Showing the changes to java/pkg/java/io/FileInputStream.java (1 of 18352 files). Show all
Unified · Split
| @@ -0,0 +1,408 @@ | ||
| 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 | + | |
| 31 | + | |
| 32 | +/** | |
| 33 | + * A <code>FileInputStream</code> obtains input bytes | |
| 34 | + * from a file in a file system. What files | |
| 35 | + * are available depends on the host environment. | |
| 36 | + * | |
| 37 | + * <p><code>FileInputStream</code> is meant for reading streams of raw bytes | |
| 38 | + * such as image data. For reading streams of characters, consider using | |
| 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, | |
| 89 | + * or for some other reason cannot be opened for | |
| 90 | + * reading. | |
| 91 | + * @exception SecurityException if a security manager exists and its | |
| 92 | + * <code>checkRead</code> method denies read access | |
| 93 | + * to the file. | |
| 94 | + * @see java.lang.SecurityManager#checkRead(java.lang.String) | |
| 95 | + */ | |
| 96 | + public FileInputStream(String name) throws FileNotFoundException { | |
| 97 | + this(name != null ? new File(name) : null); | |
| 98 | + } | |
| 99 | + | |
| 100 | + /** | |
| 101 | + * Creates a <code>FileInputStream</code> by | |
| 102 | + * opening a connection to an actual file, | |
| 103 | + * the file named by the <code>File</code> | |
| 104 | + * object <code>file</code> in the file system. | |
| 105 | + * A new <code>FileDescriptor</code> object | |
| 106 | + * is created to represent this file connection. | |
| 107 | + * <p> | |
| 108 | + * First, if there is a security manager, | |
| 109 | + * its <code>checkRead</code> method is called | |
| 110 | + * with the path represented by the <code>file</code> | |
| 111 | + * argument as its argument. | |
| 112 | + * <p> | |
| 113 | + * If the named file does not exist, is a directory rather than a regular | |
| 114 | + * file, or for some other reason cannot be opened for reading then a | |
| 115 | + * <code>FileNotFoundException</code> is thrown. | |
| 116 | + * | |
| 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. | |
| 201 | + * @param b the data to be written | |
| 202 | + * @param off the start offset in the data | |
| 203 | + * @param len the number of bytes that are written | |
| 204 | + * @exception IOException If an I/O error has occurred. | |
| 205 | + */ | |
| 206 | + private native int readBytes(byte b[], int off, int len) throws IOException; | |
| 207 | + | |
| 208 | + /** | |
| 209 | + * Reads up to <code>b.length</code> bytes of data from this input | |
| 210 | + * stream into an array of bytes. This method blocks until some input | |
| 211 | + * is available. | |
| 212 | + * | |
| 213 | + * @param b the buffer into which the data is read. | |
| 214 | + * @return the total number of bytes read into the buffer, or | |
| 215 | + * <code>-1</code> if there is no more data because the end of | |
| 216 | + * the file has been reached. | |
| 217 | + * @exception IOException if an I/O error occurs. | |
| 218 | + */ | |
| 219 | + public int read(byte b[]) throws IOException { | |
| 220 | + return readBytes(b, 0, b.length); | |
| 221 | + } | |
| 222 | + | |
| 223 | + /** | |
| 224 | + * Reads up to <code>len</code> bytes of data from this input stream | |
| 225 | + * into an array of bytes. If <code>len</code> is not zero, the method | |
| 226 | + * blocks until some input is available; otherwise, no | |
| 227 | + * bytes are read and <code>0</code> is returned. | |
| 228 | + * | |
| 229 | + * @param b the buffer into which the data is read. | |
| 230 | + * @param off the start offset in the destination array <code>b</code> | |
| 231 | + * @param len the maximum number of bytes read. | |
| 232 | + * @return the total number of bytes read into the buffer, or | |
| 233 | + * <code>-1</code> if there is no more data because the end of | |
| 234 | + * the file has been reached. | |
| 235 | + * @exception NullPointerException If <code>b</code> is <code>null</code>. | |
| 236 | + * @exception IndexOutOfBoundsException If <code>off</code> is negative, | |
| 237 | + * <code>len</code> is negative, or <code>len</code> is greater than | |
| 238 | + * <code>b.length - off</code> | |
| 239 | + * @exception IOException if an I/O error occurs. | |
| 240 | + */ | |
| 241 | + public int read(byte b[], int off, int len) throws IOException { | |
| 242 | + return readBytes(b, off, len); | |
| 243 | + } | |
| 244 | + | |
| 245 | + /** | |
| 246 | + * Skips over and discards <code>n</code> bytes of data from the | |
| 247 | + * input stream. | |
| 248 | + * | |
| 249 | + * <p>The <code>skip</code> method may, for a variety of | |
| 250 | + * reasons, end up skipping over some smaller number of bytes, | |
| 251 | + * possibly <code>0</code>. If <code>n</code> is negative, an | |
| 252 | + * <code>IOException</code> is thrown, even though the <code>skip</code> | |
| 253 | + * method of the {@link InputStream} superclass does nothing in this case. | |
| 254 | + * The actual number of bytes skipped is returned. | |
| 255 | + * | |
| 256 | + * <p>This method may skip more bytes than are remaining in the backing | |
| 257 | + * file. This produces no exception and the number of bytes skipped | |
| 258 | + * may include some number of bytes that were beyond the EOF of the | |
| 259 | + * backing file. Attempting to read from the stream after skipping past | |
| 260 | + * the end will result in -1 indicating the end of the file. | |
| 261 | + * | |
| 262 | + * @param n the number of bytes to be skipped. | |
| 263 | + * @return the actual number of bytes skipped. | |
| 264 | + * @exception IOException if n is negative, if the stream does not | |
| 265 | + * support seek, or if an I/O error occurs. | |
| 266 | + */ | |
| 267 | + public native long skip(long n) throws IOException; | |
| 268 | + | |
| 269 | + /** | |
| 270 | + * Returns an estimate of the number of remaining bytes that can be read (or | |
| 271 | + * skipped over) from this input stream without blocking by the next | |
| 272 | + * invocation of a method for this input stream. The next invocation might be | |
| 273 | + * the same thread or another thread. A single read or skip of this | |
| 274 | + * many bytes will not block, but may read or skip fewer bytes. | |
| 275 | + * | |
| 276 | + * <p> In some cases, a non-blocking read (or skip) may appear to be | |
| 277 | + * blocked when it is merely slow, for example when reading large | |
| 278 | + * files over slow networks. | |
| 279 | + * | |
| 280 | + * @return an estimate of the number of remaining bytes that can be read | |
| 281 | + * (or skipped over) from this input stream without blocking. | |
| 282 | + * @exception IOException if this file input stream has been closed by calling | |
| 283 | + * {@code close} or an I/O error occurs. | |
| 284 | + */ | |
| 285 | + public native int available() throws IOException; | |
| 286 | + | |
| 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 | +} | |