39 * <code>FileReader</code>.
40 *
41 * @author Arthur van Hoff
42 * @see java.io.File
43 * @see java.io.FileDescriptor
44 * @see java.io.FileOutputStream
45 * @see java.nio.file.Files#newInputStream
46 * @since JDK1.0
47 */
48 public
49 class FileInputStream extends InputStream
50 {
51 /* File Descriptor - handle to the open file */
52 private final FileDescriptor fd;
53
54 private FileChannel channel = null;
55
56 private final Object closeLock = new Object();
57 private volatile boolean closed = false;
58
59 /**
60 * Creates a <code>FileInputStream</code> by
61 * opening a connection to an actual file,
62 * the file named by the path name <code>name</code>
63 * in the file system. A new <code>FileDescriptor</code>
64 * object is created to represent this file
65 * connection.
66 * <p>
67 * First, if there is a security
68 * manager, its <code>checkRead</code> method
69 * is called with the <code>name</code> argument
70 * as its argument.
71 * <p>
72 * If the named file does not exist, is a directory rather than a regular
73 * file, or for some other reason cannot be opened for reading then a
74 * <code>FileNotFoundException</code> is thrown.
75 *
76 * @param name the system-dependent file name.
77 * @exception FileNotFoundException if the file does not exist,
78 * is a directory rather than a regular file,
107 * @param file the file to be opened for reading.
108 * @exception FileNotFoundException if the file does not exist,
109 * is a directory rather than a regular file,
110 * or for some other reason cannot be opened for
111 * reading.
112 * @exception SecurityException if a security manager exists and its
113 * <code>checkRead</code> method denies read access to the file.
114 * @see java.io.File#getPath()
115 * @see java.lang.SecurityManager#checkRead(java.lang.String)
116 */
117 public FileInputStream(File file) throws FileNotFoundException {
118 String name = (file != null ? file.getPath() : null);
119 SecurityManager security = System.getSecurityManager();
120 if (security != null) {
121 security.checkRead(name);
122 }
123 if (name == null) {
124 throw new NullPointerException();
125 }
126 fd = new FileDescriptor();
127 fd.attach(this);
128 open(name);
129 }
130
131 /**
132 * Creates a <code>FileInputStream</code> by using the file descriptor
133 * <code>fdObj</code>, which represents an existing connection to an
134 * actual file in the file system.
135 * <p>
136 * If there is a security manager, its <code>checkRead</code> method is
137 * called with the file descriptor <code>fdObj</code> as its argument to
138 * see if it's ok to read the file descriptor. If read access is denied
139 * to the file descriptor a <code>SecurityException</code> is thrown.
140 * <p>
141 * If <code>fdObj</code> is null then a <code>NullPointerException</code>
142 * is thrown.
143 * <p>
144 * This constructor does not throw an exception if <code>fdObj</code>
145 * is {@link java.io.FileDescriptor#valid() invalid}.
146 * However, if the methods are invoked on the resulting stream to attempt
147 * I/O on the stream, an <code>IOException</code> is thrown.
148 *
149 * @param fdObj the file descriptor to be opened for reading.
150 * @throws SecurityException if a security manager exists and its
151 * <code>checkRead</code> method denies read access to the
152 * file descriptor.
153 * @see SecurityManager#checkRead(java.io.FileDescriptor)
154 */
155 public FileInputStream(FileDescriptor fdObj) {
156 SecurityManager security = System.getSecurityManager();
157 if (fdObj == null) {
158 throw new NullPointerException();
159 }
160 if (security != null) {
161 security.checkRead(fdObj);
162 }
163 fd = fdObj;
164
165 /*
166 * FileDescriptor is being shared by streams.
167 * Register this stream with FileDescriptor tracker.
168 */
169 fd.attach(this);
170 }
171
172 /**
173 * Opens the specified file for reading.
174 * @param name the name of the file
175 */
176 private native void open(String name) throws FileNotFoundException;
177
178 /**
179 * Reads a byte of data from this input stream. This method blocks
180 * if no input is yet available.
181 *
182 * @return the next byte of data, or <code>-1</code> if the end of the
183 * file is reached.
184 * @exception IOException if an I/O error occurs.
185 */
186 public native int read() throws IOException;
187
188 /**
189 * Reads a subarray as a sequence of bytes.
276 /**
277 * Closes this file input stream and releases any system resources
278 * associated with the stream.
279 *
280 * <p> If this stream has an associated channel then the channel is closed
281 * as well.
282 *
283 * @exception IOException if an I/O error occurs.
284 *
285 * @revised 1.4
286 * @spec JSR-51
287 */
288 public void close() throws IOException {
289 synchronized (closeLock) {
290 if (closed) {
291 return;
292 }
293 closed = true;
294 }
295 if (channel != null) {
296 channel.close();
297 }
298 fd.closeAll(new Closeable() {
299 public void close() throws IOException {
300 close0();
301 }
302 });
303 }
304
305 /**
306 * Returns the <code>FileDescriptor</code>
307 * object that represents the connection to
308 * the actual file in the file system being
309 * used by this <code>FileInputStream</code>.
310 *
311 * @return the file descriptor object associated with this stream.
312 * @exception IOException if an I/O error occurs.
313 * @see java.io.FileDescriptor
314 */
315 public final FileDescriptor getFD() throws IOException {
316 if (fd != null) {
317 return fd;
318 }
319 throw new IOException();
320 }
321
322 /**
323 * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
324 * object associated with this file input stream.
325 *
326 * <p> The initial {@link java.nio.channels.FileChannel#position()
327 * </code>position<code>} of the returned channel will be equal to the
328 * number of bytes read from the file so far. Reading bytes from this
329 * stream will increment the channel's position. Changing the channel's
330 * position, either explicitly or by reading, will change this stream's
331 * file position.
332 *
333 * @return the file channel associated with this file input stream
334 *
335 * @since 1.4
336 * @spec JSR-51
337 */
338 public FileChannel getChannel() {
339 synchronized (this) {
340 if (channel == null) {
341 channel = FileChannelImpl.open(fd, true, false, this);
342 }
343 return channel;
344 }
345 }
346
347 private static native void initIDs();
348
349 private native void close0() throws IOException;
350
351 static {
352 initIDs();
353 }
354
355 /**
356 * Ensures that the <code>close</code> method of this file input stream is
357 * called when there are no more references to it.
358 *
359 * @exception IOException if an I/O error occurs.
360 * @see java.io.FileInputStream#close()
361 */
362 protected void finalize() throws IOException {
363 if ((fd != null) && (fd != FileDescriptor.in)) {
364 /* if fd is shared, the references in FileDescriptor
365 * will ensure that finalizer is only called when
366 * safe to do so. All references using the fd have
367 * become unreachable. We can call close()
368 */
369 close();
370 }
371 }
372 }
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39 * <code>FileReader</code>.
40 *
41 * @author Arthur van Hoff
42 * @see java.io.File
43 * @see java.io.FileDescriptor
44 * @see java.io.FileOutputStream
45 * @see java.nio.file.Files#newInputStream
46 * @since JDK1.0
47 */
48 public
49 class FileInputStream extends InputStream
50 {
51 /* File Descriptor - handle to the open file */
52 private final FileDescriptor fd;
53
54 private FileChannel channel = null;
55
56 private final Object closeLock = new Object();
57 private volatile boolean closed = false;
58
59 private static final ThreadLocal<Boolean> runningFinalize =
60 new ThreadLocal<>();
61
62 private static boolean isRunningFinalize() {
63 Boolean val;
64 if ((val = runningFinalize.get()) != null)
65 return val.booleanValue();
66 return false;
67 }
68
69 /**
70 * Creates a <code>FileInputStream</code> by
71 * opening a connection to an actual file,
72 * the file named by the path name <code>name</code>
73 * in the file system. A new <code>FileDescriptor</code>
74 * object is created to represent this file
75 * connection.
76 * <p>
77 * First, if there is a security
78 * manager, its <code>checkRead</code> method
79 * is called with the <code>name</code> argument
80 * as its argument.
81 * <p>
82 * If the named file does not exist, is a directory rather than a regular
83 * file, or for some other reason cannot be opened for reading then a
84 * <code>FileNotFoundException</code> is thrown.
85 *
86 * @param name the system-dependent file name.
87 * @exception FileNotFoundException if the file does not exist,
88 * is a directory rather than a regular file,
117 * @param file the file to be opened for reading.
118 * @exception FileNotFoundException if the file does not exist,
119 * is a directory rather than a regular file,
120 * or for some other reason cannot be opened for
121 * reading.
122 * @exception SecurityException if a security manager exists and its
123 * <code>checkRead</code> method denies read access to the file.
124 * @see java.io.File#getPath()
125 * @see java.lang.SecurityManager#checkRead(java.lang.String)
126 */
127 public FileInputStream(File file) throws FileNotFoundException {
128 String name = (file != null ? file.getPath() : null);
129 SecurityManager security = System.getSecurityManager();
130 if (security != null) {
131 security.checkRead(name);
132 }
133 if (name == null) {
134 throw new NullPointerException();
135 }
136 fd = new FileDescriptor();
137 fd.incrementAndGetUseCount();
138 open(name);
139 }
140
141 /**
142 * Creates a <code>FileInputStream</code> by using the file descriptor
143 * <code>fdObj</code>, which represents an existing connection to an
144 * actual file in the file system.
145 * <p>
146 * If there is a security manager, its <code>checkRead</code> method is
147 * called with the file descriptor <code>fdObj</code> as its argument to
148 * see if it's ok to read the file descriptor. If read access is denied
149 * to the file descriptor a <code>SecurityException</code> is thrown.
150 * <p>
151 * If <code>fdObj</code> is null then a <code>NullPointerException</code>
152 * is thrown.
153 * <p>
154 * This constructor does not throw an exception if <code>fdObj</code>
155 * is {@link java.io.FileDescriptor#valid() invalid}.
156 * However, if the methods are invoked on the resulting stream to attempt
157 * I/O on the stream, an <code>IOException</code> is thrown.
158 *
159 * @param fdObj the file descriptor to be opened for reading.
160 * @throws SecurityException if a security manager exists and its
161 * <code>checkRead</code> method denies read access to the
162 * file descriptor.
163 * @see SecurityManager#checkRead(java.io.FileDescriptor)
164 */
165 public FileInputStream(FileDescriptor fdObj) {
166 SecurityManager security = System.getSecurityManager();
167 if (fdObj == null) {
168 throw new NullPointerException();
169 }
170 if (security != null) {
171 security.checkRead(fdObj);
172 }
173 fd = fdObj;
174
175 /*
176 * FileDescriptor is being shared by streams.
177 * Ensure that it's GC'ed only when all the streams/channels are done
178 * using it.
179 */
180 fd.incrementAndGetUseCount();
181 }
182
183 /**
184 * Opens the specified file for reading.
185 * @param name the name of the file
186 */
187 private native void open(String name) throws FileNotFoundException;
188
189 /**
190 * Reads a byte of data from this input stream. This method blocks
191 * if no input is yet available.
192 *
193 * @return the next byte of data, or <code>-1</code> if the end of the
194 * file is reached.
195 * @exception IOException if an I/O error occurs.
196 */
197 public native int read() throws IOException;
198
199 /**
200 * Reads a subarray as a sequence of bytes.
287 /**
288 * Closes this file input stream and releases any system resources
289 * associated with the stream.
290 *
291 * <p> If this stream has an associated channel then the channel is closed
292 * as well.
293 *
294 * @exception IOException if an I/O error occurs.
295 *
296 * @revised 1.4
297 * @spec JSR-51
298 */
299 public void close() throws IOException {
300 synchronized (closeLock) {
301 if (closed) {
302 return;
303 }
304 closed = true;
305 }
306 if (channel != null) {
307 /*
308 * Decrement the FD use count associated with the channel
309 * The use count is incremented whenever a new channel
310 * is obtained from this stream.
311 */
312 fd.decrementAndGetUseCount();
313 channel.close();
314 }
315
316 /*
317 * Decrement the FD use count associated with this stream
318 */
319 int useCount = fd.decrementAndGetUseCount();
320
321 /*
322 * If FileDescriptor is still in use by another stream, the finalizer
323 * will not close it.
324 */
325 if ((useCount <= 0) || !isRunningFinalize()) {
326 close0();
327 }
328 }
329
330 /**
331 * Returns the <code>FileDescriptor</code>
332 * object that represents the connection to
333 * the actual file in the file system being
334 * used by this <code>FileInputStream</code>.
335 *
336 * @return the file descriptor object associated with this stream.
337 * @exception IOException if an I/O error occurs.
338 * @see java.io.FileDescriptor
339 */
340 public final FileDescriptor getFD() throws IOException {
341 if (fd != null) return fd;
342 throw new IOException();
343 }
344
345 /**
346 * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
347 * object associated with this file input stream.
348 *
349 * <p> The initial {@link java.nio.channels.FileChannel#position()
350 * </code>position<code>} of the returned channel will be equal to the
351 * number of bytes read from the file so far. Reading bytes from this
352 * stream will increment the channel's position. Changing the channel's
353 * position, either explicitly or by reading, will change this stream's
354 * file position.
355 *
356 * @return the file channel associated with this file input stream
357 *
358 * @since 1.4
359 * @spec JSR-51
360 */
361 public FileChannel getChannel() {
362 synchronized (this) {
363 if (channel == null) {
364 channel = FileChannelImpl.open(fd, true, false, this);
365
366 /*
367 * Increment fd's use count. Invoking the channel's close()
368 * method will result in decrementing the use count set for
369 * the channel.
370 */
371 fd.incrementAndGetUseCount();
372 }
373 return channel;
374 }
375 }
376
377 private static native void initIDs();
378
379 private native void close0() throws IOException;
380
381 static {
382 initIDs();
383 }
384
385 /**
386 * Ensures that the <code>close</code> method of this file input stream is
387 * called when there are no more references to it.
388 *
389 * @exception IOException if an I/O error occurs.
390 * @see java.io.FileInputStream#close()
391 */
392 protected void finalize() throws IOException {
393 if ((fd != null) && (fd != FileDescriptor.in)) {
394
395 /*
396 * Finalizer should not release the FileDescriptor if another
397 * stream is still using it. If the user directly invokes
398 * close() then the FileDescriptor is also released.
399 */
400 runningFinalize.set(Boolean.TRUE);
401 try {
402 close();
403 } finally {
404 runningFinalize.set(Boolean.FALSE);
405 }
406 }
407 }
408 }
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