java.util.zip

Class Inflater

public class Inflater extends Object

Inflater is used to decompress data that has been compressed according to the "deflate" standard described in rfc1950. The usage is as following. First you have to set some input with setInput(), then inflate() it. If inflate doesn't inflate any bytes there may be three reasons:

needsInput() returns true because the input buffer is empty. You have to provide more input with setInput(). NOTE: needsInput() also returns true when, the stream is finished.
needsDictionary() returns true, you have to provide a preset dictionary with setDictionary().
finished() returns true, the inflater has finished.

Once the first output byte is produced, a dictionary will not be needed at a later stage.

Since: JDK 1.1

UNKNOWN: May 17, 1999

Constructor Summary
	Inflater() Creates a new inflater.
	Inflater(boolean nowrap) Creates a new inflater.

Method Summary
void	end() Frees all objects allocated by the inflater.
protected void	finalize() Finalizes this object.
boolean	finished() Returns true, if the inflater has finished.
int	getAdler() Gets the adler checksum.
long	getBytesRead() Gets the total number of processed compressed input bytes.
long	getBytesWritten() Gets the total number of output bytes returned by inflate().
int	getRemaining() Gets the number of unprocessed input.
int	inflate(byte[] buf) Inflates the compressed stream to the output buffer.
int	inflate(byte[] buf, int off, int len) Inflates the compressed stream to the output buffer.
boolean	needsDictionary() Returns true, if a preset dictionary is needed to inflate the input.
boolean	needsInput() Returns true, if the input buffer is empty.
void	reset() Resets the inflater so that a new stream can be decompressed.
void	setDictionary(byte[] buffer) Sets the preset dictionary.
void	setDictionary(byte[] buffer, int off, int len) Sets the preset dictionary.
void	setInput(byte[] buf) Sets the input.
void	setInput(byte[] buf, int off, int len) Sets the input.

Constructor Detail

Inflater

public Inflater()

Creates a new inflater.

Inflater

public Inflater(boolean nowrap)

Creates a new inflater.

Parameters: nowrap true if no header and checksum field appears in the stream. This is used for GZIPed input. For compatibility with Sun JDK you should provide one byte of input more than needed in this case.

Method Detail

end

public void end()

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

finalize

protected void finalize()

Finalizes this object.

finished

public boolean finished()

Returns true, if the inflater has finished. This means, that no input is needed and no output can be produced.

getAdler

public int getAdler()

Gets the adler checksum. This is either the checksum of all uncompressed bytes returned by inflate(), or if needsDictionary() returns true (and thus no output was yet produced) this is the adler checksum of the expected dictionary.

UNKNOWN: the adler checksum.

getBytesRead

public long getBytesRead()

Gets the total number of processed compressed input bytes.

Returns: the total number of bytes of processed input bytes.

Since: 1.5

getBytesWritten

public long getBytesWritten()

Gets the total number of output bytes returned by inflate().

Returns: the total number of output bytes.

Since: 1.5

getRemaining

public int getRemaining()

Gets the number of unprocessed input. Useful, if the end of the stream is reached and you want to further process the bytes after the deflate stream.

Returns: the number of bytes of the input which were not processed.

inflate

public int inflate(byte[] buf)

Inflates the compressed stream to the output buffer. If this returns 0, you should check, whether needsDictionary(), needsInput() or finished() returns true, to determine why no further output is produced.

Parameters: buf the output buffer.

Returns: the number of bytes written to the buffer, 0 if no further output can be produced.

Throws: DataFormatException if deflated stream is invalid. IllegalArgumentException if buf has length 0.

inflate

public int inflate(byte[] buf, int off, int len)

Parameters: buf the output buffer. off the offset into buffer where the output should start. len the maximum length of the output.

Returns: the number of bytes written to the buffer, 0 if no further output can be produced.

Throws: DataFormatException if deflated stream is invalid. IndexOutOfBoundsException if the off and/or len are wrong.

needsDictionary

public boolean needsDictionary()

Returns true, if a preset dictionary is needed to inflate the input.

needsInput

public boolean needsInput()

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

reset

public void reset()

Resets the inflater so that a new stream can be decompressed. All pending input and output will be discarded.

setDictionary

public void setDictionary(byte[] buffer)

Sets the preset dictionary. This should only be called, if needsDictionary() returns true and it should set the same dictionary, that was used for deflating. The getAdler() function returns the checksum of the dictionary needed.

Parameters: buffer the dictionary.

Throws: IllegalStateException if no dictionary is needed. IllegalArgumentException if the dictionary checksum is wrong.

setDictionary

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

Parameters: buffer the dictionary. off the offset into buffer where the dictionary starts. len the length of the dictionary.

Throws: IllegalStateException if no dictionary is needed. IllegalArgumentException if the dictionary checksum is wrong. IndexOutOfBoundsException if the off and/or len are wrong.

setInput

public void setInput(byte[] buf)

Sets the input. This should only be called, if needsInput() returns true.

Parameters: buf the input.

Throws: IllegalStateException if no input is needed.

setInput

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

Sets the input. This should only be called, if needsInput() returns true.

Parameters: buf the input. off the offset into buffer where the input starts. len the length of the input.

Throws: IllegalStateException if no input is needed. IndexOutOfBoundsException if the off and/or len are wrong.