1 /*
2 * Copyright (c) 1994, 2008, 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 * @since JDK1.0
50 */
51 public
52 class FileOutputStream extends OutputStream
53 {
54 /**
55 * The system dependent file descriptor.
56 */
57 private final FileDescriptor fd;
58
59 /**
60 * True if the file is opened for append.
61 */
62 private final boolean append;
63
64 /**
65 * The associated channel, initalized lazily.
66 */
67 private FileChannel channel;
68
69 private final Object closeLock = new Object();
70 private volatile boolean closed = false;
71 private static final ThreadLocal<Boolean> runningFinalize =
72 new ThreadLocal<Boolean>();
73
74 private static boolean isRunningFinalize() {
75 Boolean val;
76 if ((val = runningFinalize.get()) != null)
77 return val.booleanValue();
78 return false;
79 }
80
81 /**
82 * Creates a file output stream to write to the file with the
83 * specified name. A new <code>FileDescriptor</code> object is
84 * created to represent this file connection.
85 * <p>
86 * First, if there is a security manager, its <code>checkWrite</code>
87 * method is called with <code>name</code> as its argument.
88 * <p>
89 * If the file exists but is a directory rather than a regular file, does
90 * not exist but cannot be created, or cannot be opened for any other
91 * reason then a <code>FileNotFoundException</code> is thrown.
92 *
93 * @param name the system-dependent filename
94 * @exception FileNotFoundException if the file exists but is a directory
95 * rather than a regular file, does not exist but cannot
96 * be created, or cannot be opened for any other reason
97 * @exception SecurityException if a security manager exists and its
98 * <code>checkWrite</code> method denies write access
99 * to the file.
100 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
101 */
102 public FileOutputStream(String name) throws FileNotFoundException {
103 this(name != null ? new File(name) : null, false);
104 }
105
106 /**
107 * Creates a file output stream to write to the file with the specified
108 * name. If the second argument is <code>true</code>, then
109 * bytes will be written to the end of the file rather than the beginning.
110 * A new <code>FileDescriptor</code> object is created to represent this
111 * file connection.
112 * <p>
113 * First, if there is a security manager, its <code>checkWrite</code>
114 * method is called with <code>name</code> as its argument.
115 * <p>
116 * If the file exists but is a directory rather than a regular file, does
117 * not exist but cannot be created, or cannot be opened for any other
118 * reason then a <code>FileNotFoundException</code> is thrown.
119 *
120 * @param name the system-dependent file name
121 * @param append if <code>true</code>, then bytes will be written
122 * to the end of the file rather than the beginning
123 * @exception FileNotFoundException if the file exists but is a directory
124 * rather than a regular file, does not exist but cannot
125 * be created, or cannot be opened for any other reason.
126 * @exception SecurityException if a security manager exists and its
127 * <code>checkWrite</code> method denies write access
128 * to the file.
129 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
130 * @since JDK1.1
131 */
132 public FileOutputStream(String name, boolean append)
133 throws FileNotFoundException
134 {
135 this(name != null ? new File(name) : null, append);
136 }
137
138 /**
139 * Creates a file output stream to write to the file represented by
140 * the specified <code>File</code> object. A new
141 * <code>FileDescriptor</code> object is created to represent this
142 * file connection.
143 * <p>
144 * First, if there is a security manager, its <code>checkWrite</code>
145 * method is called with the path represented by the <code>file</code>
146 * argument as its argument.
147 * <p>
148 * If the file exists but is a directory rather than a regular file, does
149 * not exist but cannot be created, or cannot be opened for any other
150 * reason then a <code>FileNotFoundException</code> is thrown.
151 *
152 * @param file the file to be opened for writing.
153 * @exception FileNotFoundException if the file exists but is a directory
154 * rather than a regular file, does not exist but cannot
155 * be created, or cannot be opened for any other reason
156 * @exception SecurityException if a security manager exists and its
157 * <code>checkWrite</code> method denies write access
158 * to the file.
159 * @see java.io.File#getPath()
160 * @see java.lang.SecurityException
161 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
162 */
163 public FileOutputStream(File file) throws FileNotFoundException {
164 this(file, false);
165 }
166
167 /**
168 * Creates a file output stream to write to the file represented by
169 * the specified <code>File</code> object. If the second argument is
170 * <code>true</code>, then bytes will be written to the end of the file
171 * rather than the beginning. A new <code>FileDescriptor</code> object is
172 * created to represent this file connection.
173 * <p>
174 * First, if there is a security manager, its <code>checkWrite</code>
175 * method is called with the path represented by the <code>file</code>
176 * argument as its argument.
177 * <p>
178 * If the file exists but is a directory rather than a regular file, does
179 * not exist but cannot be created, or cannot be opened for any other
180 * reason then a <code>FileNotFoundException</code> is thrown.
181 *
182 * @param file the file to be opened for writing.
183 * @param append if <code>true</code>, then bytes will be written
184 * to the end of the file rather than the beginning
185 * @exception FileNotFoundException if the file exists but is a directory
186 * rather than a regular file, does not exist but cannot
187 * be created, or cannot be opened for any other reason
188 * @exception SecurityException if a security manager exists and its
189 * <code>checkWrite</code> method denies write access
190 * to the file.
191 * @see java.io.File#getPath()
192 * @see java.lang.SecurityException
193 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
194 * @since 1.4
195 */
196 public FileOutputStream(File file, boolean append)
197 throws FileNotFoundException
198 {
199 String name = (file != null ? file.getPath() : null);
200 SecurityManager security = System.getSecurityManager();
201 if (security != null) {
202 security.checkWrite(name);
203 }
204 if (name == null) {
205 throw new NullPointerException();
206 }
207 this.fd = new FileDescriptor();
208 this.append = append;
209
210 fd.incrementAndGetUseCount();
211 open(name, append);
212 }
213
214 /**
215 * Creates a file output stream to write to the specified file
216 * descriptor, which represents an existing connection to an actual
217 * file in the file system.
218 * <p>
219 * First, if there is a security manager, its <code>checkWrite</code>
220 * method is called with the file descriptor <code>fdObj</code>
221 * argument as its argument.
222 * <p>
223 * If <code>fdObj</code> is null then a <code>NullPointerException</code>
224 * is thrown.
225 * <p>
226 * This constructor does not throw an exception if <code>fdObj</code>
227 * is {@link java.io.FileDescriptor#valid() invalid}.
228 * However, if the methods are invoked on the resulting stream to attempt
229 * I/O on the stream, an <code>IOException</code> is thrown.
230 *
231 * @param fdObj the file descriptor to be opened for writing
232 * @exception SecurityException if a security manager exists and its
233 * <code>checkWrite</code> method denies
234 * write access to the file descriptor
235 * @see java.lang.SecurityManager#checkWrite(java.io.FileDescriptor)
236 */
237 public FileOutputStream(FileDescriptor fdObj) {
238 SecurityManager security = System.getSecurityManager();
239 if (fdObj == null) {
240 throw new NullPointerException();
241 }
242 if (security != null) {
243 security.checkWrite(fdObj);
244 }
245 this.fd = fdObj;
246 this.append = false;
247
248 /*
249 * FileDescriptor is being shared by streams.
250 * Ensure that it's GC'ed only when all the streams/channels are done
251 * using it.
252 */
253 fd.incrementAndGetUseCount();
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 open(String name, boolean append)
262 throws FileNotFoundException;
263
264 /**
265 * Writes the specified byte to this file output stream.
266 *
267 * @param b the byte to be written.
268 * @param append {@code true} if the write operation first
269 * advances the position to the end of file
270 */
271 private native void write(int b, boolean append) throws IOException;
272
273 /**
274 * Writes the specified byte to this file output stream. Implements
275 * the <code>write</code> method of <code>OutputStream</code>.
276 *
277 * @param b the byte to be written.
278 * @exception IOException if an I/O error occurs.
279 */
280 public void write(int b) throws IOException {
281 write(b, append);
282 }
283
284 /**
285 * Writes a sub array as a sequence of bytes.
286 * @param b the data to be written
287 * @param off the start offset in the data
288 * @param len the number of bytes that are written
289 * @param append {@code true} to first advance the position to the
290 * end of file
291 * @exception IOException If an I/O error has occurred.
292 */
293 private native void writeBytes(byte b[], int off, int len, boolean append)
294 throws IOException;
295
296 /**
297 * Writes <code>b.length</code> bytes from the specified byte array
298 * to this file output stream.
299 *
300 * @param b the data.
301 * @exception IOException if an I/O error occurs.
302 */
303 public void write(byte b[]) throws IOException {
304 writeBytes(b, 0, b.length, append);
305 }
306
307 /**
308 * Writes <code>len</code> bytes from the specified byte array
309 * starting at offset <code>off</code> to this file output stream.
310 *
311 * @param b the data.
312 * @param off the start offset in the data.
313 * @param len the number of bytes to write.
314 * @exception IOException if an I/O error occurs.
315 */
316 public void write(byte b[], int off, int len) throws IOException {
317 writeBytes(b, off, len, append);
318 }
319
320 /**
321 * Closes this file output stream and releases any system resources
322 * associated with this stream. This file output stream may no longer
323 * be used for writing bytes.
324 *
325 * <p> If this stream has an associated channel then the channel is closed
326 * as well.
327 *
328 * @exception IOException if an I/O error occurs.
329 *
330 * @revised 1.4
331 * @spec JSR-51
332 */
333 public void close() throws IOException {
334 synchronized (closeLock) {
335 if (closed) {
336 return;
337 }
338 closed = true;
339 }
340
341 if (channel != null) {
342 /*
343 * Decrement FD use count associated with the channel
344 * The use count is incremented whenever a new channel
345 * is obtained from this stream.
346 */
347 fd.decrementAndGetUseCount();
348 channel.close();
349 }
350
351 /*
352 * Decrement FD use count associated with this stream
353 */
354 int useCount = fd.decrementAndGetUseCount();
355
356 /*
357 * If FileDescriptor is still in use by another stream, the finalizer
358 * will not close it.
359 */
360 if ((useCount <= 0) || !isRunningFinalize()) {
361 close0();
362 }
363 }
364
365 /**
366 * Returns the file descriptor associated with this stream.
367 *
368 * @return the <code>FileDescriptor</code> object that represents
369 * the connection to the file in the file system being used
370 * by this <code>FileOutputStream</code> object.
371 *
372 * @exception IOException if an I/O error occurs.
373 * @see java.io.FileDescriptor
374 */
375 public final FileDescriptor getFD() throws IOException {
376 if (fd != null) return fd;
377 throw new IOException();
378 }
379
380 /**
381 * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
382 * object associated with this file output stream. </p>
383 *
384 * <p> The initial {@link java.nio.channels.FileChannel#position()
385 * </code>position<code>} of the returned channel will be equal to the
386 * number of bytes written to the file so far unless this stream is in
387 * append mode, in which case it will be equal to the size of the file.
388 * Writing bytes to this stream will increment the channel's position
389 * accordingly. Changing the channel's position, either explicitly or by
390 * writing, will change this stream's file position.
391 *
392 * @return the file channel associated with this file output stream
393 *
394 * @since 1.4
395 * @spec JSR-51
396 */
397 public FileChannel getChannel() {
398 synchronized (this) {
399 if (channel == null) {
400 channel = FileChannelImpl.open(fd, false, true, append, this);
401
402 /*
403 * Increment fd's use count. Invoking the channel's close()
404 * method will result in decrementing the use count set for
405 * the channel.
406 */
407 fd.incrementAndGetUseCount();
408 }
409 return channel;
410 }
411 }
412
413 /**
414 * Cleans up the connection to the file, and ensures that the
415 * <code>close</code> method of this file output stream is
416 * called when there are no more references to this stream.
417 *
418 * @exception IOException if an I/O error occurs.
419 * @see java.io.FileInputStream#close()
420 */
421 protected void finalize() throws IOException {
422 if (fd != null) {
423 if (fd == FileDescriptor.out || fd == FileDescriptor.err) {
424 flush();
425 } else {
426
427 /*
428 * Finalizer should not release the FileDescriptor if another
429 * stream is still using it. If the user directly invokes
430 * close() then the FileDescriptor is also released.
431 */
432 runningFinalize.set(Boolean.TRUE);
433 try {
434 close();
435 } finally {
436 runningFinalize.set(Boolean.FALSE);
437 }
438 }
439 }
440 }
441
442 private native void close0() throws IOException;
443
444 private static native void initIDs();
445
446 static {
447 initIDs();
448 }
449
450 }