net.jpountz.lz4

Class LZ4CompressorWithLength

java.lang.Object

net.jpountz.lz4.LZ4CompressorWithLength

public class LZ4CompressorWithLength
extends java.lang.Object

Covenience class to include the length of the original decompressed data in the output compressed data, so that the user does not need to save the length at anywhere else. The compressed data must be decompressed by LZ4DecompressorWithLength and is NOT compatible with any other decompressors in lz4-java or any other lz4 tools. This class deliberately does not extend LZ4Compressor because they are not interchangable.

Constructor Summary

Constructors

Constructor and Description
LZ4CompressorWithLength(LZ4Compressor compressor) Creates a new compressor that includes the length of the original decompressed data in the output compressed data.

Method Summary

Modifier and Type	Method and Description
byte[]	compress(byte[] src) Convenience method, equivalent to calling compress(src, 0, src.length).
int	compress(byte[] src, byte[] dest) Convenience method, equivalent to calling compress(src, 0, src.length, dest, 0).
byte[]	compress(byte[] src, int srcOff, int srcLen) Convenience method which returns src[srcOff:srcOff+srcLen] compressed.
int	compress(byte[] src, int srcOff, int srcLen, byte[] dest, int destOff) Convenience method, equivalent to calling compress(src, srcOff, srcLen, dest, destOff, dest.length - destOff).
int	compress(byte[] src, int srcOff, int srcLen, byte[] dest, int destOff, int maxDestLen) Compresses src[srcOff:srcOff+srcLen] into dest[destOff:destOff+maxDestLen] and returns the compressed length.
void	compress(java.nio.ByteBuffer src, java.nio.ByteBuffer dest) Compresses src into dest.
int	compress(java.nio.ByteBuffer src, int srcOff, int srcLen, java.nio.ByteBuffer dest, int destOff, int maxDestLen) Compresses src[srcOff:srcOff+srcLen] into dest[destOff:destOff+maxDestLen] and returns the compressed length.
int	maxCompressedLength(int length) Returns the maximum compressed length for an input of size length.

Methods inherited from class java.lang.Object

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

Constructor Detail

LZ4CompressorWithLength

public LZ4CompressorWithLength(LZ4Compressor compressor)

Creates a new compressor that includes the length of the original decompressed data in the output compressed data.

Parameters:

compressor - compressor to use

Method Detail

maxCompressedLength

public int maxCompressedLength(int length)

Returns the maximum compressed length for an input of size length.

Parameters:

length - the input size in bytes

Returns:

the maximum compressed length in bytes

compress

public byte[] compress(byte[] src)

Convenience method, equivalent to calling compress(src, 0, src.length).

Parameters:

src - the source data

Returns:

the compressed data

compress

public byte[] compress(byte[] src,
                       int srcOff,
                       int srcLen)

Convenience method which returns src[srcOff:srcOff+srcLen] compressed.

Warning: this method has an important overhead due to the fact that it needs to allocate a buffer to compress into, and then needs to resize this buffer to the actual compressed length.

Here is how this method is implemented:

 final int maxCompressedLength = maxCompressedLength(srcLen);
 final byte[] compressed = new byte[maxCompressedLength];
 final int compressedLength = compress(src, srcOff, srcLen, compressed, 0);
 return Arrays.copyOf(compressed, compressedLength);
 

Parameters:

src - the source data

srcOff - the start offset in src

srcLen - the number of bytes to compress

Returns:

the compressed data

compress

public int compress(byte[] src,
                    byte[] dest)

Convenience method, equivalent to calling compress(src, 0, src.length, dest, 0).

Parameters:

src - the source data

dest - the destination buffer

Returns:

the compressed size

Throws:

LZ4Exception - if dest is too small

compress

public int compress(byte[] src,
                    int srcOff,
                    int srcLen,
                    byte[] dest,
                    int destOff)

Convenience method, equivalent to calling compress(src, srcOff, srcLen, dest, destOff, dest.length - destOff).

Parameters:

src - the source data

srcOff - the start offset in src

srcLen - the number of bytes to compress

dest - the destination buffer

destOff - the start offset in dest

Returns:

the compressed size

Throws:

LZ4Exception - if dest is too small

compress

public int compress(byte[] src,
                    int srcOff,
                    int srcLen,
                    byte[] dest,
                    int destOff,
                    int maxDestLen)

Compresses src[srcOff:srcOff+srcLen] into dest[destOff:destOff+maxDestLen] and returns the compressed length. This method will throw a LZ4Exception if this compressor is unable to compress the input into less than maxDestLen bytes. To prevent this exception to be thrown, you should make sure that maxDestLen >= maxCompressedLength(srcLen).

Parameters:

src - the source data

srcOff - the start offset in src

srcLen - the number of bytes to compress

dest - the destination buffer

destOff - the start offset in dest

maxDestLen - the maximum number of bytes to write in dest

Returns:

the compressed size

Throws:

LZ4Exception - if maxDestLen is too small

compress

public void compress(java.nio.ByteBuffer src,
                     java.nio.ByteBuffer dest)

Compresses src into dest. Calling this method will update the positions of both ByteBuffers.

Parameters:

src - the source data

dest - the destination buffer

Throws:

LZ4Exception - if dest is too small

compress

public int compress(java.nio.ByteBuffer src,
                    int srcOff,
                    int srcLen,
                    java.nio.ByteBuffer dest,
                    int destOff,
                    int maxDestLen)

Compresses src[srcOff:srcOff+srcLen] into dest[destOff:destOff+maxDestLen] and returns the compressed length. This method will throw a LZ4Exception if this compressor is unable to compress the input into less than maxDestLen bytes. To prevent this exception to be thrown, you should make sure that maxDestLen >= maxCompressedLength(srcLen). ByteBuffer positions remain unchanged.

Parameters:

src - the source data

srcOff - the start offset in src

srcLen - the number of bytes to compress

dest - the destination buffer

destOff - the start offset in dest

maxDestLen - the maximum number of bytes to write in dest

Returns:

the compressed size

Throws:

LZ4Exception - if maxDestLen is too small