org.apache.poi.poifs.storage.SmallDocumentBlock Maven / Gradle / Ivy
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this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
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http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.poi.poifs.storage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.apache.poi.poifs.common.POIFSBigBlockSize;
/**
* Storage for documents that are too small to use regular
* DocumentBlocks for their data
*
* @author Marc Johnson (mjohnson at apache dot org)
*/
public final class SmallDocumentBlock implements BlockWritable, ListManagedBlock {
private static final int BLOCK_SHIFT = 6;
private byte[] _data;
private static final byte _default_fill = ( byte ) 0xff;
private static final int _block_size = 1 << BLOCK_SHIFT;
private static final int BLOCK_MASK = _block_size-1;
private final int _blocks_per_big_block;
private final POIFSBigBlockSize _bigBlockSize;
private SmallDocumentBlock(final POIFSBigBlockSize bigBlockSize, final byte [] data, final int index)
{
this(bigBlockSize);
System.arraycopy(data, index * _block_size, _data, 0, _block_size);
}
private SmallDocumentBlock(final POIFSBigBlockSize bigBlockSize)
{
_bigBlockSize = bigBlockSize;
_blocks_per_big_block = getBlocksPerBigBlock(bigBlockSize);
_data = new byte[ _block_size ];
}
private static int getBlocksPerBigBlock(final POIFSBigBlockSize bigBlockSize)
{
return bigBlockSize.getBigBlockSize() / _block_size;
}
/**
* convert a single long array into an array of SmallDocumentBlock
* instances
*
* @param array the byte array to be converted
* @param size the intended size of the array (which may be smaller)
*
* @return an array of SmallDocumentBlock instances, filled from
* the array
*/
public static SmallDocumentBlock [] convert(POIFSBigBlockSize bigBlockSize,
byte [] array,
int size)
{
SmallDocumentBlock[] rval =
new SmallDocumentBlock[ (size + _block_size - 1) / _block_size ];
int offset = 0;
for (int k = 0; k < rval.length; k++)
{
rval[ k ] = new SmallDocumentBlock(bigBlockSize);
if (offset < array.length)
{
int length = Math.min(_block_size, array.length - offset);
System.arraycopy(array, offset, rval[ k ]._data, 0, length);
if (length != _block_size)
{
Arrays.fill(rval[ k ]._data, length, _block_size,
_default_fill);
}
}
else
{
Arrays.fill(rval[ k ]._data, _default_fill);
}
offset += _block_size;
}
return rval;
}
/**
* fill out a List of SmallDocumentBlocks so that it fully occupies
* a set of big blocks
*
* @param blocks the List to be filled out
*
* @return number of big blocks the list encompasses
*/
public static int fill(POIFSBigBlockSize bigBlockSize, List blocks)
{
int _blocks_per_big_block = getBlocksPerBigBlock(bigBlockSize);
int count = blocks.size();
int big_block_count = (count + _blocks_per_big_block - 1)
/ _blocks_per_big_block;
int full_count = big_block_count * _blocks_per_big_block;
for (; count < full_count; count++)
{
blocks.add(makeEmptySmallDocumentBlock(bigBlockSize));
}
return big_block_count;
}
/**
* Factory for creating SmallDocumentBlocks from DocumentBlocks
*
* @param store the original DocumentBlocks
* @param size the total document size
*
* @return an array of new SmallDocumentBlocks instances
*
* @exception IOException on errors reading from the DocumentBlocks
* @exception ArrayIndexOutOfBoundsException if, somehow, the store
* contains less data than size indicates
*/
public static SmallDocumentBlock [] convert(POIFSBigBlockSize bigBlockSize,
BlockWritable [] store,
int size)
throws IOException, ArrayIndexOutOfBoundsException
{
ByteArrayOutputStream stream = new ByteArrayOutputStream();
for (int j = 0; j < store.length; j++)
{
store[ j ].writeBlocks(stream);
}
byte[] data = stream.toByteArray();
SmallDocumentBlock[] rval =
new SmallDocumentBlock[ convertToBlockCount(size) ];
for (int index = 0; index < rval.length; index++)
{
rval[ index ] = new SmallDocumentBlock(bigBlockSize, data, index);
}
return rval;
}
/**
* create a list of SmallDocumentBlock's from raw data
*
* @param blocks the raw data containing the SmallDocumentBlock
* data
*
* @return a List of SmallDocumentBlock's extracted from the input
*/
public static List extract(POIFSBigBlockSize bigBlockSize, ListManagedBlock [] blocks)
throws IOException
{
int _blocks_per_big_block = getBlocksPerBigBlock(bigBlockSize);
List sdbs = new ArrayList();
for (int j = 0; j < blocks.length; j++)
{
byte[] data = blocks[ j ].getData();
for (int k = 0; k < _blocks_per_big_block; k++)
{
sdbs.add(new SmallDocumentBlock(bigBlockSize, data, k));
}
}
return sdbs;
}
public static DataInputBlock getDataInputBlock(SmallDocumentBlock[] blocks, int offset) {
int firstBlockIndex = offset >> BLOCK_SHIFT;
int firstBlockOffset= offset & BLOCK_MASK;
return new DataInputBlock(blocks[firstBlockIndex]._data, firstBlockOffset);
}
/**
* Calculate the storage size of a set of SmallDocumentBlocks
*
* @param size number of SmallDocumentBlocks
*
* @return total size
*/
public static int calcSize(int size)
{
return size * _block_size;
}
private static SmallDocumentBlock makeEmptySmallDocumentBlock(POIFSBigBlockSize bigBlockSize)
{
SmallDocumentBlock block = new SmallDocumentBlock(bigBlockSize);
Arrays.fill(block._data, _default_fill);
return block;
}
private static int convertToBlockCount(int size)
{
return (size + _block_size - 1) / _block_size;
}
/**
* Write the storage to an OutputStream
*
* @param stream the OutputStream to which the stored data should
* be written
*
* @exception IOException on problems writing to the specified
* stream
*/
public void writeBlocks(OutputStream stream)
throws IOException
{
stream.write(_data);
}
/**
* Get the data from the block
*
* @return the block's data as a byte array
*
* @exception IOException if there is no data
*/
public byte [] getData() {
return _data;
}
public POIFSBigBlockSize getBigBlockSize() {
return _bigBlockSize;
}
}
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