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snappy-java is a Java port of the snappy, a fast C++ compresser/decompresser developed by Google.

Features

Performance

Download

Maven Central Javadoc

The current stable version is available from here:

Using with Maven

Snappy-java is available from Maven's central repository. Add the following dependency to your pom.xml:

<dependency>
  <groupId>org.xerial.snappy</groupId>
  <artifactId>snappy-java</artifactId>
  <version>(version)</version>
  <type>jar</type>
  <scope>compile</scope>
</dependency>

Using with sbt

libraryDependencies += "org.xerial.snappy" % "snappy-java" % "(version)"

Usage

First, import org.xerial.snapy.Snappy in your Java code:

import org.xerial.snappy.Snappy;

Then use Snappy.compress(byte[]) and Snappy.uncompress(byte[]):

String input = "Hello snappy-java! Snappy-java is a JNI-based wrapper of "
     + "Snappy, a fast compresser/decompresser.";
byte[] compressed = Snappy.compress(input.getBytes("UTF-8"));
byte[] uncompressed = Snappy.uncompress(compressed);

String result = new String(uncompressed, "UTF-8");
System.out.println(result);

In addition, high-level methods (Snappy.compress(String), Snappy.compress(float[] ..) etc. ) and low-level ones (e.g. Snappy.rawCompress(.. ), Snappy.rawUncompress(..), etc.), which minimize memory copies, can be used.

Stream-based API

Stream-based compressor/decompressor SnappyOutputStream/SnappyInputStream are also available for reading/writing large data sets. SnappyFramedOutputStream/SnappyFramedInputStream can be used for the framing format.

Compatibility Notes

The original Snappy format definition did not define a file format. It later added a "framing" format to define a file format, but by this point major software was already using an industry standard instead -- represented in this library by the SnappyOutputStream and SnappyInputStream methods.

For interoperability with other libraries, check that compatible formats are used. Note that not all libraries support all variants.

Data format compatibility matrix:

Write\ReadSnappy.uncompressSnappyInputStreamSnappyFramedInputStreamorg.apache.hadoop.io.compress.SnappyCodec
Snappy.compressokokxx
SnappyOutputStreamxokxx
SnappyFramedOutputStreamxxokx
SnappyHadoopCompatibleOutputStreamxxxok

BitShuffle API (Since 1.1.3-M2)

BitShuffle is an algorithm that reorders data bits (shuffle) for efficient compression (e.g., a sequence of integers, float values, etc.). To use BitShuffle routines, import org.xerial.snapy.BitShuffle:

import org.xerial.snappy.BitShuffle;

int[] data = new int[] {1, 3, 34, 43, 34};
byte[] shuffledByteArray = BitShuffle.shuffle(data);
byte[] compressed = Snappy.compress(shuffledByteArray);
byte[] uncompressed = Snappy.uncompress(compressed);
int[] result = BitShuffle.unshuffleIntArray(uncompress);

System.out.println(result);

Shuffling and unshuffling of primitive arrays (e.g., short[], long[], float[], double[], etc.) are supported. See Javadoc for the details.

Setting classpath

If you have snappy-java-(VERSION).jar in the current directory, use -classpath option as follows:

$ javac -classpath ".;snappy-java-(VERSION).jar" Sample.java  # in Windows
or
$ javac -classpath ".:snappy-java-(VERSION).jar" Sample.java  # in Mac or Linux

Public discussion group

Post bug reports or feature request to the Issue Tracker: https://github.com/xerial/snappy-java/issues

Public discussion forum is here: Xerial Public Discussion Group

For developers

snappy-java uses sbt (simple build tool for Scala) as a build tool. Here is a simple usage

$ ./sbt            # enter sbt console
> ~test            # run tests upon source code change
> ~testOnly        # run tests that matches a given name pattern  
> publishM2        # publish jar to $HOME/.m2/repository
> package          # create jar file
> findbugs         # Produce findbugs report in target/findbugs
> jacoco:cover     # Report the code coverage of tests to target/jacoco folder

If you need to see detailed debug messages, launch sbt with -Dloglevel=debug option:

$ ./sbt -Dloglevel=debug

For the details of sbt usage, see my blog post: Building Java Projects with sbt

Building from the source code

See the build instruction. Building from the source code is an option when your OS platform and CPU architecture is not supported. To build snappy-java, you need Git, JDK (1.6 or higher), g++ compiler (mingw in Windows) etc.

$ git clone https://github.com/xerial/snappy-java.git
$ cd snappy-java
$ make

When building on Solaris, use gmake:

$ gmake

A file target/snappy-java-$(version).jar is the product additionally containing the native library built for your platform.

Creating a new release

GitHub action [https://github.com/xerial/snappy-java/blob/master/.github/workflows/release.yml] will publish a new relase to Maven Central (Sonatype) when a new tag vX.Y.Z is pushed.

Miscellaneous Notes

Using snappy-java with Tomcat 6 (or higher) Web Server

Simply put the snappy-java's jar to WEB-INF/lib folder of your web application. Usual JNI-library specific problem no longer exists since snappy-java version 1.0.3 or higher can be loaded by multiple class loaders.

Configure snappy-java using property file

Prepare org-xerial-snappy.properties file (under the root path of your library) in Java's property file format. Here is a list of the available properties:

Snappy-java is developed by Taro L. Saito. Twitter @taroleo