Package org.apache.commons.compress.compressors.snappy

Class SnappyCompressorOutputStream

  • All Implemented Interfaces:
    java.io.Closeable, java.io.Flushable, java.lang.AutoCloseable
    public class SnappyCompressorOutputStream
extends CompressorOutputStream
    CompressorOutputStream for the raw Snappy format.

    This implementation uses an internal buffer in order to handle the back-references that are at the heart of the LZ77 algorithm. The size of the buffer must be at least as big as the biggest offset used in the compressed stream. The current version of the Snappy algorithm as defined by Google works on 32k blocks and doesn't contain offsets bigger than 32k which is the default block size used by this class.

    The raw Snappy format requires the uncompressed size to be written at the beginning of the stream using a varint representation, i.e. the number of bytes needed to write the information is not known before the uncompressed size is known. We've chosen to make the uncompressedSize a parameter of the constructor in favor of buffering the whole output until the size is known. When using the FramedSnappyCompressorOutputStream this limitation is taken care of by the warpping framing format.

    Since:
    1.14
    See Also:
    Snappy compressed format description

    • Constructor Summary

      Constructors 
      Constructor Description
      SnappyCompressorOutputStream​(java.io.OutputStream os, long uncompressedSize)
      Constructor using the default block size of 32k.
      SnappyCompressorOutputStream​(java.io.OutputStream os, long uncompressedSize, int blockSize)
      Constructor using a configurable block size.
      SnappyCompressorOutputStream​(java.io.OutputStream os, long uncompressedSize, Parameters params)
      Constructor providing full control over the underlying LZ77 compressor.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void close()  
      static Parameters.Builder createParameterBuilder​(int blockSize)
      Returns a builder correctly configured for the Snappy algorithm using the gven block size.
      void finish()
      Compresses all remaining data and writes it to the stream, doesn't close the underlying stream.
      void write​(byte[] data, int off, int len)  
      void write​(int b)  

      • Methods inherited from class java.io.OutputStream

        flush, nullOutputStream, write

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • SnappyCompressorOutputStream

        public SnappyCompressorOutputStream​(java.io.OutputStream os,
                                    long uncompressedSize)
                             throws java.io.IOException
        Constructor using the default block size of 32k.
        Parameters:
        os - the outputstream to write compressed data to
        uncompressedSize - the uncompressed size of data
        Throws:
        java.io.IOException - if writing of the size fails

      • SnappyCompressorOutputStream

        public SnappyCompressorOutputStream​(java.io.OutputStream os,
                                    long uncompressedSize,
                                    int blockSize)
                             throws java.io.IOException
        Constructor using a configurable block size.
        Parameters:
        os - the outputstream to write compressed data to
        uncompressedSize - the uncompressed size of data
        blockSize - the block size used - must be a power of two
        Throws:
        java.io.IOException - if writing of the size fails

      • SnappyCompressorOutputStream

        public SnappyCompressorOutputStream​(java.io.OutputStream os,
                                    long uncompressedSize,
                                    Parameters params)
                             throws java.io.IOException
        Constructor providing full control over the underlying LZ77 compressor.
        Parameters:
        os - the outputstream to write compressed data to
        uncompressedSize - the uncompressed size of data
        params - the parameters to use by the compressor - note that the format itself imposes some limits like a maximum match length of 64 bytes
        Throws:
        java.io.IOException - if writing of the size fails

    • Method Detail

      • write

        public void write​(int b)
           throws java.io.IOException
        Specified by:
        write in class java.io.OutputStream
        Throws:
        java.io.IOException

      • write

        public void write​(byte[] data,
                  int off,
                  int len)
           throws java.io.IOException
        Overrides:
        write in class java.io.OutputStream
        Throws:
        java.io.IOException

      • close

        public void close()
           throws java.io.IOException
        Specified by:
        close in interface java.lang.AutoCloseable
        Specified by:
        close in interface java.io.Closeable
        Overrides:
        close in class java.io.OutputStream
        Throws:
        java.io.IOException

      • finish

        public void finish()
            throws java.io.IOException
        Compresses all remaining data and writes it to the stream, doesn't close the underlying stream.
        Throws:
        java.io.IOException - if an error occurs

      • createParameterBuilder

        public static Parameters.Builder createParameterBuilder​(int blockSize)
        Returns a builder correctly configured for the Snappy algorithm using the gven block size.
        Parameters:
        blockSize - the block size.
        Returns:
        a builder correctly configured for the Snappy algorithm using the gven block size