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