Package org.apache.hadoop.io.compress.zlib

Class BuiltInGzipDecompressor

java.lang.Object
org.apache.hadoop.io.compress.zlib.BuiltInGzipDecompressor
All Implemented Interfaces:
Decompressor
@DoNotPool public class BuiltInGzipDecompressor extends Object implements Decompressor
A Decompressor based on the popular gzip compressed file format. http://www.gzip.org/

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static enum 
    BuiltInGzipDecompressor.GzipStateLabel
    The current state of the gzip decoder, external to the Inflater context.

  • Constructor Summary

    Constructors
    Constructor
    Description
    BuiltInGzipDecompressor()
    Creates a new (pure Java) gzip decompressor.

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    decompress(byte[] b, int off, int len)
    Decompress the data (gzip header, deflate stream, gzip trailer) in the provided buffer.
    void
    end()
    Closes the decompressor and discards any unprocessed input.
    boolean
    finished()
    Returns true if the end of the gzip substream (single "member") has been reached.
    long
    getBytesRead()
    Returns the total number of compressed bytes input so far, including gzip header/trailer bytes.
    int
    getRemaining()
    Returns the number of bytes remaining in the input buffer; normally called when finished() is true to determine amount of post-gzip-stream data.
    boolean
    needsDictionary()
    Returns true if a preset dictionary is needed for decompression.
    boolean
    needsInput()
    Returns true if the input data buffer is empty and Decompressor.setInput(byte[], int, int) should be called to provide more input.
    void
    reset()
    Resets everything, including the input buffer, regardless of whether the current gzip substream is finished.
    void
    setDictionary(byte[] b, int off, int len)
    Sets preset dictionary for compression.
    void
    setInput(byte[] b, int off, int len)
    Sets input data for decompression.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • BuiltInGzipDecompressor

      public BuiltInGzipDecompressor()
      Creates a new (pure Java) gzip decompressor.

  • Method Details

    • needsInput

      public boolean needsInput()
      Description copied from interface: Decompressor
      Returns true if the input data buffer is empty and Decompressor.setInput(byte[], int, int) should be called to provide more input.
      Specified by:
      needsInput in interface Decompressor
      Returns:
      true if the input data buffer is empty and Decompressor.setInput(byte[], int, int) should be called in order to provide more input.

    • setInput

      public void setInput(byte[] b, int off, int len)
      Sets input data for decompression. This should be called if and only if Decompressor.needsInput() returns true indicating that more input data is required. (Both native and non-native versions of various Decompressors require that the data passed in via b[] remain unmodified until the caller is explicitly notified--via Decompressor.needsInput()--that the buffer may be safely modified. With this requirement, an extra buffer-copy can be avoided.)
      Specified by:
      setInput in interface Decompressor
      Parameters:
      b - Input data
      off - Start offset
      len - Length

    • decompress

      public int decompress(byte[] b, int off, int len) throws IOException
      Decompress the data (gzip header, deflate stream, gzip trailer) in the provided buffer.
      Specified by:
      decompress in interface Decompressor
      Parameters:
      b - Buffer for the uncompressed data
      off - Start offset of the data
      len - Size of the buffer
      Returns:
      the number of decompressed bytes placed into b
      Throws:
      IOException - raised on errors performing I/O.

    • getBytesRead

      public long getBytesRead()
      Returns the total number of compressed bytes input so far, including gzip header/trailer bytes.
      Returns:
      the total (non-negative) number of compressed bytes read so far

    • getRemaining

      public int getRemaining()
      Returns the number of bytes remaining in the input buffer; normally called when finished() is true to determine amount of post-gzip-stream data. Note that, other than the finished state with concatenated data after the end of the current gzip stream, this will never return a non-zero value unless called after setInput(byte[] b, int off, int len) and before decompress(byte[] b, int off, int len). (That is, after decompress(byte[] b, int off, int len) it always returns zero, except in finished state with concatenated data.)
      Specified by:
      getRemaining in interface Decompressor
      Returns:
      the total (non-negative) number of unprocessed bytes in input

    • needsDictionary

      public boolean needsDictionary()
      Description copied from interface: Decompressor
      Returns true if a preset dictionary is needed for decompression.
      Specified by:
      needsDictionary in interface Decompressor
      Returns:
      true if a preset dictionary is needed for decompression

    • setDictionary

      public void setDictionary(byte[] b, int off, int len)
      Description copied from interface: Decompressor
      Sets preset dictionary for compression. A preset dictionary is used when the history buffer can be predetermined.
      Specified by:
      setDictionary in interface Decompressor
      Parameters:
      b - Dictionary data bytes
      off - Start offset
      len - Length

    • finished

      public boolean finished()
      Returns true if the end of the gzip substream (single "member") has been reached.
      Specified by:
      finished in interface Decompressor
      Returns:
      true if the end of the decompressed data output stream has been reached.

    • reset

      public void reset()
      Resets everything, including the input buffer, regardless of whether the current gzip substream is finished.
      Specified by:
      reset in interface Decompressor

    • end

      public void end()
      Description copied from interface: Decompressor
      Closes the decompressor and discards any unprocessed input.
      Specified by:
      end in interface Decompressor