Class Deflater

public static final int BEST_COMPRESSION

The best and slowest compression level. This tries to find very long and distant string repetitions.

Field Value:

9

public static final int BEST_SPEED

The worst but fastest compression level.

Field Value:

1

public static final int DEFAULT_COMPRESSION

The default compression level.

Field Value:

-1

public static final int DEFAULT_STRATEGY

The default strategy.

Field Value:

0

public static final int DEFLATED

The compression method. This is the only method supported so far. There is no need to use this constant at all.

Field Value:

8

public static final int FILTERED

This strategy will only allow longer string repetitions. It is useful for random data with a small character set.

Field Value:

1

public static final int HUFFMAN_ONLY

This strategy will not look for string repetitions at all. It only encodes with Huffman trees (which means, that more common characters get a smaller encoding.

Field Value:

2

public static final int NO_COMPRESSION

This level won't compress at all but output uncompressed blocks.

Field Value:

0

public Deflater()

Creates a new deflater with default compression level.

public Deflater(int lvl)

Creates a new deflater with given compression level.

Parameters:

lvl - the compression level, a value between NO_COMPRESSION and BEST_COMPRESSION, or DEFAULT_COMPRESSION.

Throws:

IllegalArgumentException - if lvl is out of range.

public Deflater(int lvl,
                boolean nowrap)

Creates a new deflater with given compression level.

Parameters:

lvl - the compression level, a value between NO_COMPRESSION and BEST_COMPRESSION.

nowrap - true, iff we should suppress the deflate header at the beginning and the adler checksum at the end of the output. This is useful for the GZIP format.

Throws:

IllegalArgumentException - if lvl is out of range.

public int deflate(byte[] output)

Deflates the current input block to the given array. It returns the number of bytes compressed, or 0 if either needsInput() or finished() returns true or length is zero.

Parameters:

output - the buffer where to write the compressed data.

public int deflate(byte[] output,
                   int offset,
                   int length)

Deflates the current input block to the given array. It returns the number of bytes compressed, or 0 if either needsInput() or finished() returns true or length is zero.

Parameters:

output - the buffer where to write the compressed data.

offset - the offset into the output array.

length - the maximum number of bytes that may be written.

Throws:

IllegalStateException - if end() was called.

IndexOutOfBoundsException - if offset and/or length don't match the array length.

public void end()

Frees all objects allocated by the compressor. There's no reason to call this, since you can just rely on garbage collection. Exists only for compatibility against Sun's JDK, where the compressor allocates native memory. If you call any method (even reset) afterwards the behaviour is undefined.

protected void finalize()

Finalizes this object.

Overrides:

finalize in interface Object

public void finish()

Finishes the deflater with the current input block. It is an error to give more input after this method was called. This method must be called to force all bytes to be flushed.

public boolean finished()

Returns true iff the stream was finished and no more output bytes are available.

public int getAdler()

Gets the current adler checksum of the data that was processed so far.

public long getBytesRead()

Gets the number of input bytes processed so far.

Since:

1.5

public long getBytesWritten()

Gets the number of output bytes so far.

Since:

1.5

public @Deprecated int getTotalIn()

Gets the number of input bytes processed so far.

public @Deprecated int getTotalOut()

Gets the number of output bytes so far.

public boolean needsInput()

Returns true, if the input buffer is empty. You should then call setInput().
NOTE: This method can also return true when the stream was finished.

public void reset()

Resets the deflater. The deflater acts afterwards as if it was just created with the same compression level and strategy as it had before.

public void setDictionary(byte[] dict)

Sets the dictionary which should be used in the deflate process. This call is equivalent to setDictionary(dict, 0, dict.length).

Parameters:

dict - the dictionary.

Throws:

IllegalStateException - if setInput () or deflate () were already called or another dictionary was already set.

public void setDictionary(byte[] dict,
                          int offset,
                          int length)

Sets the dictionary which should be used in the deflate process. The dictionary should be a byte array containing strings that are likely to occur in the data which should be compressed. The dictionary is not stored in the compressed output, only a checksum. To decompress the output you need to supply the same dictionary again.

Parameters:

dict - the dictionary.

offset - an offset into the dictionary.

length - the length of the dictionary.

Throws:

IllegalStateException - if setInput () or deflate () were already called or another dictionary was already set.

public void setInput(byte[] input)

Sets the data which should be compressed next. This should be only called when needsInput indicates that more input is needed. If you call setInput when needsInput() returns false, the previous input that is still pending will be thrown away. The given byte array should not be changed, before needsInput() returns true again. This call is equivalent to setInput(input, 0, input.length).

Parameters:

input - the buffer containing the input data.

Throws:

IllegalStateException - if the buffer was finished() or ended().

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

Sets the data which should be compressed next. This should be only called when needsInput indicates that more input is needed. The given byte array should not be changed, before needsInput() returns true again.

Parameters:

input - the buffer containing the input data.

off - the start of the data.

len - the length of the data.

Throws:

IllegalStateException - if the buffer was finished() or ended() or if previous input is still pending.

public void setLevel(int lvl)

Sets the compression level. There is no guarantee of the exact position of the change, but if you call this when needsInput is true the change of compression level will occur somewhere near before the end of the so far given input.

Parameters:

lvl - the new compression level.

public void setStrategy(int stgy)

Sets the compression strategy. Strategy is one of DEFAULT_STRATEGY, HUFFMAN_ONLY and FILTERED. For the exact position where the strategy is changed, the same as for setLevel() applies.

Parameters:

stgy - the new compression strategy.