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:

Closeable, 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"

Constructor Summary

Constructors

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

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, read, reset, skip

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

Constructor Details

GzipCompressorInputStream

public GzipCompressorInputStream(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 - the InputStream from which this object should be created of

Throws:

IOException - if the stream could not be created

GzipCompressorInputStream

public GzipCompressorInputStream(InputStream inputStream,
 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 - 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:

IOException - if the stream could not be created

Method Details

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

close

public void close()
           throws IOException

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

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class InputStream

Throws:

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

read

public int read()
         throws IOException

Specified by:

read in class InputStream

Throws:

IOException

read

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

Overrides:

read in class InputStream

Throws:

IOException

Since:

1.1