compoundfile.java

jxtl API Java中Excel的生成与导入解析参考文档

   * @return the defragmented ole stream
   * @exception BiffException
   */
  public byte[] getStream(String streamName) throws BiffException
  {
    PropertyStorage ps = findPropertyStorage(streamName, 
                                             rootEntryPropertyStorage);

    // Property set can't be found from the direct hierarchy, so just
    // search on the name
    if (ps == null)
    {
      ps = getPropertyStorage(streamName);
    }

    if (ps.size >= SMALL_BLOCK_THRESHOLD ||
        streamName.equalsIgnoreCase(ROOT_ENTRY_NAME))
    {
      return getBigBlockStream(ps);
    }
    else
    {
      return getSmallBlockStream(ps);
    }
  }

  /**
   * Gets the defragmented stream from this ole compound file.  Used when
   * copying workbooks with macros
   *
   * @param psIndex the property storage index
   * @return the defragmented ole stream
   * @exception BiffException
   */
  public byte[] getStream(int psIndex) throws BiffException
  {
    PropertyStorage ps = getPropertyStorage(psIndex);

    if (ps.size >= SMALL_BLOCK_THRESHOLD ||
        ps.name.equalsIgnoreCase(ROOT_ENTRY_NAME))
    {
      return getBigBlockStream(ps);
    }
    else
    {
      return getSmallBlockStream(ps);
    }
  }

  /**
   * Recursively searches the property storages in hierarchy order 
   * for the appropriate name.  This is the public version which is
   * invoked from the writable version
   * when copying a sheet with addition property sets.
   */
  public PropertyStorage findPropertyStorage(String name)
  {
    return findPropertyStorage(name, rootEntryPropertyStorage);
  }

  /**
   * Recursively searches the property storages in hierarchy order 
   * for the appropriate name.
   */
  private PropertyStorage findPropertyStorage(String name, 
                                             PropertyStorage base)
  {
    if (base.child == -1)
    {
      return null;
    }

    // Get the child
    PropertyStorage child = getPropertyStorage(base.child);
    if (child.name.equalsIgnoreCase(name))
    {
      return child;
    }

    // Find the previous property storages on the same level
    PropertyStorage prev = child;
    while (prev.previous != -1)
    {
      prev = getPropertyStorage(prev.previous);
      if (prev.name.equalsIgnoreCase(name))
      {
        return prev;
      }      
    }

    // Find the next property storages on the same level
    PropertyStorage next = child;
    while (next.next != -1)
    {
      next = getPropertyStorage(next.next);
      if (next.name.equalsIgnoreCase(name))
      {
        return next;
      }      
    }

    return findPropertyStorage(name, child);
  }

  /**
   * Gets the property set with the specified name
   * @param name the property storage name
   * @return the property storage record
   * @exception BiffException
   * @deprecated remove me
   */
  private PropertyStorage getPropertyStorage(String name)
    throws BiffException
  {
    // Find the workbook property
    Iterator i = propertySets.iterator();
    boolean found = false;
    boolean multiple = false;
    PropertyStorage ps = null;
    while (i.hasNext())
    {
      PropertyStorage ps2 = (PropertyStorage) i.next();
      if (ps2.name.equalsIgnoreCase(name))
      {
        multiple = found == true ? true : false;
        found = true;
        ps = ps2;
      }
    }

    if (multiple)
    {
      logger.warn("found multiple copies of property set " + name);
    }

    if (!found)
    {
      throw new BiffException(BiffException.streamNotFound);
    }

    return ps;
  }

  /**
   * Gets the property set with the specified name
   * @param index the index of the property storage
   * @return the property storage record
   */
  private PropertyStorage getPropertyStorage(int index)
  {
    return (PropertyStorage) propertySets.get(index);
  }

  /**
   * Build up the resultant stream using the big blocks
   *
   * @param ps the property storage
   * @return the big block stream
   */
  private byte[] getBigBlockStream(PropertyStorage ps)
  {
    int numBlocks = ps.size / BIG_BLOCK_SIZE;
    if (ps.size % BIG_BLOCK_SIZE != 0)
    {
      numBlocks++;
    }

    byte[] streamData = new byte[numBlocks * BIG_BLOCK_SIZE];

    int block = ps.startBlock;

    int count = 0;
    int pos = 0;
    while (block != -2 && count < numBlocks)
    {
      pos = (block + 1) * BIG_BLOCK_SIZE;
      System.arraycopy(data, pos, streamData,
                       count * BIG_BLOCK_SIZE, BIG_BLOCK_SIZE);
      count++;
      block = bigBlockChain[block];
    }

    if (block != -2 && count == numBlocks)
    {
      logger.warn("Property storage size inconsistent with block chain.");
    }

    return streamData;
  }

  /**
   * Build up the resultant stream using the small blocks
   * @param ps the property storage
   * @return  the data
   * @exception BiffException
   */
  private byte[] getSmallBlockStream(PropertyStorage ps)
    throws BiffException
  {
    /*
    PropertyStorage rootps = null;
    try
    {
      rootps = getPropertyStorage(ROOT_ENTRY_NAME);
    }
    catch (BiffException e)
    {
      rootps = (PropertyStorage) propertySets.get(0);
    }
    */

    byte[] rootdata = readData(rootEntryPropertyStorage.startBlock);
    byte[] sbdata = new byte[0];

    int block = ps.startBlock;
    int pos = 0;

    while (block != -2)
    {
      // grow the array
      byte[] olddata = sbdata;
      sbdata = new byte[olddata.length + SMALL_BLOCK_SIZE];
      System.arraycopy(olddata, 0, sbdata, 0, olddata.length);

      // Copy in the new data
      pos = block * SMALL_BLOCK_SIZE;
      System.arraycopy(rootdata, pos, sbdata,
                       olddata.length, SMALL_BLOCK_SIZE);
      block = smallBlockChain[block];

      if (block == -1)
      {
        logger.warn("Incorrect terminator for small block stream " + ps.name);
        block = -2; // kludge to force the loop termination
      }
    }

    return sbdata;
  }

  /**
   * Reads the block chain from the specified block and returns the
   * data as a continuous stream of bytes
   *
   * @param bl the block number
   * @return the data
   */
  private byte[] readData(int bl) throws BiffException
  {
    int block = bl;
    int pos = 0;
    byte[] entry = new byte[0];

    while (block != -2)
    {
      // Grow the array
      byte[] oldEntry = entry;
      entry = new byte[oldEntry.length + BIG_BLOCK_SIZE];
      System.arraycopy(oldEntry, 0, entry, 0, oldEntry.length);
      pos = (block + 1) * BIG_BLOCK_SIZE;
      System.arraycopy(data, pos, entry,
                       oldEntry.length, BIG_BLOCK_SIZE);
      if (bigBlockChain[block] == block)
      {
        throw new BiffException(BiffException.corruptFileFormat);
      }
      block = bigBlockChain[block];
    }
    return entry;
  }

  /**
   * Gets the number of property sets
   * @return the number of property sets
   */
  public int getNumberOfPropertySets()
  {
    return propertySets.size();
  }

  /**
   * Gets the property set.  Invoked when copying worksheets with macros.  
   * Simply calls the private counterpart
   *
   * @param ps the property set name
   * @return the property set with the given name
   */
  public PropertyStorage getPropertySet(int index)
  {
    return getPropertyStorage(index);
  }
}