uk.ac.starlink.table.storage

Class FileByteStore

java.lang.Object

uk.ac.starlink.table.storage.FileByteStore

All Implemented Interfaces:

ByteStore

public class FileByteStore
extends Object
implements ByteStore

ByteStore implementation which uses a temporary file.

Since:

11 Jul 2008

Author:

Mark Taylor

Constructor Summary

Constructors

Constructor and Description
FileByteStore() Constructs a new FileByteStore which uses a temporary file as backing store.
FileByteStore(File file) Constructs a new FileByteStore which uses the given file as a backing store.

Method Summary

Modifier and Type	Method and Description
void	close() Tidies up.
static void	copy(File file, OutputStream out) Utility method to copy the contents of a file to an output stream.
void	copy(OutputStream out) Takes all the data written so far into this store's sink stream and copies it to a destination stream.
File	getFile() Returns the file used by this store.
long	getLength() Returns the number of bytes currently stored in this object.
OutputStream	getOutputStream() Returns an output stream which can be used to write to the store.
ByteBuffer[]	toByteBuffers() Returns an array of byte buffers containing the bytes written to this store.
static ByteBuffer[]	toByteBuffers(File file) Returns a read-only ByteBuffer array representing the contents of a file, with default maximum buffer length.

Methods inherited from class java.lang.Object

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

Constructor Detail

FileByteStore

public FileByteStore(File file)
              throws IOException

Constructs a new FileByteStore which uses the given file as a backing store. Nothing is done to mark this file as temporary.

Parameters:

file - location of the backing file which will be used

Throws:

IOException - if there is some I/O-related problem with opening the file

SecurityException - if the current security context does not allow writing to a temporary file

FileByteStore

public FileByteStore()
              throws IOException

Constructs a new FileByteStore which uses a temporary file as backing store. The temporary file will be written to the default temporary directory, given by the value of the java.io.tmpdir system property.

Throws:

IOException - if there is some I/O-related problem with opening the file

SecurityException - if the current security context does not allow writing to a temporary file

Method Detail

getFile

public File getFile()

Returns the file used by this store.

Returns:

file

getOutputStream

public OutputStream getOutputStream()

Description copied from interface: ByteStore

Returns an output stream which can be used to write to the store. May be called multiple times; always returns the same object. Note that this is not in general buffered - it is the responsibility of the user to take steps like wrapping it in a BufferedOutputStream for efficiency if required.

Specified by:

getOutputStream in interface ByteStore

Returns:

data sink stream

getLength

public long getLength()

Description copied from interface: ByteStore

Returns the number of bytes currently stored in this object.

Specified by:

getLength in interface ByteStore

Returns:

byte count

copy

public void copy(OutputStream out)
          throws IOException

Description copied from interface: ByteStore

Takes all the data written so far into this store's sink stream and copies it to a destination stream. The output stream is not closed.

Specified by:

copy in interface ByteStore

Parameters:

out - data destination stream

Throws:

IOException

toByteBuffers

public ByteBuffer[] toByteBuffers()
                           throws IOException

Description copied from interface: ByteStore

Returns an array of byte buffers containing the bytes written to this store. The stored bytes are all of the bytes from the first buffer in the returned array, followed by all in the second, etc. In many cases the returned array will, and probably should, contain a single buffer, but if the written byte count exceeds Integer.MAX_VALUE, more than one will be required. The limit of each buffer indicates the number of bytes it contains.

Usual usage will be to write all data, then call this method once; this model may affect implementation decisions about efficiency.

Specified by:

toByteBuffers in interface ByteStore

Returns:

byte buffer containing bytes written

Throws:

IOException - if there is an I/O error

copy

public static void copy(File file,
                        OutputStream out)
                 throws IOException

Utility method to copy the contents of a file to an output stream. The stream is not closed.

Parameters:

file - file

out - destination stream

Throws:

IOException

toByteBuffers

public static ByteBuffer[] toByteBuffers(File file)
                                  throws IOException

Returns a read-only ByteBuffer array representing the contents of a file, with default maximum buffer length. If the file can be represented in a single ByteBuffer the result will be a single-element array; otherwise the concatenation of the buffers in the result gives the file content.

Parameters:

file - file

Returns:

mapped byte buffers

Throws:

IOException

close

public void close()

Description copied from interface: ByteStore

Tidies up. Should be called when the data in this object is no longer required. This object may no longer be usable following a call to this method.

Specified by:

close in interface ByteStore