Package loci.poi.poifs.storage
Class BlockAllocationTableWriter
java.lang.Object
loci.poi.poifs.storage.BlockAllocationTableWriter
- All Implemented Interfaces:
BATManaged,BlockWritable
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)
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionintallocateSpace(int blockCount) Allocate space for a block of indicesintReturn the number of BigBlock's this instance usesintcreateBlocks(int size) Create the BATBlocks we needintget the starting blockvoidsetStartBlock(int start_block) Set the start block for this instancevoidwriteBlocks(OutputStream stream) Write the storage to an OutputStream
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Constructor Details
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BlockAllocationTableWriter
public BlockAllocationTableWriter()create a BlockAllocationTableWriter
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Method Details
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createBlocks
public int createBlocks(int size) Create the BATBlocks we need- Returns:
- start block index of BAT blocks
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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
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getStartBlock
public int getStartBlock()get the starting block- Returns:
- the starting block index
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writeBlocks
Write the storage to an OutputStream- Specified by:
writeBlocksin interfaceBlockWritable- Parameters:
stream- the OutputStream to which the stored data should be written- Throws:
IOException- on problems writing to the specified stream
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countBlocks
public int countBlocks()Return the number of BigBlock's this instance uses- Specified by:
countBlocksin interfaceBATManaged- Returns:
- count of BigBlock instances
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setStartBlock
public void setStartBlock(int start_block) Set the start block for this instance- Specified by:
setStartBlockin interfaceBATManaged- Parameters:
start_block-
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