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 jdk.internal.misc.SharedSecrets;
30 import jdk.internal.misc.JavaIOFileDescriptorAccess;
31 import sun.nio.ch.FileChannelImpl;
32
33
34 /**
35 * A file output stream is an output stream for writing data to a
36 * <code>File</code> or to a <code>FileDescriptor</code>. Whether or not
37 * a file is available or may be created depends upon the underlying
38 * platform. Some platforms, in particular, allow a file to be opened
39 * for writing by only one {@code FileOutputStream} (or other
40 * file-writing object) at a time. In such situations the constructors in
41 * this class will fail if the file involved is already open.
42 *
43 * <p><code>FileOutputStream</code> is meant for writing streams of raw bytes
44 * such as image data. For writing streams of characters, consider using
45 * <code>FileWriter</code>.
46 *
47 * @author Arthur van Hoff
48 * @see java.io.File
49 * @see java.io.FileDescriptor
50 * @see java.io.FileInputStream
51 * @see java.nio.file.Files#newOutputStream
52 * @since 1.0
53 */
54 public
55 class FileOutputStream extends OutputStream
56 {
57 /**
58 * Access to FileDescriptor internals.
59 */
60 private static final JavaIOFileDescriptorAccess fdAccess =
61 SharedSecrets.getJavaIOFileDescriptorAccess();
62
63 /**
64 * The system dependent file descriptor.
65 */
66 private final FileDescriptor fd;
67
68 /**
69 * The associated channel, initialized lazily.
70 */
71 private volatile FileChannel channel;
72
73 /**
74 * The path of the referenced file
75 * (null if the stream is created with a file descriptor)
76 */
77 private final String path;
78
79 private final Object closeLock = new Object();
80
81 private volatile boolean closed;
82
83 /**
84 * Creates a file output stream to write to the file with the
85 * specified name. A new <code>FileDescriptor</code> object is
86 * created to represent this file connection.
87 * <p>
88 * First, if there is a security manager, its <code>checkWrite</code>
89 * method is called with <code>name</code> as its argument.
90 * <p>
91 * If the file exists but is a directory rather than a regular file, does
92 * not exist but cannot be created, or cannot be opened for any other
93 * reason then a <code>FileNotFoundException</code> is thrown.
94 *
95 * @param name the system-dependent filename
96 * @exception FileNotFoundException if the file exists but is a directory
97 * rather than a regular file, does not exist but cannot
98 * be created, or cannot be opened for any other reason
99 * @exception SecurityException if a security manager exists and its
100 * <code>checkWrite</code> method denies write access
101 * to the file.
102 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
103 */
104 public FileOutputStream(String name) throws FileNotFoundException {
105 this(name != null ? new File(name) : null, false);
106 }
107
108 /**
109 * Creates a file output stream to write to the file with the specified
110 * name. If the second argument is <code>true</code>, then
111 * bytes will be written to the end of the file rather than the beginning.
112 * A new <code>FileDescriptor</code> object is created to represent this
113 * file connection.
114 * <p>
115 * First, if there is a security manager, its <code>checkWrite</code>
116 * method is called with <code>name</code> as its argument.
117 * <p>
118 * If the file exists but is a directory rather than a regular file, does
119 * not exist but cannot be created, or cannot be opened for any other
120 * reason then a <code>FileNotFoundException</code> is thrown.
121 *
122 * @param name the system-dependent file name
123 * @param append if <code>true</code>, then bytes will be written
124 * to the end of the file rather than the beginning
125 * @exception FileNotFoundException if the file exists but is a directory
126 * rather than a regular file, does not exist but cannot
127 * be created, or cannot be opened for any other reason.
128 * @exception SecurityException if a security manager exists and its
129 * <code>checkWrite</code> method denies write access
130 * to the file.
131 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
132 * @since 1.1
133 */
134 public FileOutputStream(String name, boolean append)
135 throws FileNotFoundException
136 {
137 this(name != null ? new File(name) : null, append);
138 }
139
140 /**
141 * Creates a file output stream to write to the file represented by
142 * the specified <code>File</code> object. A new
143 * <code>FileDescriptor</code> object is created to represent this
144 * file connection.
145 * <p>
146 * First, if there is a security manager, its <code>checkWrite</code>
147 * method is called with the path represented by the <code>file</code>
148 * argument as its argument.
149 * <p>
150 * If the file exists but is a directory rather than a regular file, does
151 * not exist but cannot be created, or cannot be opened for any other
152 * reason then a <code>FileNotFoundException</code> is thrown.
153 *
154 * @param file the file to be opened for writing.
155 * @exception FileNotFoundException if the file exists but is a directory
156 * rather than a regular file, does not exist but cannot
157 * be created, or cannot be opened for any other reason
158 * @exception SecurityException if a security manager exists and its
159 * <code>checkWrite</code> method denies write access
160 * to the file.
161 * @see java.io.File#getPath()
162 * @see java.lang.SecurityException
163 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
164 */
165 public FileOutputStream(File file) throws FileNotFoundException {
166 this(file, false);
167 }
168
169 /**
170 * Creates a file output stream to write to the file represented by
171 * the specified <code>File</code> object. If the second argument is
172 * <code>true</code>, then bytes will be written to the end of the file
173 * rather than the beginning. A new <code>FileDescriptor</code> object is
174 * created to represent this file connection.
175 * <p>
176 * First, if there is a security manager, its <code>checkWrite</code>
177 * method is called with the path represented by the <code>file</code>
178 * argument as its argument.
179 * <p>
180 * If the file exists but is a directory rather than a regular file, does
181 * not exist but cannot be created, or cannot be opened for any other
182 * reason then a <code>FileNotFoundException</code> is thrown.
183 *
184 * @param file the file to be opened for writing.
185 * @param append if <code>true</code>, then bytes will be written
186 * to the end of the file rather than the beginning
187 * @exception FileNotFoundException if the file exists but is a directory
188 * rather than a regular file, does not exist but cannot
189 * be created, or cannot be opened for any other reason
190 * @exception SecurityException if a security manager exists and its
191 * <code>checkWrite</code> method denies write access
192 * to the file.
193 * @see java.io.File#getPath()
194 * @see java.lang.SecurityException
195 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
196 * @since 1.4
197 */
198 public FileOutputStream(File file, boolean append)
199 throws FileNotFoundException
200 {
201 String name = (file != null ? file.getPath() : null);
202 SecurityManager security = System.getSecurityManager();
203 if (security != null) {
204 security.checkWrite(name);
205 }
206 if (name == null) {
207 throw new NullPointerException();
208 }
209 if (file.isInvalid()) {
210 throw new FileNotFoundException("Invalid file path");
211 }
212 this.fd = new FileDescriptor();
213 fd.attach(this);
214 this.path = name;
215
216 open(name, append);
217 }
218
219 /**
220 * Creates a file output stream to write to the specified file
221 * descriptor, which represents an existing connection to an actual
222 * file in the file system.
223 * <p>
224 * First, if there is a security manager, its <code>checkWrite</code>
225 * method is called with the file descriptor <code>fdObj</code>
226 * argument as its argument.
227 * <p>
228 * If <code>fdObj</code> is null then a <code>NullPointerException</code>
229 * is thrown.
230 * <p>
231 * This constructor does not throw an exception if <code>fdObj</code>
232 * is {@link java.io.FileDescriptor#valid() invalid}.
233 * However, if the methods are invoked on the resulting stream to attempt
234 * I/O on the stream, an <code>IOException</code> is thrown.
235 *
236 * @param fdObj the file descriptor to be opened for writing
237 * @exception SecurityException if a security manager exists and its
238 * <code>checkWrite</code> method denies
239 * write access to the file descriptor
240 * @see java.lang.SecurityManager#checkWrite(java.io.FileDescriptor)
241 */
242 public FileOutputStream(FileDescriptor fdObj) {
243 SecurityManager security = System.getSecurityManager();
244 if (fdObj == null) {
245 throw new NullPointerException();
246 }
247 if (security != null) {
248 security.checkWrite(fdObj);
249 }
250 this.fd = fdObj;
251 this.path = null;
252
253 fd.attach(this);
254 }
255
256 /**
257 * Opens a file, with the specified name, for overwriting or appending.
258 * @param name name of file to be opened
259 * @param append whether the file is to be opened in append mode
260 */
261 private native void open0(String name, boolean append)
262 throws FileNotFoundException;
263
264 // wrap native call to allow instrumentation
265 /**
266 * Opens a file, with the specified name, for overwriting or appending.
267 * @param name name of file to be opened
268 * @param append whether the file is to be opened in append mode
269 */
270 private void open(String name, boolean append)
271 throws FileNotFoundException {
272 open0(name, append);
273 }
274
275 /**
276 * Writes the specified byte to this file output stream.
277 *
278 * @param b the byte to be written.
279 * @param append {@code true} if the write operation first
280 * advances the position to the end of file
281 */
282 private native void write(int b, boolean append) throws IOException;
283
284 /**
285 * Writes the specified byte to this file output stream. Implements
286 * the <code>write</code> method of <code>OutputStream</code>.
287 *
288 * @param b the byte to be written.
289 * @exception IOException if an I/O error occurs.
290 */
291 public void write(int b) throws IOException {
292 write(b, fdAccess.getAppend(fd));
293 }
294
295 /**
296 * Writes a sub array as a sequence of bytes.
297 * @param b the data to be written
298 * @param off the start offset in the data
299 * @param len the number of bytes that are written
300 * @param append {@code true} to first advance the position to the
301 * end of file
302 * @exception IOException If an I/O error has occurred.
303 */
304 private native void writeBytes(byte b[], int off, int len, boolean append)
305 throws IOException;
306
307 /**
308 * Writes <code>b.length</code> bytes from the specified byte array
309 * to this file output stream.
310 *
311 * @param b the data.
312 * @exception IOException if an I/O error occurs.
313 */
314 public void write(byte b[]) throws IOException {
315 writeBytes(b, 0, b.length, fdAccess.getAppend(fd));
316 }
317
318 /**
319 * Writes <code>len</code> bytes from the specified byte array
320 * starting at offset <code>off</code> to this file output stream.
321 *
322 * @param b the data.
323 * @param off the start offset in the data.
324 * @param len the number of bytes to write.
325 * @exception IOException if an I/O error occurs.
326 */
327 public void write(byte b[], int off, int len) throws IOException {
328 writeBytes(b, off, len, fdAccess.getAppend(fd));
329 }
330
331 /**
332 * Closes this file output stream and releases any system resources
333 * associated with this stream. This file output stream may no longer
334 * be used for writing bytes.
335 *
336 * <p> If this stream has an associated channel then the channel is closed
337 * as well.
338 *
339 * @exception IOException if an I/O error occurs.
340 *
341 * @revised 1.4
342 * @spec JSR-51
343 */
344 public void close() throws IOException {
345 if (closed) {
346 return;
347 }
348 synchronized (closeLock) {
349 if (closed) {
350 return;
351 }
352 closed = true;
353 }
354
355 FileChannel fc = channel;
356 if (fc != null) {
357 fc.close();
358 }
359
360 fd.closeAll(new Closeable() {
361 public void close() throws IOException {
362 close0();
363 }
364 });
365 }
366
367 /**
368 * Returns the file descriptor associated with this stream.
369 *
370 * @return the <code>FileDescriptor</code> object that represents
371 * the connection to the file in the file system being used
372 * by this <code>FileOutputStream</code> object.
373 *
374 * @exception IOException if an I/O error occurs.
375 * @see java.io.FileDescriptor
376 */
377 public final FileDescriptor getFD() throws IOException {
378 if (fd != null) {
379 return fd;
380 }
381 throw new IOException();
382 }
383
384 /**
385 * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
386 * object associated with this file output stream.
387 *
388 * <p> The initial {@link java.nio.channels.FileChannel#position()
389 * position} of the returned channel will be equal to the
390 * number of bytes written to the file so far unless this stream is in
391 * append mode, in which case it will be equal to the size of the file.
392 * Writing bytes to this stream will increment the channel's position
393 * accordingly. Changing the channel's position, either explicitly or by
394 * writing, will change this stream's file position.
395 *
396 * @return the file channel associated with this file output stream
397 *
398 * @since 1.4
399 * @spec JSR-51
400 */
401 public FileChannel getChannel() {
402 FileChannel fc = this.channel;
403 if (fc == null) {
404 synchronized (this) {
405 fc = this.channel;
406 if (fc == null) {
407 this.channel = fc = FileChannelImpl.open(fd, path, false, true, this);
408 if (closed) {
409 try {
410 fc.close();
411 } catch (IOException ioe) {
412 throw new InternalError(ioe); // should not happen
413 }
414 }
415 }
416 }
417 }
418 return fc;
419 }
420
421 /**
422 * Cleans up the connection to the file, and ensures that the
423 * <code>close</code> method of this file output stream is
424 * called when there are no more references to this stream.
425 *
426 * @exception IOException if an I/O error occurs.
427 * @see java.io.FileInputStream#close()
428 */
429 protected void finalize() throws IOException {
430 if (fd != null) {
431 if (fd == FileDescriptor.out || fd == FileDescriptor.err) {
432 flush();
433 } else {
434 /* if fd is shared, the references in FileDescriptor
435 * will ensure that finalizer is only called when
436 * safe to do so. All references using the fd have
437 * become unreachable. We can call close()
438 */
439 close();
440 }
441 }
442 }
443
444 private native void close0() throws IOException;
445
446 private static native void initIDs();
447
448 static {
449 initIDs();
450 }
451
452 }