Package org.docx4j.org.apache.poi.poifs.storage

Class BlockAllocationTableWriter

java.lang.Object
org.docx4j.org.apache.poi.poifs.storage.BlockAllocationTableWriter
All Implemented Interfaces:
BATManaged, BlockWritable
public final class BlockAllocationTableWriter
extends java.lang.Object
implements BlockWritable, BATManaged
This class manages and creates the Block Allocation Table, which is basically a set of linked lists of block indices.

Each block of the filesystem has an index. The first block, the header, is skipped; the first block after the header is index 0, the next is index 1, and so on.

A block's index is also its index into the Block Allocation Table. The entry that it finds in the Block Allocation Table is the index of the next block in the linked list of blocks making up a file, or it is set to -2: end of list.

Author:
Marc Johnson (mjohnson at apache dot org)

  • Constructor Summary

    Constructors 
    Constructor Description
    BlockAllocationTableWriter​(POIFSBigBlockSize bigBlockSize)
    create a BlockAllocationTableWriter

  • Method Summary

    Modifier and Type Method Description
    int allocateSpace​(int blockCount)
    Allocate space for a block of indices
    int countBlocks()
    Return the number of BigBlock's this instance uses
    int createBlocks()
    Create the BATBlocks we need
    int getStartBlock()
    get the starting block
    void setStartBlock​(int start_block)
    Set the start block for this instance
    static void writeBlock​(BATBlock bat, java.nio.ByteBuffer block)
    Write the BAT into its associated block
    void writeBlocks​(java.io.OutputStream stream)
    Write the storage to an OutputStream

    Methods inherited from class java.lang.Object

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

  • Constructor Details

  • Method Details

    • createBlocks

      public int createBlocks()
      Create the BATBlocks we need
      Returns:
      start block index of BAT blocks

    • allocateSpace

      public int allocateSpace​(int blockCount)
      Allocate space for a block of indices
      Parameters:
      blockCount - the number of blocks to allocate space for
      Returns:
      the starting index of the blocks

    • getStartBlock

      public int getStartBlock()
      get the starting block
      Returns:
      the starting block index

    • writeBlocks

      public void writeBlocks​(java.io.OutputStream stream) throws java.io.IOException
      Write the storage 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

    • writeBlock

      public static void writeBlock​(BATBlock bat, java.nio.ByteBuffer block) throws java.io.IOException
      Write the BAT into its associated block
      Throws:
      java.io.IOException

    • countBlocks

      public int countBlocks()
      Return the number of BigBlock's this instance uses
      Specified by:
      countBlocks in interface BATManaged
      Returns:
      count of BigBlock instances

    • setStartBlock

      public void setStartBlock​(int start_block)
      Set the start block for this instance
      Specified by:
      setStartBlock in interface BATManaged
      Parameters:
      start_block - index into the array of BigBlock instances making up the the filesystem