com.twelvemonkeys.io

Interface Seekable

All Known Implementing Classes:

FileCacheSeekableStream, FileSeekableStream, MemoryCacheSeekableStream, RandomAccessStream, SeekableInputStream, SeekableOutputStream

public interface Seekable

Interface for seekable streams.

Version:

$Id: //depot/branches/personal/haraldk/twelvemonkeys/release-2/twelvemonkeys-core/src/main/java/com/twelvemonkeys/io/Seekable.java#1 $

Author:

Harald Kuhr

See Also:

SeekableInputStream, SeekableOutputStream

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Closes the stream.
void	flush() Discards the initial position of the stream prior to the current stream position.
void	flushBefore(long pPosition) Discards the initial portion of the stream prior to the indicated postion.
long	getFlushedPosition() Returns the earliest position in the stream to which seeking may be performed.
long	getStreamPosition() Returns the current byte position of the stream.
boolean	isCached() Returns true if this Seekable stream caches data itself in order to allow seeking backwards.
boolean	isCachedFile() Returns true if this Seekable stream caches data itself in order to allow seeking backwards, and the cache is kept in a temporary file.
boolean	isCachedMemory() Returns true if this Seekable stream caches data itself in order to allow seeking backwards, and the cache is kept in main memory.
void	mark() Marks a position in the stream to be returned to by a subsequent call to reset.
void	reset() Returns the file pointer to its previous position, at the time of the most recent unmatched call to mark.
void	seek(long pPosition) Sets the current stream position to the desired location.

Method Detail

getStreamPosition

long getStreamPosition()
                       throws java.io.IOException

Returns the current byte position of the stream. The next read will take place starting at this offset.

Returns:

a long containing the position of the stream.

Throws:

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

seek

void seek(long pPosition)
          throws java.io.IOException

Sets the current stream position to the desired location. The next read will occur at this location.

An IndexOutOfBoundsException will be thrown if pPosition is smaller than the flushed position (as returned by getFlushedPosition()).

It is legal to seek past the end of the file; an EOFException will be thrown only if a read is performed.

Parameters:

pPosition - a long containing the desired file pointer position.

Throws:

java.lang.IndexOutOfBoundsException - if pPosition is smaller than the flushed position.

java.io.IOException - if any other I/O error occurs.

mark

void mark()

Marks a position in the stream to be returned to by a subsequent call to reset. Unlike a standard InputStream, all Seekable streams upport marking. Additionally, calls to mark and reset may be nested arbitrarily.

Unlike the mark methods declared by the Reader or InputStream interfaces, no readLimit parameter is used. An arbitrary amount of data may be read following the call to mark.

reset

void reset()
           throws java.io.IOException

Returns the file pointer to its previous position, at the time of the most recent unmatched call to mark.

Calls to reset without a corresponding call to mark will either:

• throw an IOException
• or, reset to the beginning of the stream.

An IOException will be thrown if the previous marked position lies in the discarded portion of the stream.

Throws:

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

See Also:

InputStream.reset()

flushBefore

void flushBefore(long pPosition)
                 throws java.io.IOException

Discards the initial portion of the stream prior to the indicated postion. Attempting to seek to an offset within the flushed portion of the stream will result in an IndexOutOfBoundsException.

Calling flushBefore may allow classes implementing this interface to free up resources such as memory or disk space that are being used to store data from the stream.

Parameters:

pPosition - a long containing the length of the file prefix that may be flushed.

Throws:

java.lang.IndexOutOfBoundsException - if pPosition lies in the flushed portion of the stream or past the current stream position.

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

flush

void flush()
           throws java.io.IOException

Discards the initial position of the stream prior to the current stream position. Equivalent to flushBefore(getStreamPosition()).

Throws:

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

getFlushedPosition

long getFlushedPosition()
                        throws java.io.IOException

Returns the earliest position in the stream to which seeking may be performed. The returned value will be the maximum of all values passed into previous calls to flushBefore.

Returns:

the earliest legal position for seeking, as a long.

Throws:

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

isCached

boolean isCached()

Returns true if this Seekable stream caches data itself in order to allow seeking backwards. Applications may consult this in order to decide how frequently, or whether, to flush in order to conserve cache resources.

Returns:

true if this Seekable caches data.

See Also:

isCachedMemory(), isCachedFile()

isCachedMemory

boolean isCachedMemory()

Returns true if this Seekable stream caches data itself in order to allow seeking backwards, and the cache is kept in main memory. Applications may consult this in order to decide how frequently, or whether, to flush in order to conserve cache resources.

Returns:

true if this Seekable caches data in main memory.

See Also:

isCached(), isCachedFile()

isCachedFile

boolean isCachedFile()

Returns true if this Seekable stream caches data itself in order to allow seeking backwards, and the cache is kept in a temporary file. Applications may consult this in order to decide how frequently, or whether, to flush in order to conserve cache resources.

Returns:

true if this Seekable caches data in a temporary file.

See Also:

isCached(), isCachedMemory()

close

void close()
           throws java.io.IOException

Closes the stream.

Throws:

java.io.IOException - if the stream can't be closed.