java.nio.channels

Class FileChannel

java.lang.Object

java.nio.channels.spi.AbstractInterruptibleChannel

java.nio.channels.FileChannel

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, ByteChannel, Channel, GatheringByteChannel, InterruptibleChannel, ReadableByteChannel, ScatteringByteChannel, WritableByteChannel

public abstract class FileChannel
extends java.nio.channels.spi.AbstractInterruptibleChannel
implements ByteChannel, GatheringByteChannel, ScatteringByteChannel

Since:

1.4

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FileChannel.MapMode

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	FileChannel() Initializes the channel.

Method Summary

Methods

Modifier and Type	Method and Description
abstract void	force(boolean metaData) msync with the disk
protected abstract void	implCloseChannel() Closes the channel.
FileLock	lock() Creates a file lock for the whole associated file.
abstract FileLock	lock(long position, long size, boolean shared) Creates a file lock for a region of the associated file.
abstract java.nio.MappedByteBuffer	map(FileChannel.MapMode mode, long position, long size) Maps the file into the memory.
abstract long	position() Returns the current position on the file.
abstract FileChannel	position(long newPosition) Sets the position of the channel on the assoziated file.
abstract int	read(java.nio.ByteBuffer dst) Reads data from the channel.
long	read(java.nio.ByteBuffer[] dsts) Reads data from the channel.
abstract long	read(java.nio.ByteBuffer[] dsts, int offset, int length) Reads data from the channel.
abstract int	read(java.nio.ByteBuffer dst, long position) Reads data from the channel.
abstract long	size() Return the size of the file thus far
abstract long	transferFrom(ReadableByteChannel src, long position, long count) Transfers bytes from the given readable channel into this channel.
abstract long	transferTo(long position, long count, WritableByteChannel target) Transfers bytes from this channel's file to the given writable byte channel.
abstract FileChannel	truncate(long size) Truncates the channel's file at size.
FileLock	tryLock() Tries to aqquire alock on the whole associated file.
abstract FileLock	tryLock(long position, long size, boolean shared) Tries to aqquire a lock on a region of the associated file.
abstract int	write(java.nio.ByteBuffer src) Writes data to the channel.
long	write(java.nio.ByteBuffer[] srcs) Writes data to the channel.
abstract long	write(java.nio.ByteBuffer[] srcs, int offset, int length) Writes data to the channel.
abstract int	write(java.nio.ByteBuffer srcs, long position) Writes data to the channel.

Methods inherited from class java.nio.channels.spi.AbstractInterruptibleChannel

begin, close, end, isOpen

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.nio.channels.Channel

close, isOpen

Constructor Detail

FileChannel

protected FileChannel()

Initializes the channel.

Method Detail

map

public abstract java.nio.MappedByteBuffer map(FileChannel.MapMode mode,
                            long position,
                            long size)
                                       throws java.io.IOException

Maps the file into the memory.

Throws:

java.lang.IllegalArgumentException - If the preconditions on the parameters do not hold.

java.io.IOException - If an I/O error occurs.

NonReadableChannelException - If mode is READ_ONLY but this channel was not opened for reading.

NonWritableChannelException - If mode is READ_WRITE or PRIVATE but this channel was not opened for writing.

size

public abstract long size()
                   throws java.io.IOException

Return the size of the file thus far

Throws:

ClosedChannelException - If this channel is closed.

java.io.IOException

write

public final long write(java.nio.ByteBuffer[] srcs)
                 throws java.io.IOException

Writes data to the channel.

Specified by:

write in interface GatheringByteChannel

Throws:

java.io.IOException - If an I/O error occurs.

write

public abstract int write(java.nio.ByteBuffer src)
                   throws java.io.IOException

Writes data to the channel.

Specified by:

write in interface WritableByteChannel

Throws:

java.io.IOException - If an I/O error occurs.

write

public abstract int write(java.nio.ByteBuffer srcs,
        long position)
                   throws java.io.IOException

Writes data to the channel.

Throws:

AsynchronousCloseException - If another thread closes this channel while the transfer is in progress.

ClosedByInterruptException - If another thread interrupts the current thread while the transfer is in progress, thereby closing both channels and setting the current thread's interrupt status.

ClosedChannelException - If this channel is closed.

java.lang.IllegalArgumentException - If position is negative.

java.io.IOException - If an I/O error occurs.

NonWritableChannelException - If this channel was not opened for writing.

write

public abstract long write(java.nio.ByteBuffer[] srcs,
         int offset,
         int length)
                    throws java.io.IOException

Writes data to the channel.

Specified by:

write in interface GatheringByteChannel

Throws:

java.io.IOException - If an I/O error occurs.

read

public abstract long read(java.nio.ByteBuffer[] dsts,
        int offset,
        int length)
                   throws java.io.IOException

Reads data from the channel.

Specified by:

read in interface ScatteringByteChannel

Throws:

java.io.IOException - If an I/O error occurs.

read

public final long read(java.nio.ByteBuffer[] dsts)
                throws java.io.IOException

Reads data from the channel.

Specified by:

read in interface ScatteringByteChannel

Throws:

java.io.IOException - If an I/O error occurs.

read

public abstract int read(java.nio.ByteBuffer dst)
                  throws java.io.IOException

Reads data from the channel.

Specified by:

read in interface ReadableByteChannel

Parameters:

dst - the buffer to put the read data into

Returns:

the numer of bytes read

Throws:

java.io.IOException - If an I/O error occurs.

read

public abstract int read(java.nio.ByteBuffer dst,
       long position)
                  throws java.io.IOException

Reads data from the channel.

Throws:

AsynchronousCloseException - If another thread closes this channel while the transfer is in progress.

ClosedByInterruptException - If another thread interrupts the current thread while the transfer is in progress, thereby closing both channels and setting the current thread's interrupt status.

ClosedChannelException - If this channel is closed.

java.lang.IllegalArgumentException - If position is negative.

java.io.IOException - If an I/O error occurs.

NonReadableChannelException - If this channel was not opened for reading.

implCloseChannel

protected abstract void implCloseChannel()
                                  throws java.io.IOException

Closes the channel. This is called from @see close.

Specified by:

implCloseChannel in class java.nio.channels.spi.AbstractInterruptibleChannel

Throws:

java.io.IOException - If an I/O error occurs.

force

public abstract void force(boolean metaData)
                    throws java.io.IOException

msync with the disk

Throws:

ClosedChannelException - If this channel is closed.

java.io.IOException - If an I/O error occurs.

lock

public final FileLock lock()
                    throws java.io.IOException

Creates a file lock for the whole associated file.

Throws:

AsynchronousCloseException - If another thread closes this channel while the transfer is in progress.

ClosedChannelException - If this channel is closed.

FileLockInterruptionException - If the invoking thread is interrupted while blocked in this method.

java.io.IOException - If an I/O error occurs.

NonReadableChannelException - If shared is true and this channel was not opened for reading.

NonWritableChannelException - If shared is false and this channel was not opened for writing.

OverlappingFileLockException - If a lock that overlaps the requested region is already held by this Java virtual machine, or if another thread is already blocked in this method and is attempting to lock an overlapping region.

lock

public abstract FileLock lock(long position,
            long size,
            boolean shared)
                       throws java.io.IOException

Creates a file lock for a region of the associated file.

Throws:

AsynchronousCloseException - If another thread closes this channel while the transfer is in progress.

ClosedChannelException - If this channel is closed.

FileLockInterruptionException - If the invoking thread is interrupted while blocked in this method.

java.lang.IllegalArgumentException - If the preconditions on the parameters do not hold.

java.io.IOException - If an I/O error occurs.

OverlappingFileLockException - If a lock that overlaps the requested region is already held by this Java virtual machine, or if another thread is already blocked in this method and is attempting to lock an overlapping region.

NonReadableChannelException - If shared is true and this channel was not opened for reading.

NonWritableChannelException - If shared is false and this channel was not opened for writing.

tryLock

public final FileLock tryLock()
                       throws java.io.IOException

Tries to aqquire alock on the whole associated file.

Throws:

ClosedChannelException - If this channel is closed.

java.io.IOException - If an I/O error occurs.

OverlappingFileLockException - If a lock that overlaps the requested region is already held by this Java virtual machine, or if another thread is already blocked in this method and is attempting to lock an overlapping region.

tryLock

public abstract FileLock tryLock(long position,
               long size,
               boolean shared)
                          throws java.io.IOException

Tries to aqquire a lock on a region of the associated file.

Throws:

ClosedChannelException - If this channel is closed.

java.lang.IllegalArgumentException - If the preconditions on the parameters do not hold.

java.io.IOException - If an I/O error occurs.

OverlappingFileLockException - If a lock that overlaps the requested region is already held by this Java virtual machine, or if another thread is already blocked in this method and is attempting to lock an overlapping region.

position

public abstract long position()
                       throws java.io.IOException

Returns the current position on the file.

Throws:

ClosedChannelException - If this channel is closed.

java.io.IOException - If an I/O error occurs.

position

public abstract FileChannel position(long newPosition)
                              throws java.io.IOException

Sets the position of the channel on the assoziated file.

Throws:

ClosedChannelException - If this channel is closed.

java.lang.IllegalArgumentException - If newPosition is negative.

java.io.IOException - If an I/O error occurs.

transferTo

public abstract long transferTo(long position,
              long count,
              WritableByteChannel target)
                         throws java.io.IOException

Transfers bytes from this channel's file to the given writable byte channel.

Throws:

AsynchronousCloseException - If another thread closes this channel while the transfer is in progress.

ClosedByInterruptException - If another thread interrupts the current thread while the transfer is in progress, thereby closing both channels and setting the current thread's interrupt status.

ClosedChannelException - If this channel is closed.

java.lang.IllegalArgumentException - If the preconditions on the parameters do not hold.

java.io.IOException - If an I/O error occurs.

NonReadableChannelException - If this channel was not opened for reading.

NonWritableChannelException - If the target channel was not opened for writing.

transferFrom

public abstract long transferFrom(ReadableByteChannel src,
                long position,
                long count)
                           throws java.io.IOException

Transfers bytes from the given readable channel into this channel.

Throws:

AsynchronousCloseException - If another thread closes this channel while the transfer is in progress.

ClosedByInterruptException - If another thread interrupts the current thread while the transfer is in progress, thereby closing both channels and setting the current thread's interrupt status.

ClosedChannelException - If this channel is closed.

java.lang.IllegalArgumentException - If the preconditions on the parameters do not hold.

java.io.IOException - If an I/O error occurs.

NonReadableChannelException - If the source channel was not opened for reading.

NonWritableChannelException - If this channel was not opened for writing.

truncate

public abstract FileChannel truncate(long size)
                              throws java.io.IOException

Truncates the channel's file at size.

Throws:

ClosedChannelException - If this channel is closed.

java.lang.IllegalArgumentException - If size is negative.

java.io.IOException - If an I/O error occurs.

NonWritableChannelException - If this channel was not opened for writing.