- java.lang.Object
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- java.util.zip.Inflater
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public class Inflater extends Object
This class provides support for general purpose decompression using the popular ZLIB compression library. The ZLIB compression library was initially developed as part of the PNG graphics standard and is not protected by patents. It is fully described in the specifications at the java.util.zip package description.This class inflates sequences of ZLIB compressed bytes. The input byte sequence is provided in either byte array or byte buffer, via one of the
setInput()methods. The output byte sequence is written to the output byte array or byte buffer passed to thedeflate()methods.The following code fragment demonstrates a trivial compression and decompression of a string using
DeflaterandInflater.try { // Encode a String into bytes String inputString = "blahblahblah€€"; byte[] input = inputString.getBytes("UTF-8"); // Compress the bytes byte[] output = new byte[100]; Deflater compresser = new Deflater(); compresser.setInput(input); compresser.finish(); int compressedDataLength = compresser.deflate(output); // Decompress the bytes Inflater decompresser = new Inflater(); decompresser.setInput(output, 0, compressedDataLength); byte[] result = new byte[100]; int resultLength = decompresser.inflate(result); decompresser.end(); // Decode the bytes into a String String outputString = new String(result, 0, resultLength, "UTF-8"); } catch (java.io.UnsupportedEncodingException ex) { // handle } catch (java.util.zip.DataFormatException ex) { // handle }- API Note:
- To release resources used by this
Inflater, theend()method should be called explicitly. Subclasses are responsible for the cleanup of resources acquired by the subclass. Subclasses that overridefinalize()in order to perform cleanup should be modified to use alternative cleanup mechanisms such asCleanerand remove the overridingfinalizemethod. - Implementation Requirements:
- If this
Inflaterhas been subclassed and theendmethod has been overridden, theendmethod will be called by the finalization when the inflater is unreachable. But the subclasses should not depend on this specific implementation; the finalization is not reliable and thefinalizemethod is deprecated to be removed. - Since:
- 1.1
- See Also:
Deflater
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Method Summary
All Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method Description voidend()Closes the decompressor and discards any unprocessed input.protected voidfinalize()Deprecated, for removal: This API element is subject to removal in a future version.Thefinalizemethod has been deprecated and will be removed.booleanfinished()Returns true if the end of the compressed data stream has been reached.intgetAdler()Returns the ADLER-32 value of the uncompressed data.longgetBytesRead()Returns the total number of compressed bytes input so far.longgetBytesWritten()Returns the total number of uncompressed bytes output so far.intgetRemaining()Returns the total number of bytes remaining in the input buffer.intgetTotalIn()Returns the total number of compressed bytes input so far.intgetTotalOut()Returns the total number of uncompressed bytes output so far.intinflate(byte[] output)Uncompresses bytes into specified buffer.intinflate(byte[] output, int off, int len)Uncompresses bytes into specified buffer.intinflate(ByteBuffer output)Uncompresses bytes into specified buffer.booleanneedsDictionary()Returns true if a preset dictionary is needed for decompression.booleanneedsInput()Returns true if no data remains in the input buffer.voidreset()Resets inflater so that a new set of input data can be processed.voidsetDictionary(byte[] dictionary)Sets the preset dictionary to the given array of bytes.voidsetDictionary(byte[] dictionary, int off, int len)Sets the preset dictionary to the given array of bytes.voidsetDictionary(ByteBuffer dictionary)Sets the preset dictionary to the bytes in the given buffer.voidsetInput(byte[] input)Sets input data for decompression.voidsetInput(byte[] input, int off, int len)Sets input data for decompression.voidsetInput(ByteBuffer input)Sets input data for decompression.
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Constructor Detail
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Inflater
public Inflater(boolean nowrap)
Creates a new decompressor. If the parameter 'nowrap' is true then the ZLIB header and checksum fields will not be used. This provides compatibility with the compression format used by both GZIP and PKZIP.Note: When using the 'nowrap' option it is also necessary to provide an extra "dummy" byte as input. This is required by the ZLIB native library in order to support certain optimizations.
- Parameters:
nowrap- if true then support GZIP compatible compression
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Inflater
public Inflater()
Creates a new decompressor.
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Method Detail
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setInput
public void setInput(byte[] input, int off, int len)Sets input data for decompression.One of the
setInput()methods should be called wheneverneedsInput()returns true indicating that more input data is required.- Parameters:
input- the input data bytesoff- the start offset of the input datalen- the length of the input data- See Also:
needsInput()
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setInput
public void setInput(byte[] input)
Sets input data for decompression.One of the
setInput()methods should be called wheneverneedsInput()returns true indicating that more input data is required.- Parameters:
input- the input data bytes- See Also:
needsInput()
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setInput
public void setInput(ByteBuffer input)
Sets input data for decompression.One of the
setInput()methods should be called wheneverneedsInput()returns true indicating that more input data is required.The given buffer's position will be advanced as inflate operations are performed, up to the buffer's limit. The input buffer may be modified (refilled) between inflate operations; doing so is equivalent to creating a new buffer and setting it with this method.
Modifying the input buffer's contents, position, or limit concurrently with an inflate operation will result in undefined behavior, which may include incorrect operation results or operation failure.
- Parameters:
input- the input data bytes- Since:
- 11
- See Also:
needsInput()
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setDictionary
public void setDictionary(byte[] dictionary, int off, int len)Sets the preset dictionary to the given array of bytes. Should be called when inflate() returns 0 and needsDictionary() returns true indicating that a preset dictionary is required. The method getAdler() can be used to get the Adler-32 value of the dictionary needed.- Parameters:
dictionary- the dictionary data bytesoff- the start offset of the datalen- the length of the data- See Also:
needsDictionary(),getAdler()
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setDictionary
public void setDictionary(byte[] dictionary)
Sets the preset dictionary to the given array of bytes. Should be called when inflate() returns 0 and needsDictionary() returns true indicating that a preset dictionary is required. The method getAdler() can be used to get the Adler-32 value of the dictionary needed.- Parameters:
dictionary- the dictionary data bytes- See Also:
needsDictionary(),getAdler()
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setDictionary
public void setDictionary(ByteBuffer dictionary)
Sets the preset dictionary to the bytes in the given buffer. Should be called when inflate() returns 0 and needsDictionary() returns true indicating that a preset dictionary is required. The method getAdler() can be used to get the Adler-32 value of the dictionary needed.The bytes in given byte buffer will be fully consumed by this method. On return, its position will equal its limit.
- Parameters:
dictionary- the dictionary data bytes- Since:
- 11
- See Also:
needsDictionary(),getAdler()
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getRemaining
public int getRemaining()
Returns the total number of bytes remaining in the input buffer. This can be used to find out what bytes still remain in the input buffer after decompression has finished.- Returns:
- the total number of bytes remaining in the input buffer
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needsInput
public boolean needsInput()
Returns true if no data remains in the input buffer. This can be used to determine if one of thesetInput()methods should be called in order to provide more input.- Returns:
- true if no data remains in the input buffer
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needsDictionary
public boolean needsDictionary()
Returns true if a preset dictionary is needed for decompression.- Returns:
- true if a preset dictionary is needed for decompression
- See Also:
setDictionary(byte[], int, int)
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finished
public boolean finished()
Returns true if the end of the compressed data stream has been reached.- Returns:
- true if the end of the compressed data stream has been reached
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inflate
public int inflate(byte[] output, int off, int len) throws DataFormatExceptionUncompresses bytes into specified buffer. Returns actual number of bytes uncompressed. A return value of 0 indicates that needsInput() or needsDictionary() should be called in order to determine if more input data or a preset dictionary is required. In the latter case, getAdler() can be used to get the Adler-32 value of the dictionary required.If the
setInput(ByteBuffer)method was called to provide a buffer for input, the input buffer's position will be advanced by the number of bytes consumed by this operation, even in the event that aDataFormatExceptionis thrown.The remaining byte count will be reduced by the number of consumed input bytes. If the
setInput(ByteBuffer)method was called to provide a buffer for input, the input buffer's position will be advanced the number of consumed bytes.These byte totals, as well as the total bytes read and the total bytes written values, will be updated even in the event that a
DataFormatExceptionis thrown to reflect the amount of data consumed and produced before the exception occurred.- Parameters:
output- the buffer for the uncompressed dataoff- the start offset of the datalen- the maximum number of uncompressed bytes- Returns:
- the actual number of uncompressed bytes
- Throws:
DataFormatException- if the compressed data format is invalid- See Also:
needsInput(),needsDictionary()
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inflate
public int inflate(byte[] output) throws DataFormatExceptionUncompresses bytes into specified buffer. Returns actual number of bytes uncompressed. A return value of 0 indicates that needsInput() or needsDictionary() should be called in order to determine if more input data or a preset dictionary is required. In the latter case, getAdler() can be used to get the Adler-32 value of the dictionary required.The remaining byte count will be reduced by the number of consumed input bytes. If the
setInput(ByteBuffer)method was called to provide a buffer for input, the input buffer's position will be advanced the number of consumed bytes.These byte totals, as well as the total bytes read and the total bytes written values, will be updated even in the event that a
DataFormatExceptionis thrown to reflect the amount of data consumed and produced before the exception occurred.- Parameters:
output- the buffer for the uncompressed data- Returns:
- the actual number of uncompressed bytes
- Throws:
DataFormatException- if the compressed data format is invalid- See Also:
needsInput(),needsDictionary()
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inflate
public int inflate(ByteBuffer output) throws DataFormatException
Uncompresses bytes into specified buffer. Returns actual number of bytes uncompressed. A return value of 0 indicates that needsInput() or needsDictionary() should be called in order to determine if more input data or a preset dictionary is required. In the latter case, getAdler() can be used to get the Adler-32 value of the dictionary required.On success, the position of the given
outputbyte buffer will be advanced by as many bytes as were produced by the operation, which is equal to the number returned by this method. Note that the position of theoutputbuffer will be advanced even in the event that aDataFormatExceptionis thrown.The remaining byte count will be reduced by the number of consumed input bytes. If the
setInput(ByteBuffer)method was called to provide a buffer for input, the input buffer's position will be advanced the number of consumed bytes.These byte totals, as well as the total bytes read and the total bytes written values, will be updated even in the event that a
DataFormatExceptionis thrown to reflect the amount of data consumed and produced before the exception occurred.- Parameters:
output- the buffer for the uncompressed data- Returns:
- the actual number of uncompressed bytes
- Throws:
DataFormatException- if the compressed data format is invalidReadOnlyBufferException- if the given output buffer is read-only- Since:
- 11
- See Also:
needsInput(),needsDictionary()
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getAdler
public int getAdler()
Returns the ADLER-32 value of the uncompressed data.- Returns:
- the ADLER-32 value of the uncompressed data
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getTotalIn
public int getTotalIn()
Returns the total number of compressed bytes input so far.Since the number of bytes may be greater than Integer.MAX_VALUE, the
getBytesRead()method is now the preferred means of obtaining this information.- Returns:
- the total number of compressed bytes input so far
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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
- Since:
- 1.5
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getTotalOut
public int getTotalOut()
Returns the total number of uncompressed bytes output so far.Since the number of bytes may be greater than Integer.MAX_VALUE, the
getBytesWritten()method is now the preferred means of obtaining this information.- Returns:
- the total number of uncompressed bytes output so far
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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
- Since:
- 1.5
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reset
public void reset()
Resets inflater so that a new set of input data can be processed.
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end
public void end()
Closes the decompressor and discards any unprocessed input. This method should be called when the decompressor is no longer being used. Once this method is called, the behavior of the Inflater object is undefined.
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finalize
@Deprecated(since="9", forRemoval=true) protected void finalize()
Deprecated, for removal: This API element is subject to removal in a future version.Thefinalizemethod has been deprecated and will be removed. It is implemented as a no-op. Subclasses that overridefinalizein order to perform cleanup should be modified to use alternative cleanup mechanisms and remove the overridingfinalizemethod. The recommended cleanup for compressor is to explicitly callendmethod when it is no longer in use. If theendis not invoked explicitly the resource of the compressor will be released when the instance becomes unreachable,Closes the decompressor when garbage is collected.- Overrides:
finalizein classObject- Implementation Requirements:
- If this
Inflaterhas been subclassed and theendmethod has been overridden, theendmethod will be called when the inflater is unreachable. - See Also:
WeakReference,PhantomReference
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