One-JAR Quick Start

Quick Start
There are various approaches to getting started with One-JAR. Ant users will find the "Application Generator Approach" most useful, Maven users the "Maven Approach", command-line tool users may prefer the "Command Line Approach".
Application Generator Approach
This approach provides you with a complete Eclipse/Ant application directory, which you can use as a starting point for your own One-JAR application. The application generator is driven by a template built into the one-jar-appgen.jar file (see one-jar-appgen)

    Download one-jar-appgen-0.97.jar
    Generate application, build, and run it.

    $ java -jar one-jar-appgen-0.97.jar

    Enter project path (project name is last segment): c:/tmp/test-one-jar
    Enter java package name: com.example.onejar

    $ cd c:/tmp/test-one-jar
    $ ant
    $ cd build
    $ java -jar test-one-jar.jar

    test_one_jar main entry point, args=[]
    test_one_jar main is running
    test_one_jar OK.

Add source code to the src directory, library jars to the lib directory, and rebuild.
Command-Line Approach
The use of Ant is not required: a One-JAR archive is simple to build using just the jar tool using the following steps.

    Create a working directory to act as the "root" of the one-jar with main, lib sub-directories.
    Copy your main application jar file into root/main and library dependencies into root/lib
    Unjar the one-jar-boot-0.97.jar file into the root directory, and delete the "src" tree
    Edit the boot-manifest.mf file and add a new line: One-Jar-Main-Class: your-main-class
    cd root; jar -cvfm ../one-jar.jar boot-manifest.mf .

You should end up with a One-JAR archive which mirrors the "root" tree:

one-jar.jar
|  META-INF/MANIFEST.MF
|  .version
|  com/simontuffs/onejar
   |  Boot.class, ...etc.
|  doc/one-jar-license.txt
|  main/main.jar
|  lib/a.jar ...etc.

Thats it: no code to write, just a directory tree, some copy operations, and a file edit. The One-JAR classloader discovers the libraries and main code based on their position in the archive, and ignores any other Jar files should you need to embed archives which should not be on the classpath. Embedding the one-jar-license.txt ensures compliance with the BSD-style license.
Maven Approach
There is a Maven2 plugin for One-JAR. It is easy to use for Maven projects. Please consult the documentation here: http://code.google.com/p/onejar-maven-plugin/
Ant Taskdef Approach
Detailed use of the One-JAR Ant Taskdef is discussed here. Note that the one-jar-appgen approach uses the Ant taskdef.
SDK Approach
Use of the (deprecated) SDK is discussed here