Packages your JAR, assets and a JVM for distribution on Windows, Linux and Mac OS X, adding a native executable file to make it appear like the app is a native app. Packr is most suitable for GUI applications, such as games made with libGDX.

You point packr at your JAR file (containing all your code and assets), a JSON config file (specifying parameters to the JVM and the main class) and a URL or local file location to an OpenJDK build for the platform you want to build. Invoking packr from the command line may look like this:

java -jar packr.jar \
     -platform mac \
     -jdk "openjdk-1.7.0-u45-unofficial-icedtea-2.4.3-macosx-x86_64-image.zip" \
     -executable myapp \
     -classpath myapp.jar \
     -mainclass "com.my.app.MainClass" \
     -vmargs "-Xmx1G" \
     -resources src/main/resources;path/to/other/assets \
     -minimizejre "soft" \
     -outdir out

Alternatively, you can put all the command line arguments into a JSON file which might look like this:

{
    "platform": "mac",
    "jdk": "/Users/badlogic/Downloads/openjdk-1.7.0-u45-unofficial-icedtea-2.4.3-macosx-x86_64-image.zip",
    "executable": "myapp",
    "classpath": [
        "myapp.jar"
    ],
    "mainclass": "com.my.app.MainClass",
    "vmargs": [
       "-Xmx1G"
    ],
    "resources": [
        "src/main/resources",
        "path/to/other/assets"
    ],
    "minimizejre": "soft",
    "outdir": "out-mac"
}

You can then invoke the tool like this:

java -jar packr.jar my-packr-config.json

Finally, you can use packr from within your code. Just add the JAR file to your project, either manually, or via the following Maven dependency:

<dependency>
   <groupId>com.badlogicgames.packr</groupId>
   <artifactId>packr</artifactId>
   <version>2.0</version>
</dependency>

To invoke packr, you need to create an instance of Config and pass it to Packr.pack()

Config config = new Config();
config.platform = Platform.windows;
config.jdk = "/User/badlogic/Downloads/openjdk-for-mac.zip";
config.executable = "myapp";
config.classpath = Arrays.asList("myjar.jar");
config.mainClass = "com.my.app.MainClass";
config.vmArgs = Arrays.asList("-Xmx1G");
config.minimizeJre = new String[] { "jre/lib/rt/com/sun/corba", "jre/lib/rt/com/sun/jndi" };
config.outDir = "out-mac";

new Packr().pack(config)

A standard JRE weighs about 90mb unpacked and about 50mb packed. Packr helps you cut down on that size, thus also reducing the download size of your app.

To minimize the JRE that is bundled with your app, you have to specify a minimization configuration file via the minimizejre flag you supply to Packr. Such a minimization configuration contains the names of files and directories within the JRE to be removed, one per line in the file. E.g.:

jre/lib/rhino.jar
jre/lib/rt/com/sun/corba

This will remove the rhino.jar (about 1.1MB) and all the packages and classes in com.sun.corba from the rt.jar file. To specify files and packages to be removed from the JRE, simply prepend them with jre/lib/rt/.

Packr comes with two such configurations out of the box, soft and hard

Additionally, Packr will compress the rt.jar file. By default, the JRE uses zero-compression on the rt.jar file to make application startup a little faster.

When packing for Windows, the following folder structure will be generated

outdir/
   executable.exe
   yourjar.jar
   config.json
   jre/

Linux

outdir/
   executable
   yourjar.jar
   config.json
   jre/

Mac OS X

outdir/
   Contents/
      Info.plist
      MacOS/
         executable
         yourjar.jar
         config.json
         jre/
      Resources/
         icons.icns [if config.icon is set]

You can further modify the Info.plist to your liking, e.g. add icons, a bundle identifier etc. If your outdir has the .app extension it will be treated as an application bundle by Mac OS X.

By default, the native executables forward any command line parameters to your Java application's main() function. So, with the configurations above, ./myapp -x y.z is passed as com.my.app.MainClass.main(new String[] {"-x", "y.z" }).

The executables themselves expose an own interface, which has to be explicitly enabled by passing -c or --cli as the very first parameter. In this case, a special delimiter parameter -- is used to separate the native CLI from parameters to be passed to Java. In this case, the example above would be equal to ./myapp -c [arguments] -- -x y.z.

Try ./myapp -c --help for a list of available options. They are also listed here.

Note: On Windows, the executable does not show any output by default. Here you can use myapp.exe -c --console --help to spawn a console window, making terminal output visible.

If you want to modify the Java code only, it's sufficient to invoke Maven.

mvn clean package

This will create a packr-VERSION.jar file in target which you can invoke as described in the Usage section above.

If you want to compile the native executables, please follow these instructions. Each of the build scripts will create executable files for the specific platform and copy them to src/main/resources.

• Icons aren't set yet on Windows and Linux, you need to do that manually.
• Minimum platform requirement on MacOS is OS X 10.7.
• JRE minimization is very conservative. Depending on your app, you can carve out stuff from a JRE yourself, disable minimization and pass your custom JRE to packr.
• On MacOS, the JVM is spawned in its own thread by default, which is a requirement of AWT. This does not work with code based on LWJGL3/GLFW, which needs the JVM be spawned on the main thread. You can enforce the latter with the -XstartOnFirstThread VM argument in your packr config.

The code is licensed under the Apache 2 license. By contributing to this repository, you automatically agree that your contribution can be distributed under the Apache 2 license by the author of this project. You will not be able to revoke this right once your contribution has been merged into this repository.

Distributing a bundled JVM has security implications, just like bundling any other runtimes like Mono, Air, etc. Make sure you understand the implications before deciding to use this tool. Here's a discussion on the topic.