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 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 }