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Class java.util.zip.Deflater

Object
   |
   +----java.util.zip.Deflater

public class Deflater

extends Object

Version:

1.19, 08/20/98

Author:

David Connelly

See Also:

Inflater

BEST_COMPRESSION

Compression level for best compression.

BEST_SPEED

Compression level for fastest compression.

DEFAULT_COMPRESSION

Default compression level.

DEFAULT_STRATEGY

Default compression strategy.

DEFLATED

Compression method for the deflate algorithm (the only one currently supported).

FILTERED

Compression strategy best used for data consisting mostly of small values with a somewhat random distribution.

HUFFMAN_ONLY

Compression strategy for Huffman coding only.

NO_COMPRESSION

Compression level for no compression.

java.util.zip.Deflater(int, boolean)

Creates a new compressor using the specified compression level.

java.util.zip.Deflater(int)

Creates a new compressor using the specified compression level.

java.util.zip.Deflater()

Creates a new compressor with the default compression level.

deflate(byte[], int, int)

Fills specified buffer with compressed data.

deflate(byte[])

Fills specified buffer with compressed data.

end()

Discards unprocessed input and frees internal data.

finalize()

Frees the compressor when garbage is collected.

finish()

When called, indicates that compression should end with the current contents of the input buffer.

finished()

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

getAdler()

Returns the ADLER-32 value of the uncompressed data.

getTotalIn()

Returns the total number of bytes input so far.

getTotalOut()

Returns the total number of bytes output so far.

needsInput()

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

reset()

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

setDictionary(byte[], int, int)

Sets preset dictionary for compression.

setDictionary(byte[])

Sets preset dictionary for compression.

setInput(byte[], int, int)

Sets input data for compression.

setInput(byte[])

Sets input data for compression.

setLevel(int)

Sets the current compression level to the specified value.

setStrategy(int)

Sets the compression strategy to the specified value.

public static final int BEST_COMPRESSION

Compression level for best compression.

public static final int BEST_SPEED

Compression level for fastest compression.

public static final int DEFAULT_COMPRESSION

Default compression level.

public static final int DEFAULT_STRATEGY

Default compression strategy.

public static final int DEFLATED

Compression method for the deflate algorithm (the only one currently supported).

public static final int FILTERED

Compression strategy best used for data consisting mostly of small values with a somewhat random distribution. Forces more Huffman coding and less string matching.

public static final int HUFFMAN_ONLY

Compression strategy for Huffman coding only.

public static final int NO_COMPRESSION

Compression level for no compression.

public Deflater(int level,
                boolean nowrap)

Creates a new compressor using the specified compression level. If 'nowrap' is true then the ZLIB header and checksum fields will not be used in order to support the compression format used in both GZIP and PKZIP.

Parameters:

level - the compression level (0-9)

nowrap - if true then use GZIP compatible compression

public Deflater(int level)

Creates a new compressor using the specified compression level. Compressed data will be generated in ZLIB format.

Parameters:

level - the compression level (0-9)

public Deflater()

Creates a new compressor with the default compression level. Compressed data will be generated in ZLIB format.

public native synchronized int deflate(byte b,
                                       int off,
                                       int len)

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

Parameters:

b - the buffer for the compressed data

off - the start offset of the data

len - the maximum number of bytes of compressed data

Returns:

the actual number of bytes of compressed data

public int deflate(byte b)

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

Parameters:

b - the buffer for the compressed data

Returns:

the actual number of bytes of compressed data

public native synchronized void end()

Discards unprocessed input and frees internal data.

protected void finalize()

Frees the compressor when garbage is collected.

Overrides:

finalize in class Object

public synchronized void finish()

When called, indicates that compression should end with the current contents of the input buffer.

public synchronized boolean finished()

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

public native synchronized int getAdler()

Returns the ADLER-32 value of the uncompressed data.

public native synchronized int getTotalIn()

Returns the total number of bytes input so far.

public native synchronized int getTotalOut()

Returns the total number of bytes output so far.

public boolean needsInput()

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

public native synchronized void reset()

Resets deflater so that a new set of input data can be processed. Keeps current compression level and strategy settings.

public native synchronized 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. When the data is later uncompressed with Inflater.inflate(), Inflater.getAdler() can be called in order to get the Adler-32 value of the dictionary required for decompression.

Parameters:

b - the dictionary data bytes

off - the start offset of the data

len - the length of the data

See Also:

inflate, getAdler

public void setDictionary(byte b)

Sets preset dictionary for compression. A preset dictionary is used when the history buffer can be predetermined. When the data is later uncompressed with Inflater.inflate(), Inflater.getAdler() can be called in order to get the Adler-32 value of the dictionary required for decompression.

Parameters:

b - the dictionary data bytes

See Also:

inflate, getAdler

public synchronized void setInput(byte b,
                                  int off,
                                  int len)

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

Parameters:

b - the input data bytes

off - the start offset of the data

len - the length of the data

See Also:

needsInput

public void setInput(byte b)

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

Parameters:

b - the input data bytes

See Also:

needsInput

public synchronized void setLevel(int level)

Sets the current compression level to the specified value.

Parameters:

level - the new compression level (0-9)

Throws: IllegalArgumentException

if the compression level is invalid

public synchronized void setStrategy(int strategy)

Sets the compression strategy to the specified value.

Parameters:

strategy - the new compression strategy

Throws: IllegalArgumentException

if the compression strategy is invalid

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