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 1.0
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
72 * (null if the stream is created with a file descriptor)
73 */
74 private final String path;
75
76 private final Object closeLock = new Object();
77 private volatile boolean closed = false;
78
79 /**
80 * Creates a file output stream to write to the file with the
81 * specified name. A new <code>FileDescriptor</code> object is
82 * created to represent this file connection.
83 * <p>
84 * First, if there is a security manager, its <code>checkWrite</code>
85 * method is called with <code>name</code> as its argument.
86 * <p>
87 * If the file exists but is a directory rather than a regular file, does
88 * not exist but cannot be created, or cannot be opened for any other
89 * reason then a <code>FileNotFoundException</code> is thrown.
90 *
91 * @param name the system-dependent filename
92 * @exception FileNotFoundException if the file exists but is a directory
93 * rather than a regular file, does not exist but cannot
94 * be created, or cannot be opened for any other reason
95 * @exception SecurityException if a security manager exists and its
96 * <code>checkWrite</code> method denies write access
97 * to the file.
98 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
99 */
100 public FileOutputStream(String name) throws FileNotFoundException {
101 this(name != null ? new File(name) : null, false);
102 }
103
104 /**
105 * Creates a file output stream to write to the file with the specified
106 * name. If the second argument is <code>true</code>, then
107 * bytes will be written to the end of the file rather than the beginning.
108 * A new <code>FileDescriptor</code> object is created to represent this
109 * file connection.
110 * <p>
111 * First, if there is a security manager, its <code>checkWrite</code>
112 * method is called with <code>name</code> as its argument.
113 * <p>
114 * If the file exists but is a directory rather than a regular file, does
115 * not exist but cannot be created, or cannot be opened for any other
116 * reason then a <code>FileNotFoundException</code> is thrown.
117 *
118 * @param name the system-dependent file name
119 * @param append if <code>true</code>, then bytes will be written
120 * to the end of the file rather than the beginning
121 * @exception FileNotFoundException if the file exists but is a directory
122 * rather than a regular file, does not exist but cannot
123 * be created, or cannot be opened for any other reason.
124 * @exception SecurityException if a security manager exists and its
125 * <code>checkWrite</code> method denies write access
126 * to the file.
127 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
128 * @since 1.1
129 */
130 public FileOutputStream(String name, boolean append)
131 throws FileNotFoundException
132 {
133 this(name != null ? new File(name) : null, append);
134 }
135
136 /**
137 * Creates a file output stream to write to the file represented by
138 * the specified <code>File</code> object. A new
139 * <code>FileDescriptor</code> object is created to represent this
140 * file connection.
141 * <p>
142 * First, if there is a security manager, its <code>checkWrite</code>
143 * method is called with the path represented by the <code>file</code>
144 * argument as its argument.
145 * <p>
146 * If the file exists but is a directory rather than a regular file, does
147 * not exist but cannot be created, or cannot be opened for any other
148 * reason then a <code>FileNotFoundException</code> is thrown.
149 *
150 * @param file the file to be opened for writing.
151 * @exception FileNotFoundException if the file exists but is a directory
152 * rather than a regular file, does not exist but cannot
153 * be created, or cannot be opened for any other reason
154 * @exception SecurityException if a security manager exists and its
155 * <code>checkWrite</code> method denies write access
156 * to the file.
157 * @see java.io.File#getPath()
158 * @see java.lang.SecurityException
159 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
160 */
161 public FileOutputStream(File file) throws FileNotFoundException {
162 this(file, false);
163 }
164
165 /**
166 * Creates a file output stream to write to the file represented by
167 * the specified <code>File</code> object. If the second argument is
168 * <code>true</code>, then bytes will be written to the end of the file
169 * rather than the beginning. A new <code>FileDescriptor</code> object is
170 * created to represent this file connection.
171 * <p>
172 * First, if there is a security manager, its <code>checkWrite</code>
173 * method is called with the path represented by the <code>file</code>
174 * argument as its argument.
175 * <p>
176 * If the file exists but is a directory rather than a regular file, does
177 * not exist but cannot be created, or cannot be opened for any other
178 * reason then a <code>FileNotFoundException</code> is thrown.
179 *
180 * @param file the file to be opened for writing.
181 * @param append if <code>true</code>, then bytes will be written
182 * to the end of the file rather than the beginning
183 * @exception FileNotFoundException if the file exists but is a directory
184 * rather than a regular file, does not exist but cannot
185 * be created, or cannot be opened for any other reason
186 * @exception SecurityException if a security manager exists and its
187 * <code>checkWrite</code> method denies write access
188 * to the file.
189 * @see java.io.File#getPath()
190 * @see java.lang.SecurityException
191 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
192 * @since 1.4
193 */
194 public FileOutputStream(File file, boolean append)
195 throws FileNotFoundException
196 {
197 String name = (file != null ? file.getPath() : null);
198 SecurityManager security = System.getSecurityManager();
199 if (security != null) {
200 security.checkWrite(name);
201 }
202 if (name == null) {
203 throw new NullPointerException();
204 }
205 if (file.isInvalid()) {
206 throw new FileNotFoundException("Invalid file path");
207 }
208 this.fd = new FileDescriptor();
209 fd.attach(this);
210 this.append = append;
211 this.path = name;
212
213 open(name, append);
214 }
215
216 /**
217 * Creates a file output stream to write to the specified file
218 * descriptor, which represents an existing connection to an actual
219 * file in the file system.
220 * <p>
221 * First, if there is a security manager, its <code>checkWrite</code>
222 * method is called with the file descriptor <code>fdObj</code>
223 * argument as its argument.
224 * <p>
225 * If <code>fdObj</code> is null then a <code>NullPointerException</code>
226 * is thrown.
227 * <p>
228 * This constructor does not throw an exception if <code>fdObj</code>
229 * is {@link java.io.FileDescriptor#valid() invalid}.
230 * However, if the methods are invoked on the resulting stream to attempt
231 * I/O on the stream, an <code>IOException</code> is thrown.
232 *
233 * @param fdObj the file descriptor to be opened for writing
234 * @exception SecurityException if a security manager exists and its
235 * <code>checkWrite</code> method denies
236 * write access to the file descriptor
237 * @see java.lang.SecurityManager#checkWrite(java.io.FileDescriptor)
238 */
239 public FileOutputStream(FileDescriptor fdObj) {
240 SecurityManager security = System.getSecurityManager();
241 if (fdObj == null) {
242 throw new NullPointerException();
243 }
244 if (security != null) {
245 security.checkWrite(fdObj);
246 }
247 this.fd = fdObj;
248 this.append = false;
249 this.path = null;
250
251 fd.attach(this);
252 }
253
254 /**
255 * Opens a file, with the specified name, for overwriting or appending.
256 * @param name name of file to be opened
257 * @param append whether the file is to be opened in append mode
258 */
259 private native void open(String name, boolean append)
260 throws FileNotFoundException;
261
262 /**
263 * Writes the specified byte to this file output stream.
264 *
265 * @param b the byte to be written.
266 * @param append {@code true} if the write operation first
267 * advances the position to the end of file
268 */
269 private native void write(int b, boolean append) throws IOException;
270
271 /**
272 * Writes the specified byte to this file output stream. Implements
273 * the <code>write</code> method of <code>OutputStream</code>.
274 *
275 * @param b the byte to be written.
276 * @exception IOException if an I/O error occurs.
277 */
278 public void write(int b) throws IOException {
279 write(b, append);
280 }
281
282 /**
283 * Writes a sub array as a sequence of bytes.
284 * @param b the data to be written
285 * @param off the start offset in the data
286 * @param len the number of bytes that are written
287 * @param append {@code true} to first advance the position to the
288 * end of file
289 * @exception IOException If an I/O error has occurred.
290 */
291 private native void writeBytes(byte b[], int off, int len, boolean append)
292 throws IOException;
293
294 /**
295 * Writes <code>b.length</code> bytes from the specified byte array
296 * to this file output stream.
297 *
298 * @param b the data.
299 * @exception IOException if an I/O error occurs.
300 */
301 public void write(byte b[]) throws IOException {
302 writeBytes(b, 0, b.length, append);
303 }
304
305 /**
306 * Writes <code>len</code> bytes from the specified byte array
307 * starting at offset <code>off</code> to this file output stream.
308 *
309 * @param b the data.
310 * @param off the start offset in the data.
311 * @param len the number of bytes to write.
312 * @exception IOException if an I/O error occurs.
313 */
314 public void write(byte b[], int off, int len) throws IOException {
315 writeBytes(b, off, len, append);
316 }
317
318 /**
319 * Closes this file output stream and releases any system resources
320 * associated with this stream. This file output stream may no longer
321 * be used for writing bytes.
322 *
323 * <p> If this stream has an associated channel then the channel is closed
324 * as well.
325 *
326 * @exception IOException if an I/O error occurs.
327 *
328 * @revised 1.4
329 * @spec JSR-51
330 */
331 public void close() throws IOException {
332 synchronized (closeLock) {
333 if (closed) {
334 return;
335 }
336 closed = true;
337 }
338
339 if (channel != null) {
340 channel.close();
341 }
342
343 fd.closeAll(new Closeable() {
344 public void close() throws IOException {
345 close0();
346 }
347 });
348 }
349
350 /**
351 * Returns the file descriptor associated with this stream.
352 *
353 * @return the <code>FileDescriptor</code> object that represents
354 * the connection to the file in the file system being used
355 * by this <code>FileOutputStream</code> object.
356 *
357 * @exception IOException if an I/O error occurs.
358 * @see java.io.FileDescriptor
359 */
360 public final FileDescriptor getFD() throws IOException {
361 if (fd != null) {
362 return fd;
363 }
364 throw new IOException();
365 }
366
367 /**
368 * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
369 * object associated with this file output stream.
370 *
371 * <p> The initial {@link java.nio.channels.FileChannel#position()
372 * position} of the returned channel will be equal to the
373 * number of bytes written to the file so far unless this stream is in
374 * append mode, in which case it will be equal to the size of the file.
375 * Writing bytes to this stream will increment the channel's position
376 * accordingly. Changing the channel's position, either explicitly or by
377 * writing, will change this stream's file position.
378 *
379 * @return the file channel associated with this file output stream
380 *
381 * @since 1.4
382 * @spec JSR-51
383 */
384 public FileChannel getChannel() {
385 synchronized (this) {
386 if (channel == null) {
387 channel = FileChannelImpl.open(fd, path, false, true, append, this);
388 }
389 return channel;
390 }
391 }
392
393 /**
394 * Cleans up the connection to the file, and ensures that the
395 * <code>close</code> method of this file output stream is
396 * called when there are no more references to this stream.
397 *
398 * @exception IOException if an I/O error occurs.
399 * @see java.io.FileInputStream#close()
400 */
401 protected void finalize() throws IOException {
402 if (fd != null) {
403 if (fd == FileDescriptor.out || fd == FileDescriptor.err) {
404 flush();
405 } else {
406 /* if fd is shared, the references in FileDescriptor
407 * will ensure that finalizer is only called when
408 * safe to do so. All references using the fd have
409 * become unreachable. We can call close()
410 */
411 close();
412 }
413 }
414 }
415
416 private native void close0() throws IOException;
417
418 private static native void initIDs();
419
420 static {
421 initIDs();
422 }
423
424 }