1 /*
2 * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.io;
27
28 import java.nio.channels.FileChannel;
29 import sun.nio.ch.FileChannelImpl;
30
31
32 /**
33 * A file output stream is an output stream for writing data to a
34 * <code>File</code> or to a <code>FileDescriptor</code>. Whether or not
35 * a file is available or may be created depends upon the underlying
36 * platform. Some platforms, in particular, allow a file to be opened
37 * for writing by only one <tt>FileOutputStream</tt> (or other
38 * file-writing object) at a time. In such situations the constructors in
39 * this class will fail if the file involved is already open.
40 *
41 * <p><code>FileOutputStream</code> is meant for writing streams of raw bytes
42 * such as image data. For writing streams of characters, consider using
43 * <code>FileWriter</code>.
44 *
45 * @author Arthur van Hoff
46 * @see java.io.File
47 * @see java.io.FileDescriptor
48 * @see java.io.FileInputStream
49 * @see java.nio.file.Files#newOutputStream
50 * @since JDK1.0
51 */
52 public
53 class FileOutputStream extends OutputStream
54 {
55 /**
56 * The system dependent file descriptor.
57 */
58 private final FileDescriptor fd;
59
60 /**
61 * True if the file is opened for append.
62 */
63 private final boolean append;
64
65 /**
66 * The associated channel, initialized lazily.
67 */
68 private FileChannel channel;
69
70 /**
71 * The path of the referenced file (null if the stream is created with a file descriptor)
72 */
73 private final String path;
74
75 private final Object closeLock = new Object();
76 private volatile boolean closed = false;
77
78 /**
79 * Creates a file output stream to write to the file with the
80 * specified name. A new <code>FileDescriptor</code> object is
81 * created to represent this file connection.
82 * <p>
83 * First, if there is a security manager, its <code>checkWrite</code>
84 * method is called with <code>name</code> as its argument.
85 * <p>
86 * If the file exists but is a directory rather than a regular file, does
87 * not exist but cannot be created, or cannot be opened for any other
88 * reason then a <code>FileNotFoundException</code> is thrown.
89 *
90 * @param name the system-dependent filename
91 * @exception FileNotFoundException if the file exists but is a directory
92 * rather than a regular file, does not exist but cannot
93 * be created, or cannot be opened for any other reason
94 * @exception SecurityException if a security manager exists and its
95 * <code>checkWrite</code> method denies write access
96 * to the file.
97 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
98 */
99 public FileOutputStream(String name) throws FileNotFoundException {
100 this(name != null ? new File(name) : null, false);
101 }
102
103 /**
104 * Creates a file output stream to write to the file with the specified
105 * name. If the second argument is <code>true</code>, then
106 * bytes will be written to the end of the file rather than the beginning.
107 * A new <code>FileDescriptor</code> object is created to represent this
108 * file connection.
109 * <p>
110 * First, if there is a security manager, its <code>checkWrite</code>
111 * method is called with <code>name</code> as its argument.
112 * <p>
113 * If the file exists but is a directory rather than a regular file, does
114 * not exist but cannot be created, or cannot be opened for any other
115 * reason then a <code>FileNotFoundException</code> is thrown.
116 *
117 * @param name the system-dependent file name
118 * @param append if <code>true</code>, then bytes will be written
119 * to the end of the file rather than the beginning
120 * @exception FileNotFoundException if the file exists but is a directory
121 * rather than a regular file, does not exist but cannot
122 * be created, or cannot be opened for any other reason.
123 * @exception SecurityException if a security manager exists and its
124 * <code>checkWrite</code> method denies write access
125 * to the file.
126 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
127 * @since JDK1.1
128 */
129 public FileOutputStream(String name, boolean append)
130 throws FileNotFoundException
131 {
132 this(name != null ? new File(name) : null, append);
133 }
134
135 /**
136 * Creates a file output stream to write to the file represented by
137 * the specified <code>File</code> object. A new
138 * <code>FileDescriptor</code> object is created to represent this
139 * file connection.
140 * <p>
141 * First, if there is a security manager, its <code>checkWrite</code>
142 * method is called with the path represented by the <code>file</code>
143 * argument as its argument.
144 * <p>
145 * If the file exists but is a directory rather than a regular file, does
146 * not exist but cannot be created, or cannot be opened for any other
147 * reason then a <code>FileNotFoundException</code> is thrown.
148 *
149 * @param file the file to be opened for writing.
150 * @exception FileNotFoundException if the file exists but is a directory
151 * rather than a regular file, does not exist but cannot
152 * be created, or cannot be opened for any other reason
153 * @exception SecurityException if a security manager exists and its
154 * <code>checkWrite</code> method denies write access
155 * to the file.
156 * @see java.io.File#getPath()
157 * @see java.lang.SecurityException
158 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
159 */
160 public FileOutputStream(File file) throws FileNotFoundException {
161 this(file, false);
162 }
163
164 /**
165 * Creates a file output stream to write to the file represented by
166 * the specified <code>File</code> object. If the second argument is
167 * <code>true</code>, then bytes will be written to the end of the file
168 * rather than the beginning. A new <code>FileDescriptor</code> object is
169 * created to represent this file connection.
170 * <p>
171 * First, if there is a security manager, its <code>checkWrite</code>
172 * method is called with the path represented by the <code>file</code>
173 * argument as its argument.
174 * <p>
175 * If the file exists but is a directory rather than a regular file, does
176 * not exist but cannot be created, or cannot be opened for any other
177 * reason then a <code>FileNotFoundException</code> is thrown.
178 *
179 * @param file the file to be opened for writing.
180 * @param append if <code>true</code>, then bytes will be written
181 * to the end of the file rather than the beginning
182 * @exception FileNotFoundException if the file exists but is a directory
183 * rather than a regular file, does not exist but cannot
184 * be created, or cannot be opened for any other reason
185 * @exception SecurityException if a security manager exists and its
186 * <code>checkWrite</code> method denies write access
187 * to the file.
188 * @see java.io.File#getPath()
189 * @see java.lang.SecurityException
190 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
191 * @since 1.4
192 */
193 public FileOutputStream(File file, boolean append)
194 throws FileNotFoundException
195 {
196 String name = (file != null ? file.getPath() : null);
197 SecurityManager security = System.getSecurityManager();
198 if (security != null) {
199 security.checkWrite(name);
200 }
201 if (name == null) {
202 throw new NullPointerException();
203 }
204 if (file.isInvalid()) {
205 throw new FileNotFoundException("Invalid file path");
206 }
207 this.fd = new FileDescriptor();
208 fd.attach(this);
209 this.append = append;
210 this.path = name;
211
212 open(name, append);
213 }
214
215 /**
216 * Creates a file output stream to write to the specified file
217 * descriptor, which represents an existing connection to an actual
218 * file in the file system.
219 * <p>
220 * First, if there is a security manager, its <code>checkWrite</code>
221 * method is called with the file descriptor <code>fdObj</code>
222 * argument as its argument.
223 * <p>
224 * If <code>fdObj</code> is null then a <code>NullPointerException</code>
225 * is thrown.
226 * <p>
227 * This constructor does not throw an exception if <code>fdObj</code>
228 * is {@link java.io.FileDescriptor#valid() invalid}.
229 * However, if the methods are invoked on the resulting stream to attempt
230 * I/O on the stream, an <code>IOException</code> is thrown.
231 *
232 * @param fdObj the file descriptor to be opened for writing
233 * @exception SecurityException if a security manager exists and its
234 * <code>checkWrite</code> method denies
235 * write access to the file descriptor
236 * @see java.lang.SecurityManager#checkWrite(java.io.FileDescriptor)
237 */
238 public FileOutputStream(FileDescriptor fdObj) {
239 SecurityManager security = System.getSecurityManager();
240 if (fdObj == null) {
241 throw new NullPointerException();
242 }
243 if (security != null) {
244 security.checkWrite(fdObj);
245 }
246 this.fd = fdObj;
247 this.append = false;
248 this.path = null;
249
250 fd.attach(this);
251 }
252
253 /**
254 * Opens a file, with the specified name, for overwriting or appending.
255 * @param name name of file to be opened
256 * @param append whether the file is to be opened in append mode
257 */
258 private native void open(String name, boolean append)
259 throws FileNotFoundException;
260
261 /**
262 * Writes the specified byte to this file output stream.
263 *
264 * @param b the byte to be written.
265 * @param append {@code true} if the write operation first
266 * advances the position to the end of file
267 */
268 private native void write(int b, boolean append) throws IOException;
269
270 /**
271 * Writes the specified byte to this file output stream. Implements
272 * the <code>write</code> method of <code>OutputStream</code>.
273 *
274 * @param b the byte to be written.
275 * @exception IOException if an I/O error occurs.
276 */
277 public void write(int b) throws IOException {
278 write(b, append);
279 }
280
281 /**
282 * Writes a sub array as a sequence of bytes.
283 * @param b the data to be written
284 * @param off the start offset in the data
285 * @param len the number of bytes that are written
286 * @param append {@code true} to first advance the position to the
287 * end of file
288 * @exception IOException If an I/O error has occurred.
289 */
290 private native void writeBytes(byte b[], int off, int len, boolean append)
291 throws IOException;
292
293 /**
294 * Writes <code>b.length</code> bytes from the specified byte array
295 * to this file output stream.
296 *
297 * @param b the data.
298 * @exception IOException if an I/O error occurs.
299 */
300 public void write(byte b[]) throws IOException {
301 writeBytes(b, 0, b.length, append);
302 }
303
304 /**
305 * Writes <code>len</code> bytes from the specified byte array
306 * starting at offset <code>off</code> to this file output stream.
307 *
308 * @param b the data.
309 * @param off the start offset in the data.
310 * @param len the number of bytes to write.
311 * @exception IOException if an I/O error occurs.
312 */
313 public void write(byte b[], int off, int len) throws IOException {
314 writeBytes(b, off, len, append);
315 }
316
317 /**
318 * Closes this file output stream and releases any system resources
319 * associated with this stream. This file output stream may no longer
320 * be used for writing bytes.
321 *
322 * <p> If this stream has an associated channel then the channel is closed
323 * as well.
324 *
325 * @exception IOException if an I/O error occurs.
326 *
327 * @revised 1.4
328 * @spec JSR-51
329 */
330 public void close() throws IOException {
331 synchronized (closeLock) {
332 if (closed) {
333 return;
334 }
335 closed = true;
336 }
337
338 if (channel != null) {
339 channel.close();
340 }
341
342 fd.closeAll(new Closeable() {
343 public void close() throws IOException {
344 close0();
345 }
346 });
347 }
348
349 /**
350 * Returns the file descriptor associated with this stream.
351 *
352 * @return the <code>FileDescriptor</code> object that represents
353 * the connection to the file in the file system being used
354 * by this <code>FileOutputStream</code> object.
355 *
356 * @exception IOException if an I/O error occurs.
357 * @see java.io.FileDescriptor
358 */
359 public final FileDescriptor getFD() throws IOException {
360 if (fd != null) {
361 return fd;
362 }
363 throw new IOException();
364 }
365
366 /**
367 * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
368 * object associated with this file output stream.
369 *
370 * <p> The initial {@link java.nio.channels.FileChannel#position()
371 * position} of the returned channel will be equal to the
372 * number of bytes written to the file so far unless this stream is in
373 * append mode, in which case it will be equal to the size of the file.
374 * Writing bytes to this stream will increment the channel's position
375 * accordingly. Changing the channel's position, either explicitly or by
376 * writing, will change this stream's file position.
377 *
378 * @return the file channel associated with this file output stream
379 *
380 * @since 1.4
381 * @spec JSR-51
382 */
383 public FileChannel getChannel() {
384 synchronized (this) {
385 if (channel == null) {
386 channel = FileChannelImpl.open(fd, path, false, true, append, this);
387 }
388 return channel;
389 }
390 }
391
392 /**
393 * Cleans up the connection to the file, and ensures that the
394 * <code>close</code> method of this file output stream is
395 * called when there are no more references to this stream.
396 *
397 * @exception IOException if an I/O error occurs.
398 * @see java.io.FileInputStream#close()
399 */
400 protected void finalize() throws IOException {
401 if (fd != null) {
402 if (fd == FileDescriptor.out || fd == FileDescriptor.err) {
403 flush();
404 } else {
405 /* if fd is shared, the references in FileDescriptor
406 * will ensure that finalizer is only called when
407 * safe to do so. All references using the fd have
408 * become unreachable. We can call close()
409 */
410 close();
411 }
412 }
413 }
414
415 private native void close0() throws IOException;
416
417 private static native void initIDs();
418
419 static {
420 initIDs();
421 }
422
423 }