Source for java.nio.channels.FileChannel

   1: /* FileChannel.java --
   2:    Copyright (C) 2002 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: package java.nio.channels;
  39: 
  40: import java.io.IOException;
  41: import java.nio.ByteBuffer;
  42: import java.nio.MappedByteBuffer;
  43: import java.nio.channels.spi.AbstractInterruptibleChannel;
  44: 
  45: 
  46: /**
  47:  * @author Michael Koch
  48:  * @since 1.4
  49:  */
  50: public abstract class FileChannel extends AbstractInterruptibleChannel
  51:   implements ByteChannel, GatheringByteChannel, ScatteringByteChannel
  52: {
  53:   public static class MapMode
  54:   {
  55:     int m;
  56:     public static final MapMode READ_ONLY = new MapMode(0);
  57:     public static final MapMode READ_WRITE = new MapMode(1);
  58:     public static final MapMode PRIVATE = new MapMode(2);
  59: 
  60:     /**
  61:      * Initializes the MapMode.
  62:      */
  63:     MapMode(int a)
  64:     {
  65:       m = a;
  66:     }
  67: 
  68:     /**
  69:      * Returns a string representation of the <code>MapMode</code> object.
  70:      */
  71:     public String toString()
  72:     {
  73:       if (this == READ_ONLY)
  74:     return "READ_ONLY";
  75:       else if (this == READ_WRITE)
  76:     return "READ_WRITE";
  77: 
  78:       return "PRIVATE";
  79:     }
  80:   }
  81: 
  82:   /**
  83:    * Initializes the channel.
  84:    */
  85:   protected FileChannel()
  86:   {
  87:   }
  88: 
  89:   /**
  90:    * Maps the file into the memory.
  91:    *
  92:    * @exception IllegalArgumentException If the preconditions on the parameters
  93:    * do not hold.
  94:    * @exception IOException If an I/O error occurs.
  95:    * @exception NonReadableChannelException If mode is READ_ONLY but this channel was
  96:    * not opened for reading.
  97:    * @exception NonWritableChannelException If mode is READ_WRITE or PRIVATE but this
  98:    * channel was not opened for writing.
  99:    */
 100:   public abstract MappedByteBuffer map(MapMode mode, long position, long size)
 101:     throws IOException;
 102: 
 103:   /**
 104:    * Return the size of the file thus far
 105:    *
 106:    * @exception ClosedChannelException If this channel is closed.
 107:    */
 108:   public abstract long size() throws IOException;
 109: 
 110:   /**
 111:    * Writes data to the channel.
 112:    *
 113:    * @exception IOException If an I/O error occurs.
 114:    */
 115:   public final long write(ByteBuffer[] srcs) throws IOException
 116:   {
 117:     long result = 0;
 118: 
 119:     for (int i = 0; i < srcs.length; i++)
 120:       result += write(srcs[i]);
 121: 
 122:     return result;
 123:   }
 124: 
 125:   /**
 126:    * Writes data to the channel.
 127:    *
 128:    * @exception IOException If an I/O error occurs.
 129:    */
 130:   public abstract int write(ByteBuffer src) throws IOException;
 131: 
 132:   /**
 133:    * Writes data to the channel.
 134:    *
 135:    * @exception AsynchronousCloseException If another thread closes this channel
 136:    * while the transfer is in progress.
 137:    * @exception ClosedByInterruptException If another thread interrupts the
 138:    * current thread while the transfer is in progress, thereby closing both
 139:    * channels and setting the current thread's interrupt status.
 140:    * @exception ClosedChannelException If this channel is closed.
 141:    * @exception IllegalArgumentException If position is negative.
 142:    * @exception IOException If an I/O error occurs.
 143:    * @exception NonWritableChannelException If this channel was not opened for
 144:    * writing.
 145:    */
 146:   public abstract int write(ByteBuffer srcs, long position)
 147:     throws IOException;
 148: 
 149:   /**
 150:    * Writes data to the channel.
 151:    *
 152:    * @exception IOException If an I/O error occurs.
 153:    */
 154:   public abstract long write(ByteBuffer[] srcs, int offset, int length)
 155:     throws IOException;
 156: 
 157:   /**
 158:    * Reads data from the channel.
 159:    *
 160:    * @exception IOException If an I/O error occurs.
 161:    */
 162:   public abstract long read(ByteBuffer[] dsts, int offset, int length)
 163:     throws IOException;
 164: 
 165:   /**
 166:    * Reads data from the channel.
 167:    *
 168:    * @exception IOException If an I/O error occurs.
 169:    */
 170:   public final long read(ByteBuffer[] dsts) throws IOException
 171:   {
 172:     long result = 0;
 173: 
 174:     for (int i = 0; i < dsts.length; i++)
 175:       read(dsts[i]);
 176: 
 177:     return result;
 178:   }
 179: 
 180:   /**
 181:    * Reads data from the channel.
 182:    *
 183:    * @exception IOException If an I/O error occurs.
 184:    */
 185:   public abstract int read(ByteBuffer dst) throws IOException;
 186: 
 187:   /**
 188:    * Reads data from the channel.
 189:    *
 190:    * @exception AsynchronousCloseException If another thread closes this channel
 191:    * while the transfer is in progress.
 192:    * @exception ClosedByInterruptException If another thread interrupts the
 193:    * current thread while the transfer is in progress, thereby closing both
 194:    * channels and setting the current thread's interrupt status.
 195:    * @exception ClosedChannelException If this channel is closed.
 196:    * @exception IllegalArgumentException If position is negative.
 197:    * @exception IOException If an I/O error occurs.
 198:    * @exception NonReadableChannelException If this channel was not opened for
 199:    * reading.
 200:    */
 201:   public abstract int read(ByteBuffer dst, long position)
 202:     throws IOException;
 203: 
 204:   /**
 205:    * Closes the channel.
 206:    *
 207:    * This is called from @see close.
 208:    *
 209:    * @exception IOException If an I/O error occurs.
 210:    */
 211:   protected abstract void implCloseChannel() throws IOException;
 212: 
 213:   /**
 214:    * msync with the disk
 215:    *
 216:    * @exception ClosedChannelException If this channel is closed.
 217:    * @exception IOException If an I/O error occurs.
 218:    */
 219:   public abstract void force(boolean metaData) throws IOException;
 220: 
 221:   /**
 222:    * Creates a file lock for the whole assoziated file.
 223:    *
 224:    * @exception AsynchronousCloseException If another thread closes this channel
 225:    * while the transfer is in progress.
 226:    * @exception ClosedChannelException If this channel is closed.
 227:    * @exception FileLockInterruptionException If the invoking thread is
 228:    * interrupted while blocked in this method.
 229:    * @exception IOException If an I/O error occurs.
 230:    * @exception NonReadableChannelException If shared is true and this channel
 231:    * was not opened for reading.
 232:    * @exception NonWritableChannelException If shared is false and this channel
 233:    * was not opened for writing.
 234:    * @exception OverlappingFileLockException If a lock that overlaps the
 235:    * requested region is already held by this Java virtual machine, or if
 236:    * another thread is already blocked in this method and is attempting to lock
 237:    * an overlapping region.
 238:    */
 239:   public final FileLock lock() throws IOException
 240:   {
 241:     return lock(0, Long.MAX_VALUE, false);
 242:   }
 243: 
 244:   /**
 245:    * Creates a file lock for a region of the assoziated file.
 246:    *
 247:    * @exception AsynchronousCloseException If another thread closes this channel
 248:    * while the transfer is in progress.
 249:    * @exception ClosedChannelException If this channel is closed.
 250:    * @exception FileLockInterruptionException If the invoking thread is
 251:    * interrupted while blocked in this method.
 252:    * @exception IllegalArgumentException If the preconditions on the parameters
 253:    * do not hold.
 254:    * @exception IOException If an I/O error occurs.
 255:    * @exception OverlappingFileLockException If a lock that overlaps the
 256:    * requested region is already held by this Java virtual machine, or if
 257:    * another thread is already blocked in this method and is attempting to lock
 258:    * an overlapping region.
 259:    * @exception NonReadableChannelException If shared is true and this channel
 260:    * was not opened for reading.
 261:    * @exception NonWritableChannelException If shared is false and this channel
 262:    * was not opened for writing.
 263:    */
 264:   public abstract FileLock lock(long position, long size, boolean shared)
 265:     throws IOException;
 266: 
 267:   /**
 268:    * Tries to aqquire alock on the whole assoziated file.
 269:    *
 270:    * @exception ClosedChannelException If this channel is closed.
 271:    * @exception IOException If an I/O error occurs.
 272:    * @exception OverlappingFileLockException If a lock that overlaps the
 273:    * requested region is already held by this Java virtual machine, or if
 274:    * another thread is already blocked in this method and is attempting to lock
 275:    * an overlapping region.
 276:    */
 277:   public final FileLock tryLock() throws IOException
 278:   {
 279:     return tryLock(0, Long.MAX_VALUE, false);
 280:   }
 281: 
 282:   /**
 283:    * Tries to aqquire a lock on a region of the assoziated file.
 284:    *
 285:    * @exception ClosedChannelException If this channel is closed.
 286:    * @exception IllegalArgumentException If the preconditions on the parameters
 287:    * do not hold.
 288:    * @exception IOException If an I/O error occurs.
 289:    * @exception OverlappingFileLockException If a lock that overlaps the
 290:    * requested region is already held by this Java virtual machine, or if
 291:    * another thread is already blocked in this method and is attempting to lock
 292:    * an overlapping region.
 293:    */
 294:   public abstract FileLock tryLock(long position, long size, boolean shared)
 295:     throws IOException;
 296: 
 297:   /**
 298:    * Returns the current position on the file.
 299:    *
 300:    * @exception ClosedChannelException If this channel is closed.
 301:    * @exception IOException If an I/O error occurs.
 302:    */
 303:   public abstract long position() throws IOException;
 304: 
 305:   /**
 306:    * Sets the position of the channel on the assoziated file.
 307:    *
 308:    * @exception ClosedChannelException If this channel is closed.
 309:    * @exception IllegalArgumentException If newPosition is negative.
 310:    * @exception IOException If an I/O error occurs.
 311:    */
 312:   public abstract FileChannel position(long newPosition)
 313:     throws IOException;
 314: 
 315:   /**
 316:    * Transfers bytes from this channel's file to the given writable byte
 317:    * channel.
 318:    *
 319:    * @exception AsynchronousCloseException If another thread closes this channel
 320:    * while the transfer is in progress.
 321:    * @exception ClosedByInterruptException If another thread interrupts the
 322:    * current thread while the transfer is in progress, thereby closing both
 323:    * channels and setting the current thread's interrupt status.
 324:    * @exception ClosedChannelException If this channel is closed.
 325:    * @exception IllegalArgumentException If the preconditions on the parameters
 326:    * do not hold.
 327:    * @exception IOException If an I/O error occurs.
 328:    * @exception NonReadableChannelException If this channel was not opened for
 329:    * reading.
 330:    * @exception NonWritableChannelException If the target channel was not
 331:    * opened for writing.
 332:    */
 333:   public abstract long transferTo(long position, long count,
 334:                                   WritableByteChannel target)
 335:     throws IOException;
 336: 
 337:   /**
 338:    * Transfers bytes from the given readable channel into this channel.
 339:    *
 340:    * @exception AsynchronousCloseException If another thread closes this channel
 341:    * while the transfer is in progress.
 342:    * @exception ClosedByInterruptException If another thread interrupts the
 343:    * current thread while the transfer is in progress, thereby closing both
 344:    * channels and setting the current thread's interrupt status.
 345:    * @exception ClosedChannelException If this channel is closed.
 346:    * @exception IllegalArgumentException If the preconditions on the parameters
 347:    * do not hold.
 348:    * @exception IOException If an I/O error occurs.
 349:    * @exception NonReadableChannelException If the source channel was not
 350:    * opened for reading.
 351:    * @exception NonWritableChannelException If this channel was not opened for
 352:    * writing.
 353:    */
 354:   public abstract long transferFrom(ReadableByteChannel src, long position,
 355:                                     long count) throws IOException;
 356: 
 357:   /**
 358:    * Truncates the channel's file at <code>size</code>.
 359:    *
 360:    * @exception ClosedChannelException If this channel is closed.
 361:    * @exception IllegalArgumentException If size is negative.
 362:    * @exception IOException If an I/O error occurs.
 363:    * @exception NonWritableChannelException If this channel was not opened for
 364:    * writing.
 365:    */
 366:   public abstract FileChannel truncate(long size) throws IOException;
 367: }