Java in a Nutshell, 5th Edition [Electronic resources] نسخه متنی

A
FileLock object is returned by the lock(
) and tryLock( ) methods of
FileChannel and represents a lock on a file or a
region of a file. See FileChannel for more
information on file locking with those methods. When a lock is no
longer required, it should be released with the release(
) method. A lock will also be released if the channel is
closed, or when the virtual machine terminates. isValid(
) returns
TRue if the lock has not yet been released, and
returns false if it has been released.

The channel( )
, position( ),
size( ) and isShared( ) methods
return basic information about the lock: the
FileChannel that was locked, the region of the
file that was locked, and whether the lock is shared or exclusive. If
the entire file is locked, then the size( ) method
returns a value (Long.MAX_VALUE) that is much
greater than the actual file size. If the underlying operating system
does not support shared locks, then isShared( )
may return false even if a shared lock was requested.
overlaps( ) is a convenience method that returns
true if the position and size of this lock overlap
the specified position and size.

public abstract class

FileLock {
// Protected Constructors
protected

FileLock (FileChannel

channel , long

position , long

size ,
boolean

shared );
// Public Instance Methods
public final FileChannel

channel ( );
public final boolean

isShared ( );
public abstract boolean

isValid ( );
public final boolean

overlaps (long

position , long

size );
public final long

position ( );
public abstract void

release ( ) throws java.io.IOException;
public final long

size ( );
// Public Methods Overriding Object
public final String

toString ( );
}

Returned By

FileChannel.{lock( ), tryLock(
)}