throws IOException In case of an I/O problem
216      */
217     public static int copy(
218             Reader input,
219             Writer output)
220                 throws IOException {
221         char[] buffer = new char[DEFAULT_BUFFER_SIZE];
222         int count = 0;
223         int n = 0;
224         while (-1 != (n = input.read(buffer))) {
225             output.write(buffer, 0, n);
226             count += n;
227         }
228         return count;
229     }
230 
231     // ----------------------------------------------------------------
232     // InputStream -> Writer
233     // ----------------------------------------------------------------
234 
235     /**
236      * Copy and convert bytes from an <code>InputStream</code> to chars on a
237      * <code>Writer</code>.
238      * The platform's default encoding is used for the byte-to-char conversion.
239      * @param input the <code>InputStream</code> to read from
240      * @param output the <code>Writer</code> to write to
241      * @throws IOException In case of an I/O problem
242      */
243     public static void copy(
244             InputStream input,
245             Writer output)
246                 throws IOException {
247         InputStreamReader in = new InputStreamReader(input);
248         copy(in, output);
249     }
250 
251     /**
252      * Copy and convert bytes from an <code>InputStream</code> to chars on a
253      * <code>Writer</code>, using the specified encoding.
254      * @param input the <code>InputStream</code> to read from
255      * @param output the <code>Writer</code> to write to
256      * @param encoding The name of a supported character encoding. See the
257      * <a href="http://www.iana.org/assignments/character-sets">IANA
258      * Charset Registry</a> for a list of valid encoding types.
259      * @throws IOException In case of an I/O problem
260      */
261     public static void copy(
262             InputStream input,
263             Writer output,
264             String encoding)
265                 throws IOException {
266         InputStreamReader in = new InputStreamReader(input, encoding);
267         copy(in, output);
268     }
269 
270 
271     // ----------------------------------------------------------------
272     // Reader -> OutputStream
273     // ----------------------------------------------------------------
274 
275     /**
276      * Serialize chars from a <code>Reader</code> to bytes on an
277      * <code>OutputStream</code>, and flush the <code>OutputStream</code>.
278      * @param input the <code>Reader</code> to read from
279      * @param output the <code>OutputStream</code> to write to
280      * @throws IOException In case of an I/O problem
281      */
282     public static void copy(
283             Reader input,
284             OutputStream output)
285                 throws IOException {
286         OutputStreamWriter out = new OutputStreamWriter(output);
287         copy(input, out);
288         // XXX Unless anyone is planning on rewriting OutputStreamWriter, we
289         // have to flush here.
290         out.flush();
291     }
292 
293     // ----------------------------------------------------------------
294     // String -> OutputStream
295     // ----------------------------------------------------------------
296 
297     /**
298      * Serialize chars from a <code>String</code> to bytes on an
299      * <code>OutputStream</code>, and
300      * flush the <code>OutputStream</code>.
301      * @param input the <code>String</code> to read from
302      * @param output the <code>OutputStream</code> to write to
303      * @throws IOException In case of an I/O problem
304      */
305     public static void copy(
306             String input,
307             OutputStream output)
308                 throws IOException {
309         StringReader in = new StringReader(input);
310         OutputStreamWriter out = new OutputStreamWriter(output);
311         copy(in, out);
312         // XXX Unless anyone is planning on rewriting OutputStreamWriter, we
313         // have to flush here.
314         out.flush();
315     }
316 
317     // ----------------------------------------------------------------
318     // String -> Writer
319     // ----------------------------------------------------------------
320 
321     /**
322      * Copy chars from a <code>String</code> to a <code>Writer</code>.
323      * @param input the <code>String</code> to read from
324      * @param output the <code>Writer</code> to write to
325      * @throws IOException In case of an I/O problem
326      */
327     public static void copy(String input, Writer output)
328                 throws IOException {
329         output.write(input);
330     }
331 
332 }