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