Package org.apache.poi.poifs.storage

Class BATBlock

  • All Implemented Interfaces:
    BlockWritable
    public final class BATBlock
extends Object
implements BlockWritable
    A block of block allocation table entries. BATBlocks are created only through a static factory method: createBATBlocks.

    • Method Detail

      • createBATBlock

        public static BATBlock createBATBlock​(POIFSBigBlockSize bigBlockSize,
                                      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,
                                                            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,
                                                             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​(OutputStream stream)
                 throws 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:
        IOException - on problems writing to the specified stream

      • writeData

        public void writeData​(ByteBuffer block)