org.apache.poi.poifs.storage

Class BATBlock

java.lang.Object

org.apache.poi.poifs.storage.BATBlock

All Implemented Interfaces:

BlockWritable

public final class BATBlock
extends java.lang.Object
implements BlockWritable

A block of block allocation table entries. BATBlocks are created only through a static factory method: createBATBlocks.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BATBlock.BATBlockAndIndex

Method Summary

Modifier and Type	Method and Description
static long	calculateMaximumSize(HeaderBlock header)
static long	calculateMaximumSize(POIFSBigBlockSize bigBlockSize, int numBATs) Calculates the maximum size of a file which is addressable given the number of FAT (BAT) sectors specified.
static BATBlock	createBATBlock(POIFSBigBlockSize bigBlockSize, java.nio.ByteBuffer data) Create a single BATBlock from the byte buffer, which must hold at least one big block of data to be read.
static BATBlock	createEmptyBATBlock(POIFSBigBlockSize bigBlockSize, boolean isXBAT) Creates a single BATBlock, with all the values set to empty.
static BATBlock.BATBlockAndIndex	getBATBlockAndIndex(int offset, HeaderBlock header, java.util.List<BATBlock> bats) Returns the BATBlock that handles the specified offset, and the relative index within it.
int	getOccupiedSize() How much of this block is occupied?.
int	getOurBlockIndex() Retrieve where in the file we live
static BATBlock.BATBlockAndIndex	getSBATBlockAndIndex(int offset, HeaderBlock header, java.util.List<BATBlock> sbats) Returns the BATBlock that handles the specified offset, and the relative index within it, for the mini stream.
int	getUsedSectors(boolean isAnXBAT) How many sectors in this block are taken? Note that calling hasFreeSectors() is much quicker
int	getValueAt(int relativeOffset)
boolean	hasFreeSectors() Does this BATBlock have any free sectors in it, or is it full?
void	setOurBlockIndex(int index) Record where in the file we live
void	setValueAt(int relativeOffset, int value)
void	writeBlocks(java.io.OutputStream stream) Write the block's data to an OutputStream
void	writeData(java.nio.ByteBuffer block)

Methods inherited from class java.lang.Object

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

Method Detail

createBATBlock

public static BATBlock createBATBlock(POIFSBigBlockSize bigBlockSize,
                                      java.nio.ByteBuffer data)

Create a single BATBlock from the byte buffer, which must hold at least one big block of data to be read.

createEmptyBATBlock

public static BATBlock createEmptyBATBlock(POIFSBigBlockSize bigBlockSize,
                                           boolean isXBAT)

Creates a single BATBlock, with all the values set to empty.

calculateMaximumSize

public static long calculateMaximumSize(POIFSBigBlockSize bigBlockSize,
                                        int numBATs)

Calculates the maximum size of a file which is addressable given the number of FAT (BAT) sectors specified. (We don't care if those BAT blocks come from the 109 in the header, or from header + XBATS, it won't affect the calculation) The actual file size will be between [size of fatCount-1 blocks] and [size of fatCount blocks]. For 512 byte block sizes, this means we may over-estimate by up to 65kb. For 4096 byte block sizes, this means we may over-estimate by up to 4mb

calculateMaximumSize

public static long calculateMaximumSize(HeaderBlock header)

getBATBlockAndIndex

public static BATBlock.BATBlockAndIndex getBATBlockAndIndex(int offset,
                                                            HeaderBlock header,
                                                            java.util.List<BATBlock> bats)

Returns the BATBlock that handles the specified offset, and the relative index within it. The List of BATBlocks must be in sequential order

getSBATBlockAndIndex

public static BATBlock.BATBlockAndIndex getSBATBlockAndIndex(int offset,
                                                             HeaderBlock header,
                                                             java.util.List<BATBlock> sbats)

Returns the BATBlock that handles the specified offset, and the relative index within it, for the mini stream. The List of BATBlocks must be in sequential order

hasFreeSectors

public boolean hasFreeSectors()

Does this BATBlock have any free sectors in it, or is it full?

getUsedSectors

public int getUsedSectors(boolean isAnXBAT)

How many sectors in this block are taken? Note that calling hasFreeSectors() is much quicker

getOccupiedSize

public int getOccupiedSize()

How much of this block is occupied?. This counts the number of sectors up and including the last used sector. Note that this is different from getUsedSectors(boolean) which could be smaller as it does not count unused sectors where there are used ones after it (i.e. fragmentation).

Since:

POI 5.0.0

getValueAt

public int getValueAt(int relativeOffset)

setValueAt

public void setValueAt(int relativeOffset,
                       int value)

setOurBlockIndex

public void setOurBlockIndex(int index)

Record where in the file we live

getOurBlockIndex

public int getOurBlockIndex()

Retrieve where in the file we live

writeBlocks

public void writeBlocks(java.io.OutputStream stream)
                 throws java.io.IOException

Write the block's data to an OutputStream

Specified by:

writeBlocks in interface BlockWritable

Parameters:

stream - the OutputStream to which the stored data should be written

Throws:

java.io.IOException - on problems writing to the specified stream

writeData

public void writeData(java.nio.ByteBuffer block)