1. Taro L. Saito
  2. snappy-java

Overview

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This document is a copy of http://code.google.com/p/snappy-java/

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The snappy-java is a Java port of the snappy http://code.google.com/p/snappy/, a fast compresser/decompresser written in C++ developed by Google.

== Features ==
  * [http://www.apache.org/licenses/LICENSE-2.0 Apache Licence Version 2.0]. Free for both commercial and non-commercial use.
  * Fast compression/decompression tailored to 64-bit CPU architecture. 
  * JNI-based implementation to achieve comparable performance to the native C++ version.  
     * Although snappy-java uses JNI, it can be used safely with multiple class loaders (e.g. Tomcat, etc.). 
  * Portable across various operating systems; Snappy-java contains native libraries built for Window/Mac/Linux (32/64-bit). At runtime, snappy-java loads one of these libraries according to your machine environment (It looks system properties, `os.name` and `os.arch`). 
  * Simple usage. Add the snappy-java-(version).jar file to your classpath. Then call compression/decompression methods in org.xerial.snappy.Snappy. 

== Performance ==
  * Snappy's main target is very high-speed compression/decompression with reasonable compression size. So the compression ratio of snappy-java is modest and about the same as `LZF` (ranging 20%-100% according to the dataset).

  * Here are some [https://github.com/ning/jvm-compressor-benchmark/wiki benchmark results], comparing snappy-java and the other compressors `LZO-java`/`LZF`/`QuickLZ`/`Gzip`/`Bzip2`. Thanks [http://twitter.com/#!/cowtowncoder Tatu Saloranta @cowtowncoder] for providing the benchmark suite. 
 * The benchmark result indicates snappy-java is the fastest compreesor/decompressor in Java:
    * http://ning.github.com/jvm-compressor-benchmark/results/canterbury-roundtrip-2011-07-28/index.html
 * The decompression speed is twice as fast as the others:
    * http://ning.github.com/jvm-compressor-benchmark/results/canterbury-uncompress-2011-07-28/index.html



== Download ==
The current stable version 1.0.3.1 is available from here:
  * Release version: http://maven.xerial.org/repository/artifact/org/xerial/snappy/snappy-java
    * [Milestone] release plans
  * Snapshot version (the latest beta version): http://maven.xerial.org/repository/snapshot/org/xerial/snappy/snappy-java/

If you are a Maven user, see [#Using_with_Maven]

== 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. See also 
[http://code.google.com/p/snappy-java/source/browse/src/main/java/org/xerial/snappy/Snappy.java Snappy.java]

===Stream-based API===
Stream-based compressor/decompressor `SnappyOutputStream`/`SnappyInputStream` are also available for reading/writing large data sets.

===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
}}}

===Using with Maven===
  * Snappy-java is available from Maven's central repository:  http://repo1.maven.org/maven2/org/xerial/snappy/snappy-java 

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>
}}}

==Public discussion group==
Post bug reports or feature request to the Issue Tracker: http://code.google.com/p/snappy-java/issues/list

Public discussion forum is here: [http://groups.google.com/group/xerial?hl=en Xerial Public Discussion Group]. 


== Building from the source code ==
See the [http://code.google.com/p/snappy-java/source/browse/INSTALL installation 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 Mercurial(hg), JDK (1.6 or higher), Maven (3.x or higher is required), g++ compiler (mingw in Windows) etc.

{{{
$ hg clone https://snappy-java.googlecode.com/hg/ snappy-java 
$ cd snappy-java
$ make
}}}

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

==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 in the same JVM by using native code injection to the parent class loader (Issue 21). 


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Snappy-java is developed by [http://www.xerial.org/leo Taro L. Saito]. Twitter  [http://twitter.com/#!/taroleo @taroleo]