org.apache.hadoop.io.compress
Interface Decompressor

All Known Implementing Classes:

BuiltInZlibInflater, LzoDecompressor, ZlibDecompressor

public interface Decompressor

Specification of a stream-based 'de-compressor' which can be plugged into a CompressionInputStream to compress data. This is modelled after Inflater

Method Summary

int	decompress(byte[] b, int off, int len) Fills specified buffer with uncompressed data.
void	end() Closes the decompressor and discards any unprocessed input.
boolean	finished() Returns true if the end of the compressed data output stream has been reached.
boolean	needsDictionary() Returns true if a preset dictionary is needed for decompression.
boolean	needsInput() Returns true if the input data buffer is empty and #setInput() should be called to provide more input.
void	reset() Resets decompressor so that a new set of input data can be processed.
void	setDictionary(byte[] b, int off, int len) Sets preset dictionary for compression.
void	setInput(byte[] b, int off, int len) Sets input data for decompression.

Method Detail

setInput

void setInput(byte[] b,
              int off,
              int len)

Sets input data for decompression. This should be called whenever #needsInput() returns true indicating that more input data is required.

Parameters:

b - Input data

off - Start offset

len - Length

needsInput

boolean needsInput()

Returns true if the input data buffer is empty and #setInput() should be called to provide more input.

Returns:

true if the input data buffer is empty and #setInput() should be called in order to provide more input.

setDictionary

void setDictionary(byte[] b,
                   int off,
                   int len)

Sets preset dictionary for compression. A preset dictionary is used when the history buffer can be predetermined.

Parameters:

b - Dictionary data bytes

off - Start offset

len - Length

needsDictionary

boolean needsDictionary()

Returns true if a preset dictionary is needed for decompression.

Returns:

true if a preset dictionary is needed for decompression

finished

boolean finished()

Returns true if the end of the compressed data output stream has been reached.

Returns:

true if the end of the compressed data output stream has been reached.

decompress

int decompress(byte[] b,
               int off,
               int len)
               throws IOException

Fills specified buffer with uncompressed data. Returns actual number of bytes of uncompressed data. A return value of 0 indicates that #needsInput() should be called in order to determine if more input data is required.

Parameters:

b - Buffer for the compressed data

off - Start offset of the data

len - Size of the buffer

Returns:

The actual number of bytes of compressed data.

Throws:

IOException

reset

void reset()

Resets decompressor so that a new set of input data can be processed.

end

void end()

Closes the decompressor and discards any unprocessed input.