org.apache.hadoop.io.compress.zlib
Class ZlibDecompressor

java.lang.Object
  org.apache.hadoop.io.compress.zlib.ZlibDecompressor

All Implemented Interfaces:

Decompressor

public class ZlibDecompressor
extends Object
implements Decompressor

A Decompressor based on the popular zlib compression algorithm. http://www.zlib.net/

Nested Class Summary

static class

ZlibDecompressor.CompressionHeader The headers to detect from compressed data.

Constructor Summary

ZlibDecompressor()

ZlibDecompressor(ZlibDecompressor.CompressionHeader header, int directBufferSize)
Creates a new decompressor.

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.
protected void	finalize()
boolean	finished() Returns true if the end of the decompressed data output stream has been reached.
long	getBytesRead() Returns the total number of compressed bytes input so far.
long	getBytesWritten() Returns the total number of uncompressed bytes output so far.
int	getRemaining() Returns the number of bytes remaining in the input buffers; normally called when finished() is true to determine amount of post-gzip-stream data.
boolean	needsDictionary() Returns true if a preset dictionary is needed for decompression.
boolean	needsInput() Returns true if the input data buffer is empty and Decompressor.setInput(byte[], int, int) should be called to provide more input.
void	reset() Resets everything including the input buffers (user and direct).
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.

Methods inherited from class java.lang.Object

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

Constructor Detail

ZlibDecompressor

public ZlibDecompressor(ZlibDecompressor.CompressionHeader header,
                        int directBufferSize)

Creates a new decompressor.

ZlibDecompressor

public ZlibDecompressor()

Method Detail

setInput

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

Description copied from interface: Decompressor

Sets input data for decompression. This should be called if and only if Decompressor.needsInput() returns true indicating that more input data is required. (Both native and non-native versions of various Decompressors require that the data passed in via b[] remain unmodified until the caller is explicitly notified--via Decompressor.needsInput()--that the buffer may be safely modified. With this requirement, an extra buffer-copy can be avoided.)

Specified by:

setInput in interface Decompressor

Parameters:

b - Input data

off - Start offset

len - Length

setDictionary

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

Description copied from interface: Decompressor

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

Specified by:

setDictionary in interface Decompressor

Parameters:

b - Dictionary data bytes

off - Start offset

len - Length

needsInput

public boolean needsInput()

Description copied from interface: Decompressor

Returns true if the input data buffer is empty and Decompressor.setInput(byte[], int, int) should be called to provide more input.

Specified by:

needsInput in interface Decompressor

Returns:

true if the input data buffer is empty and Decompressor.setInput(byte[], int, int) should be called in order to provide more input.

needsDictionary

public boolean needsDictionary()

Description copied from interface: Decompressor

Returns true if a preset dictionary is needed for decompression.

Specified by:

needsDictionary in interface Decompressor

Returns:

true if a preset dictionary is needed for decompression

finished

public boolean finished()

Description copied from interface: Decompressor

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

Specified by:

finished in interface Decompressor

Returns:

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

decompress

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

Description copied from interface: Decompressor

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

Specified by:

decompress in interface Decompressor

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

getBytesWritten

public long getBytesWritten()

Returns the total number of uncompressed bytes output so far.

Returns:

the total (non-negative) number of uncompressed bytes output so far

getBytesRead

public long getBytesRead()

Returns the total number of compressed bytes input so far.

Returns:

the total (non-negative) number of compressed bytes input so far

getRemaining

public int getRemaining()

Returns the number of bytes remaining in the input buffers; normally called when finished() is true to determine amount of post-gzip-stream data.

Specified by:

getRemaining in interface Decompressor

Returns:

the total (non-negative) number of unprocessed bytes in input

reset

public void reset()

Resets everything including the input buffers (user and direct).

Specified by:

reset in interface Decompressor

end

public void end()

Description copied from interface: Decompressor

Closes the decompressor and discards any unprocessed input.

Specified by:

end in interface Decompressor

finalize

protected void finalize()

Overrides:

finalize in class Object