com.twelvemonkeys.io
Class SeekableInputStream

java.lang.Object
  java.io.InputStream
      com.twelvemonkeys.io.SeekableInputStream

All Implemented Interfaces:

Seekable, java.io.Closeable

Direct Known Subclasses:

FileCacheSeekableStream, FileSeekableStream, MemoryCacheSeekableStream

public abstract class SeekableInputStream
extends java.io.InputStream
implements Seekable

Abstract base class for InputStreams implementing the Seekable interface.

Version:

$Id: //depot/branches/personal/haraldk/twelvemonkeys/release-2/twelvemonkeys-core/src/main/java/com/twelvemonkeys/io/SeekableInputStream.java#4 $

Author:

Harald Kuhr

See Also:

SeekableOutputStream

Field Summary

protected java.util.Stack<java.lang.Long>

markedPositions

Constructor Summary

SeekableInputStream()

Method Summary

protected void	checkOpen()
void	close() Closes the stream.
protected abstract void	closeImpl()
protected void	finalize() Finalizes this object prior to garbage collection.
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.
protected abstract void	flushBeforeImpl(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.
void	mark() Marks a position in the stream to be returned to by a subsequent call to reset.
void	mark(int pLimit)
boolean	markSupported() Returns true, as marking is always supported.
int	read(byte[] pBytes)
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.
protected abstract void	seekImpl(long pPosition)
long	skip(long pLength) Implemented using seek(currentPos + pLength).

Methods inherited from class java.io.InputStream

available, read, read

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.twelvemonkeys.io.Seekable

isCached, isCachedFile, isCachedMemory

Field Detail

markedPositions

protected java.util.Stack<java.lang.Long> markedPositions

Constructor Detail

SeekableInputStream

public SeekableInputStream()

Method Detail

read

public final int read(byte[] pBytes)
               throws java.io.IOException

Overrides:

read in class java.io.InputStream

Throws:

java.io.IOException

skip

public final long skip(long pLength)
                throws java.io.IOException

Implemented using seek(currentPos + pLength).

Overrides:

skip in class java.io.InputStream

Parameters:

pLength - the number of bytes to skip

Returns:

the actual number of bytes skipped (may be equal to or less than pLength)

Throws:

java.io.IOException - if an I/O exception occurs during skip

mark

public final void mark(int pLimit)

Overrides:

mark in class java.io.InputStream

markSupported

public final boolean markSupported()

Returns true, as marking is always supported.

Overrides:

markSupported in class java.io.InputStream

Returns:

true.

seek

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

Description copied from interface: Seekable

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 Seekable.getFlushedPosition()).

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

Specified by:

seek in interface Seekable

Parameters:

pPosition - a long containing the desired file pointer position.

Throws:

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

seekImpl

protected abstract void seekImpl(long pPosition)
                          throws java.io.IOException

Throws:

java.io.IOException

mark

public final void mark()

Description copied from interface: Seekable

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.

Specified by:

mark in interface Seekable

reset

public final void reset()
                 throws java.io.IOException

Description copied from interface: Seekable

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.

Specified by:

reset in interface Seekable

Overrides:

reset in class java.io.InputStream

Throws:

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

See Also:

InputStream.reset()

flushBefore

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

Description copied from interface: Seekable

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.

Specified by:

flushBefore in interface Seekable

Parameters:

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

Throws:

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

flushBeforeImpl

protected abstract void flushBeforeImpl(long pPosition)
                                 throws java.io.IOException

Discards the initial portion of the stream prior to the indicated postion.

Parameters:

pPosition - the position to flush to

Throws:

java.io.IOException - if an I/O exception occurs during the flush operation

See Also:

flushBefore(long)

flush

public final void flush()
                 throws java.io.IOException

Description copied from interface: Seekable

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

Specified by:

flush in interface Seekable

Throws:

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

getFlushedPosition

public final long getFlushedPosition()
                              throws java.io.IOException

Description copied from interface: Seekable

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.

Specified by:

getFlushedPosition in interface Seekable

Returns:

the earliest legal position for seeking, as a long.

Throws:

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

getStreamPosition

public final long getStreamPosition()
                             throws java.io.IOException

Description copied from interface: Seekable

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

Specified by:

getStreamPosition in interface Seekable

Returns:

a long containing the position of the stream.

Throws:

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

checkOpen

protected final void checkOpen()
                        throws java.io.IOException

Throws:

java.io.IOException

close

public final void close()
                 throws java.io.IOException

Description copied from interface: Seekable

Closes the stream.

Specified by:

close in interface Seekable

Specified by:

close in interface java.io.Closeable

Overrides:

close in class java.io.InputStream

Throws:

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

closeImpl

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

Throws:

java.io.IOException

finalize

protected void finalize()
                 throws java.lang.Throwable

Finalizes this object prior to garbage collection. The close method is called to close any open input source. This method should not be called from application code.

Overrides:

finalize in class java.lang.Object

Throws:

java.lang.Throwable - if an error occurs during superclass finalization.