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

Class GzipCompressorInputStream

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable, InputStreamStatistics
    public class GzipCompressorInputStream
extends CompressorInputStream
implements InputStreamStatistics
    Input stream that decompresses GZIP (.gz) files.

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

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

    If you use the constructor GzipCompressorInputStream(in), Builder.setDecompressConcatenated(false), 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 Builder.setDecompressConcatenated(true) or 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.

    To build an instance, use GzipCompressorInputStream.Builder.

    See Also:
    GzipCompressorInputStream.Builder, RFC 1952 GZIP File Format Specification

    • 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

        @Deprecated
public GzipCompressorInputStream​(java.io.InputStream inputStream,
                                 boolean decompressConcatenated)
                          throws java.io.IOException
        Deprecated.
        Use GzipCompressorInputStream.Builder.get().
        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

      • 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

      • 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 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