Apache Commons Compress 1.26.0 · org.apache.commons.compress.compressors.gzip.GzipCompressorInputStream

Input stream that decompresses .gz files.

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

java.util.zip.GZIPInputStream doesn't decompress concatenated .gz files: it stops after the first member and silently ignores the rest. It doesn't leave the read position to point to the beginning of the next member, which makes it difficult workaround the lack of concatenation support.

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

If you use the constructor GzipCompressorInputStream(in) or GzipCompressorInputStream(in, false) with some InputStream in then read will return -1 as soon as the first internal member has been read completely. The stream in will be positioned at the start of the second gzip member if there is one.

If you use the constructor GzipCompressorInputStream(in, true) with some InputStream in then read will return -1 once the stream in has been exhausted. The data read from a stream constructed this way will consist of the concatenated data of all gzip members contained inside in.

Field Summary

Modifier and Type	Field and Description
private final byte[]	buf
private int	bufUsed
private final CountingInputStream	countingStream
private final CRC32	crc
private final boolean	decompressConcatenated
private boolean	endReached
private static final int	FCOMMENT
private static final int	FEXTRA
private static final int	FHCRC
private static final int	FNAME
private static final int	FRESERVED
private final InputStream	in
private Inflater	inf
private final byte[]	oneByte
private final GzipParameters	parameters

Constructor Summary

Access	Constructor and Description
public	GzipCompressorInputStream(final InputStream the InputStream from which this object should be created of inputStream) Constructs a new input stream that decompresses gzip-compressed data from the specified input stream.
public	GzipCompressorInputStream(final InputStream the InputStream from which this object should be created of inputStream, final boolean if true, decompress until the end of the input; if false, stop after the first .gz member decompressConcatenated) Constructs a new input stream that decompresses gzip-compressed data from the specified input stream.

Method Summary

Modifier and Type	Method and Description
public void	close() Overrides java.io.InputStream.close. Implements java.io.Closeable.close. Closes the input stream (unless it is System.in).
public long	getCompressedCount() Implements org.apache.commons.compress.utils.InputStreamStatistics.getCompressedCount. Gets the amount of raw or compressed bytes read by the stream.
public GzipParameters	Returns: the stream's meta data getMetaData() Provides the stream's meta data - may change with each stream when decompressing concatenated streams.
private boolean	init(final boolean isFirstMember)
public static boolean	Returns: true if this is a .gz stream, false otherwise matches(final byte[] the bytes to check signature, final int the number of bytes to check length) Checks if the signature matches what is expected for a .gz file.
public int	read() Implements abstract java.io.InputStream.read. Reads the next byte of data from the input stream.
public int	read(final byte[] the buffer into which the data is read. b, int the start offset in array `b` at which the data is written. off, int the maximum number of bytes to read. len) Overrides java.io.InputStream.read. Reads up to `len` bytes of data from the input stream into an array of bytes.
private static byte[]	readToNull(final DataInput inData)

Inherited from org.apache.commons.compress.compressors.CompressorInputStream:: count count getBytesRead getCount getUncompressedCount pushedBackBytes

Field Detail

buf	back to summary
private final byte[] buf

bufUsed	back to summary
private int bufUsed

countingStream	back to summary
private final CountingInputStream countingStream

crc	back to summary
private final CRC32 crc

decompressConcatenated	back to summary
private final boolean decompressConcatenated

endReached	back to summary
private boolean endReached

FCOMMENT	back to summary
private static final int FCOMMENT

FEXTRA	back to summary
private static final int FEXTRA

FHCRC	back to summary
private static final int FHCRC

FNAME	back to summary
private static final int FNAME

FRESERVED	back to summary
private static final int FRESERVED

in	back to summary
private final InputStream in

inf	back to summary
private Inflater inf

oneByte	back to summary
private final byte[] oneByte

parameters	back to summary
private final GzipParameters parameters

Constructor Detail

GzipCompressorInputStream back to summary

GzipCompressorInputStream	back to summary
public GzipCompressorInputStream(final InputStream inputStream) throws 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:InputStream the InputStream from which this object should be created of Exceptions IOException: if the stream could not be created

public GzipCompressorInputStream(final InputStream inputStream) throws 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:InputStream: the InputStream from which this object should be created of

Exceptions

IOException:: if the stream could not be created

GzipCompressorInputStream back to summary

GzipCompressorInputStream	back to summary
public GzipCompressorInputStream(final InputStream inputStream, final boolean decompressConcatenated) throws 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:InputStream the InputStream from which this object should be created of decompressConcatenated:boolean if true, decompress until the end of the input; if false, stop after the first .gz member Exceptions IOException: if the stream could not be created

public GzipCompressorInputStream(final InputStream inputStream, final boolean decompressConcatenated) throws 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:InputStream: the InputStream from which this object should be created of
decompressConcatenated:boolean: if true, decompress until the end of the input; if false, stop after the first .gz member

Exceptions

IOException:: if the stream could not be created

Method Detail

close	back to summary
public void close() throws IOException Overrides java.io.InputStream.close. Implements java.io.Closeable.close. Closes the input stream (unless it is System.in). Annotations @Override Exceptions IOException: Doc from java.io.InputStream.close. if an I/O error occurs. Since 1.2

back to summary

public void close() throws IOException

Overrides java.io.InputStream.close.

Implements java.io.Closeable.close.

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

Annotations

@Override

Exceptions

IOException:

Doc from java.io.InputStream.close.

if an I/O error occurs.

Since

1.2

getCompressedCount	back to summary
public long getCompressedCount() Implements org.apache.commons.compress.utils.InputStreamStatistics.getCompressedCount. Doc from org.apache.commons.compress.utils.InputStreamStatistics.getCompressedCount. Gets the amount of raw or compressed bytes read by the stream. Returns:long the amount of raw or compressed bytes read by the stream. Annotations @Override Since 1.17

getCompressedCount

back to summary

public long getCompressedCount()

Implements org.apache.commons.compress.utils.InputStreamStatistics.getCompressedCount.

Doc from org.apache.commons.compress.utils.InputStreamStatistics.getCompressedCount.

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

Returns:long

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

Annotations

@Override

Since

1.17

getMetaData

back to summary

public GzipParameters getMetaData()

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

Returns:GzipParameters: the stream's meta data
Since: 1.8

init	back to summary
private boolean init(final boolean isFirstMember) throws IOException

matches	back to summary
public static boolean matches(final byte[] signature, final int length) Checks if the signature matches what is expected for a .gz file. Parameters signature:byte[] the bytes to check length:int the number of bytes to check Returns:boolean true if this is a .gz stream, false otherwise Since 1.1

matches

back to summary

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

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

Parameters

signature:byte[]: the bytes to check
length:int: the number of bytes to check

Returns:boolean

true if this is a .gz stream, false otherwise

Since

1.1

read back to summary

read	back to summary
public int read() throws IOException Implements abstract java.io.InputStream.read. Doc from java.io.InputStream.read. Reads the next byte of data from the input stream. The value byte is returned as an `int` in the range `0` to `255`. If no byte is available because the end of the stream has been reached, the value `-1` is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown. Returns:int the next byte of data, or `-1` if the end of the stream is reached. Annotations @Override Exceptions IOException: if an I/O error occurs.

public int read() throws IOException

Implements abstract java.io.InputStream.read.

Doc from java.io.InputStream.read.

Reads the next byte of data from the input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

Returns:int

the next byte of data, or -1 if the end of the stream is reached.

Annotations

@Override

Exceptions

IOException:: if an I/O error occurs.

read back to summary

read	back to summary
public int read(final byte[] b, int off, int len) throws IOException Overrides java.io.InputStream.read. Doc from java.io.InputStream.read. Reads up to `len` bytes of data from the input stream into an array of bytes. An attempt is made to read as many as `len` bytes, but a smaller number may be read. The number of bytes actually read is returned as an integer. This method blocks until input data is available, end of file is detected, or an exception is thrown. If `len` is zero, then no bytes are read and `0` is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value `-1` is returned; otherwise, at least one byte is read and stored into `b`. The first byte read is stored into element `b[off]`, the next one into `b[off+1]`, and so on. The number of bytes read is, at most, equal to `len`. Let k be the number of bytes actually read; these bytes will be stored in elements `b[off]` through `b[off+`k`-1]`, leaving elements `b[off+`k`]` through `b[off+len-1]` unaffected. In every case, elements `b[0]` through `b[off-1]` and elements `b[off+len]` through `b[b.length-1]` are unaffected. Parameters b:byte[] the buffer into which the data is read. off:int the start offset in array `b` at which the data is written. len:int the maximum number of bytes to read. Returns:int the total number of bytes read into the buffer, or `-1` if there is no more data because the end of the stream has been reached. Annotations @Override Exceptions IOException: If the first byte cannot be read for any reason other than end of file, or if the input stream has been closed, or if some other I/O error occurs. Since 1.1

public int read(final byte[] b, int off, int len) throws IOException

Overrides java.io.InputStream.read.

Doc from java.io.InputStream.read.

Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read. The number of bytes actually read is returned as an integer.

This method blocks until input data is available, end of file is detected, or an exception is thrown.

If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.

In every case, elements b[0] through b[off-1] and elements b[off+len] through b[b.length-1] are unaffected.

Parameters

b:byte[]: the buffer into which the data is read.
off:int: the start offset in array b at which the data is written.
len:int: the maximum number of bytes to read.

Returns:int

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Annotations

@Override

Exceptions

IOException:: If the first byte cannot be read for any reason other than end of file, or if the input stream has been closed, or if some other I/O error occurs.

Since

1.1

readToNull	back to summary
private static byte[] readToNull(final DataInput inData) throws IOException

public Class GzipCompressorInputStream

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail