1 /*
2 * Copyright (c) 1994, 2011, 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 import sun.misc.IoTrace;
31 import sun.misc.IoTraceContext;
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 <tt>FileOutputStream</tt> (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 JDK1.0
53 */
54 public
55 class FileOutputStream extends OutputStream
56 {
57 /**
58 * The system dependent file descriptor.
59 */
60 private final FileDescriptor fd;
61
62 /**
63 * The path of the referenced file (null if the stream is created with a file descriptor)
64 */
65 private final String path;
66
67 /**
68 * True if the file is opened for append.
69 */
70 private final boolean append;
71
72 /**
73 * The associated channel, initialized lazily.
74 */
75 private FileChannel channel;
76
77 private final Object closeLock = new Object();
78 private volatile boolean closed = false;
79
80 /**
81 * Creates a file output stream to write to the file with the
82 * specified name. A new <code>FileDescriptor</code> object is
83 * created to represent this file connection.
84 * <p>
85 * First, if there is a security manager, its <code>checkWrite</code>
86 * method is called with <code>name</code> as its argument.
87 * <p>
88 * If the file exists but is a directory rather than a regular file, does
89 * not exist but cannot be created, or cannot be opened for any other
90 * reason then a <code>FileNotFoundException</code> is thrown.
91 *
92 * @param name the system-dependent filename
93 * @exception FileNotFoundException if the file exists but is a directory
94 * rather than a regular file, does not exist but cannot
95 * be created, or cannot be opened for any other reason
96 * @exception SecurityException if a security manager exists and its
97 * <code>checkWrite</code> method denies write access
98 * to the file.
99 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
100 */
101 public FileOutputStream(String name) throws FileNotFoundException {
102 this(name != null ? new File(name) : null, false);
103 }
104
105 /**
106 * Creates a file output stream to write to the file with the specified
107 * name. If the second argument is <code>true</code>, then
108 * bytes will be written to the end of the file rather than the beginning.
109 * A new <code>FileDescriptor</code> object is created to represent this
110 * file connection.
111 * <p>
112 * First, if there is a security manager, its <code>checkWrite</code>
113 * method is called with <code>name</code> as its argument.
114 * <p>
115 * If the file exists but is a directory rather than a regular file, does
116 * not exist but cannot be created, or cannot be opened for any other
117 * reason then a <code>FileNotFoundException</code> is thrown.
118 *
119 * @param name the system-dependent file name
120 * @param append if <code>true</code>, then bytes will be written
121 * to the end of the file rather than the beginning
122 * @exception FileNotFoundException if the file exists but is a directory
123 * rather than a regular file, does not exist but cannot
124 * be created, or cannot be opened for any other reason.
125 * @exception SecurityException if a security manager exists and its
126 * <code>checkWrite</code> method denies write access
127 * to the file.
128 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
129 * @since JDK1.1
130 */
131 public FileOutputStream(String name, boolean append)
132 throws FileNotFoundException
133 {
134 this(name != null ? new File(name) : null, append);
135 }
136
137 /**
138 * Creates a file output stream to write to the file represented by
139 * the specified <code>File</code> object. A new
140 * <code>FileDescriptor</code> object is created to represent this
141 * file connection.
142 * <p>
143 * First, if there is a security manager, its <code>checkWrite</code>
144 * method is called with the path represented by the <code>file</code>
145 * argument as its argument.
146 * <p>
147 * If the file exists but is a directory rather than a regular file, does
148 * not exist but cannot be created, or cannot be opened for any other
149 * reason then a <code>FileNotFoundException</code> is thrown.
150 *
151 * @param file the file to be opened for writing.
152 * @exception FileNotFoundException if the file exists but is a directory
153 * rather than a regular file, does not exist but cannot
154 * be created, or cannot be opened for any other reason
155 * @exception SecurityException if a security manager exists and its
156 * <code>checkWrite</code> method denies write access
157 * to the file.
158 * @see java.io.File#getPath()
159 * @see java.lang.SecurityException
160 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
161 */
162 public FileOutputStream(File file) throws FileNotFoundException {
163 this(file, false);
164 }
165
166 /**
167 * Creates a file output stream to write to the file represented by
168 * the specified <code>File</code> object. If the second argument is
169 * <code>true</code>, then bytes will be written to the end of the file
170 * rather than the beginning. A new <code>FileDescriptor</code> object is
171 * created to represent this file connection.
172 * <p>
173 * First, if there is a security manager, its <code>checkWrite</code>
174 * method is called with the path represented by the <code>file</code>
175 * argument as its argument.
176 * <p>
177 * If the file exists but is a directory rather than a regular file, does
178 * not exist but cannot be created, or cannot be opened for any other
179 * reason then a <code>FileNotFoundException</code> is thrown.
180 *
181 * @param file the file to be opened for writing.
182 * @param append if <code>true</code>, then bytes will be written
183 * to the end of the file rather than the beginning
184 * @exception FileNotFoundException if the file exists but is a directory
185 * rather than a regular file, does not exist but cannot
186 * be created, or cannot be opened for any other reason
187 * @exception SecurityException if a security manager exists and its
188 * <code>checkWrite</code> method denies write access
189 * to the file.
190 * @see java.io.File#getPath()
191 * @see java.lang.SecurityException
192 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
193 * @since 1.4
194 */
195 public FileOutputStream(File file, boolean append)
196 throws FileNotFoundException
197 {
198 String name = (file != null ? file.getPath() : null);
199 SecurityManager security = System.getSecurityManager();
200 if (security != null) {
201 security.checkWrite(name);
202 }
203 if (name == null) {
204 throw new NullPointerException();
205 }
206 this.fd = new FileDescriptor();
207 fd.attach(this);
208 this.append = append;
209 this.path = name;
210 open(name, append);
211 }
212
213 /**
214 * Creates a file output stream to write to the specified file
215 * descriptor, which represents an existing connection to an actual
216 * file in the file system.
217 * <p>
218 * First, if there is a security manager, its <code>checkWrite</code>
219 * method is called with the file descriptor <code>fdObj</code>
220 * argument as its argument.
221 * <p>
222 * If <code>fdObj</code> is null then a <code>NullPointerException</code>
223 * is thrown.
224 * <p>
225 * This constructor does not throw an exception if <code>fdObj</code>
226 * is {@link java.io.FileDescriptor#valid() invalid}.
227 * However, if the methods are invoked on the resulting stream to attempt
228 * I/O on the stream, an <code>IOException</code> is thrown.
229 *
230 * @param fdObj the file descriptor to be opened for writing
231 * @exception SecurityException if a security manager exists and its
232 * <code>checkWrite</code> method denies
233 * write access to the file descriptor
234 * @see java.lang.SecurityManager#checkWrite(java.io.FileDescriptor)
235 */
236 public FileOutputStream(FileDescriptor fdObj) {
237 SecurityManager security = System.getSecurityManager();
238 if (fdObj == null) {
239 throw new NullPointerException();
240 }
241 if (security != null) {
242 security.checkWrite(fdObj);
243 }
244 this.fd = fdObj;
245 this.path = null;
246 this.append = false;
247
248 fd.attach(this);
249 }
250
251 /**
252 * Opens a file, with the specified name, for overwriting or appending.
253 * @param name name of file to be opened
254 * @param append whether the file is to be opened in append mode
255 */
256 private native void open(String name, boolean append)
257 throws FileNotFoundException;
258
259 /**
260 * Writes the specified byte to this file output stream.
261 *
262 * @param b the byte to be written.
263 * @param append {@code true} if the write operation first
264 * advances the position to the end of file
265 */
266 private native void write(int b, boolean append) throws IOException;
267
268 /**
269 * Writes the specified byte to this file output stream. Implements
270 * the <code>write</code> method of <code>OutputStream</code>.
271 *
272 * @param b the byte to be written.
273 * @exception IOException if an I/O error occurs.
274 */
275 public void write(int b) throws IOException {
276 IoTraceContext traceContext = IoTrace.fileWriteBegin(path);
277 int bytesWritten = 0;
278 try {
279 write(b, append);
280 bytesWritten = 1;
281 } finally {
282 IoTrace.fileWriteEnd(traceContext, bytesWritten);
283 }
284 }
285
286 /**
287 * Writes a sub array as a sequence of bytes.
288 * @param b the data to be written
289 * @param off the start offset in the data
290 * @param len the number of bytes that are written
291 * @param append {@code true} to first advance the position to the
292 * end of file
293 * @exception IOException If an I/O error has occurred.
294 */
295 private native void writeBytes(byte b[], int off, int len, boolean append)
296 throws IOException;
297
298 /**
299 * Writes <code>b.length</code> bytes from the specified byte array
300 * to this file output stream.
301 *
302 * @param b the data.
303 * @exception IOException if an I/O error occurs.
304 */
305 public void write(byte b[]) throws IOException {
306 IoTraceContext traceContext = IoTrace.fileWriteBegin(path);
307 int bytesWritten = 0;
308 try {
309 writeBytes(b, 0, b.length, append);
310 bytesWritten = b.length;
311 } finally {
312 IoTrace.fileWriteEnd(traceContext, bytesWritten);
313 }
314 }
315
316 /**
317 * Writes <code>len</code> bytes from the specified byte array
318 * starting at offset <code>off</code> to this file output stream.
319 *
320 * @param b the data.
321 * @param off the start offset in the data.
322 * @param len the number of bytes to write.
323 * @exception IOException if an I/O error occurs.
324 */
325 public void write(byte b[], int off, int len) throws IOException {
326 IoTraceContext traceContext = IoTrace.fileWriteBegin(path);
327 int bytesWritten = 0;
328 try {
329 writeBytes(b, off, len, append);
330 bytesWritten = len;
331 } finally {
332 IoTrace.fileWriteEnd(traceContext, bytesWritten);
333 }
334 }
335
336 /**
337 * Closes this file output stream and releases any system resources
338 * associated with this stream. This file output stream may no longer
339 * be used for writing bytes.
340 *
341 * <p> If this stream has an associated channel then the channel is closed
342 * as well.
343 *
344 * @exception IOException if an I/O error occurs.
345 *
346 * @revised 1.4
347 * @spec JSR-51
348 */
349 public void close() throws IOException {
350 synchronized (closeLock) {
351 if (closed) {
352 return;
353 }
354 closed = true;
355 }
356
357 if (channel != null) {
358 channel.close();
359 }
360
361 fd.closeAll(new Closeable() {
362 public void close() throws IOException {
363 close0();
364 }
365 });
366 }
367
368 /**
369 * Returns the file descriptor associated with this stream.
370 *
371 * @return the <code>FileDescriptor</code> object that represents
372 * the connection to the file in the file system being used
373 * by this <code>FileOutputStream</code> object.
374 *
375 * @exception IOException if an I/O error occurs.
376 * @see java.io.FileDescriptor
377 */
378 public final FileDescriptor getFD() throws IOException {
379 if (fd != null) {
380 return fd;
381 }
382 throw new IOException();
383 }
384
385 /**
386 * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
387 * object associated with this file output stream. </p>
388 *
389 * <p> The initial {@link java.nio.channels.FileChannel#position()
390 * </code>position<code>} of the returned channel will be equal to the
391 * number of bytes written to the file so far unless this stream is in
392 * append mode, in which case it will be equal to the size of the file.
393 * Writing bytes to this stream will increment the channel's position
394 * accordingly. Changing the channel's position, either explicitly or by
395 * writing, will change this stream's file position.
396 *
397 * @return the file channel associated with this file output stream
398 *
399 * @since 1.4
400 * @spec JSR-51
401 */
402 public FileChannel getChannel() {
403 synchronized (this) {
404 if (channel == null) {
405 channel = FileChannelImpl.open(fd, path, false, true, append, this);
406 }
407 return channel;
408 }
409 }
410
411 /**
412 * Cleans up the connection to the file, and ensures that the
413 * <code>close</code> method of this file output stream is
414 * called when there are no more references to this stream.
415 *
416 * @exception IOException if an I/O error occurs.
417 * @see java.io.FileInputStream#close()
418 */
419 protected void finalize() throws IOException {
420 if (fd != null) {
421 if (fd == FileDescriptor.out || fd == FileDescriptor.err) {
422 flush();
423 } else {
424 /* if fd is shared, the references in FileDescriptor
425 * will ensure that finalizer is only called when
426 * safe to do so. All references using the fd have
427 * become unreachable. We can call close()
428 */
429 close();
430 }
431 }
432 }
433
434 private native void close0() throws IOException;
435
436 private static native void initIDs();
437
438 static {
439 initIDs();
440 }
441
442 }