Package org.apache.commons.compress.compressors.gzip

Class GzipCompressorInputStream

java.lang.Object

java.io.InputStream

org.apache.commons.compress.compressors.CompressorInputStream

org.apache.commons.compress.compressors.gzip.GzipCompressorInputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, InputStreamStatistics

public class GzipCompressorInputStream
extends CompressorInputStream
implements InputStreamStatistics

Input stream that decompresses .gz files.

This supports decompressing concatenated .gz files which is important when decompressing standalone .gz files.

Instead of using java.util.zip.GZIPInputStream, this class has its own GZIP member decoder. The actual decompression is done with Inflater.

If you use the constructor GzipCompressorInputStream(in) or GzipCompressorInputStream(in, false), then read() will return -1 as soon as the first encoded GZIP member has been completely read. In this case, if the underlying input stream supports mark() and reset(), then it will be left positioned just after the end of the encoded GZIP member; otherwise, some indeterminate number of extra bytes following the encoded GZIP member will have been consumed and discarded.

If you use the constructor GzipCompressorInputStream(in, true) then read() will return -1 only after the entire input stream has been exhausted; any bytes that follow an encoded GZIP member must constitute a new encoded GZIP member, otherwise an IOException is thrown. The data read from a stream constructed this way will consist of the concatenated data of all of the encoded GZIP members in order.

See Also:

"https://tools.ietf.org/html/rfc1952"

Field Summary

Fields

Modifier and Type	Field	Description
private byte[]	buf
private int	bufUsed
private org.apache.commons.io.input.BoundedInputStream	countingStream
private java.util.zip.CRC32	crc
private boolean	decompressConcatenated
private boolean	endReached
private static int	FCOMMENT
private static int	FEXTRA
private static int	FHCRC
private static int	FNAME
private static int	FRESERVED
private java.io.InputStream	in
private java.util.zip.Inflater	inf
private byte[]	oneByte
private GzipParameters	parameters

Constructor Summary

Constructors

Constructor	Description
GzipCompressorInputStream(java.io.InputStream inputStream)	Constructs a new input stream that decompresses gzip-compressed data from the specified input stream.
GzipCompressorInputStream(java.io.InputStream inputStream, boolean decompressConcatenated)	Constructs a new input stream that decompresses gzip-compressed data from the specified input stream.

Method Summary

Modifier and Type	Method	Description
void	close()	Closes the input stream (unless it is System.in).
long	getCompressedCount()	Gets the amount of raw or compressed bytes read by the stream.
GzipParameters	getMetaData()	Provides the stream's meta data - may change with each stream when decompressing concatenated streams.
private boolean	init(boolean isFirstMember)
static boolean	matches(byte[] signature, int length)	Checks if the signature matches what is expected for a .gz file.
int	read()
int	read(byte[] b, int off, int len)
private static byte[]	readToNull(java.io.DataInput inData)

Methods inherited from class org.apache.commons.compress.compressors.CompressorInputStream

count, count, getBytesRead, getCount, getUncompressedCount, pushedBackBytes

Methods inherited from class java.io.InputStream

available, mark, markSupported, nullInputStream, read, readAllBytes, readNBytes, readNBytes, reset, skip, transferTo

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.commons.compress.utils.InputStreamStatistics

getUncompressedCount

Field Detail

FHCRC

private static final int FHCRC

See Also:

Constant Field Values

FEXTRA

private static final int FEXTRA

See Also:

Constant Field Values

FNAME

private static final int FNAME

See Also:

Constant Field Values

FCOMMENT

private static final int FCOMMENT

See Also:

Constant Field Values

FRESERVED

private static final int FRESERVED

See Also:

Constant Field Values

countingStream

private final org.apache.commons.io.input.BoundedInputStream countingStream

in

private final java.io.InputStream in

decompressConcatenated

private final boolean decompressConcatenated

buf

private final byte[] buf

bufUsed

private int bufUsed

inf

private java.util.zip.Inflater inf

crc

private final java.util.zip.CRC32 crc

endReached

private boolean endReached

oneByte

private final byte[] oneByte

parameters

private final GzipParameters parameters

Constructor Detail

GzipCompressorInputStream

public GzipCompressorInputStream(java.io.InputStream inputStream)
                          throws java.io.IOException

Constructs a new input stream that decompresses gzip-compressed data from the specified input stream.

This is equivalent to GzipCompressorInputStream(inputStream, false) and thus will not decompress concatenated .gz files.

Parameters:

inputStream - the InputStream from which this object should be created of

Throws:

java.io.IOException - if the stream could not be created

GzipCompressorInputStream

public GzipCompressorInputStream(java.io.InputStream inputStream,
                                 boolean decompressConcatenated)
                          throws java.io.IOException

Constructs a new input stream that decompresses gzip-compressed data from the specified input stream.

If decompressConcatenated is false: This decompressor might read more input than it will actually use. If inputStream supports mark and reset, then the input position will be adjusted so that it is right after the last byte of the compressed stream. If mark isn't supported, the input position will be undefined.

Parameters:

inputStream - the InputStream from which this object should be created of

decompressConcatenated - if true, decompress until the end of the input; if false, stop after the first .gz member

Throws:

java.io.IOException - if the stream could not be created

Method Detail

matches

public static boolean matches(byte[] signature,
                              int length)

Checks if the signature matches what is expected for a .gz file.

Parameters:

signature - the bytes to check

length - the number of bytes to check

Returns:

true if this is a .gz stream, false otherwise

Since:

1.1

readToNull

private static byte[] readToNull(java.io.DataInput inData)
                          throws java.io.IOException

Throws:

java.io.IOException

close

public void close()
           throws java.io.IOException

Closes the input stream (unless it is System.in).

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

Overrides:

close in class java.io.InputStream

Throws:

java.io.IOException

Since:

1.2

getCompressedCount

public long getCompressedCount()

Description copied from interface: InputStreamStatistics

Gets the amount of raw or compressed bytes read by the stream.

Specified by:

getCompressedCount in interface InputStreamStatistics

Returns:

the amount of raw or compressed bytes read by the stream.

Since:

1.17

getMetaData

public GzipParameters getMetaData()

Provides the stream's meta data - may change with each stream when decompressing concatenated streams.

Returns:

the stream's meta data

Since:

1.8

init

private boolean init(boolean isFirstMember)
              throws java.io.IOException

Throws:

java.io.IOException

read

public int read()
         throws java.io.IOException

Specified by:

read in class java.io.InputStream

Throws:

java.io.IOException

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException

Overrides:

read in class java.io.InputStream

Throws:

java.io.IOException

Since:

1.1