packr
Public Service Announcement: With packr v2.0, command line interfaces to both packr.jar and the native executable have changed, as well as the format of minimize profiles! If you upgrade from a previous version, please read this documentation again to make sure you've updated your configuration(s) accordingly.
About
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 a native app. Packr is most suitable for GUI applications, such as games made with libGDX.
Download
The latest build is available for download here.
Usage
You point packr at your JAR file(s) containing your code and assets, some configuration parameters, and a URL or local file location to a JDK build for your target platform.
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 \
--removelibs myapp.jar \
--mainclass com.my.app.MainClass \
--vmargs Xmx1G \
--resources src/main/resources path/to/other/assets \
--minimizejre soft \
--output out-mac
Parameter | Meaning |
---|---|
platform | one of "windows32", "windows64", "linux32", "linux64", "mac" |
jdk | directory, ZIP file, or URL to ZIP file of an OpenJDK or Oracle JDK build containing a JRE. Prebuild OpenJDK packages can be found at https://github.com/alexkasko/openjdk-unofficial-builds. You can also specify a directory to an unpacked JDK distribution. E.g. using ${java.home} in a build script |
executable | name of the native executable, without extension such as ".exe" |
classpath | file locations of the JAR files to package |
removelibs (optional) | file locations of JAR files to remove native libraries which do not match the target platform. See below for details. |
mainclass | the fully qualified name of the main class, using dots to delimit package names |
vmargs | list of arguments for the JVM, without leading dashes, e.g. "Xmx1G" |
resources (optional) | list of files and directories to be packaged next to the native executable |
minimizejre | minimize the JRE by removing directories and files as specified by an additional config file. Comes with a few config files out of the box. See below for details on the minimization config file. |
output | the output directory |
cachejre (optional) | An optional directory to cache the result of JRE extraction and minimization. See below for details. |
icon (optional, OS X) | location of an AppBundle icon resource (.icns file) |
bundle (optional, OS X) | the bundle identifier of your Java application, e.g. "com.my.app" |
verbose | prints more status information during processing, which can be useful for debugging |
help | shows the command line interface help |
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"
],
"removelibs": [
"myapp.jar"
],
"mainclass": "com.my.app.MainClass",
"vmargs": [
"Xmx1G"
],
"resources": [
"src/main/resources",
"path/to/other/assets"
],
"minimizejre": "soft",
"output": "out-mac"
}
You can then invoke the tool like this:
java -jar packr.jar my-packr-config.json
It is possible to combine a JSON configuration and the command line. For single options, the command line parameter overrides the equivalent JSON option. For multi-options (e.g. classpath
or vmargs
), the options are merged.
This is an example which overrides the output folder and adds another VM argument. Note that the config file name is delimited by --
because the option prior to it, --vmargs
, allows multiple arguments:
java -jar packr.jar --output target/out-mac --vmargs Xms256m -- my-packr-config.json
Finally, you can use packr from within your Java code. Just add the JAR file to your project, either manually, or via the following Maven dependency:
<repositories>
<repository>
<url>https://oss.sonatype.org/content/repositories/snapshots</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
</repositories>
<dependency>
<groupId>com.badlogicgames.packr</groupId>
<artifactId>packr</artifactId>
<version>2.1</version>
</dependency>
To invoke packr, you need to create an instance of PackrConfig
and pass it to Packr.pack()
:
PackrConfig config = new PackrConfig();
config.platform = PackrConfig.Platform.Windows32;
config.jdk = "/User/badlogic/Downloads/openjdk-for-mac.zip";
config.executable = "myapp";
config.classpath = Arrays.asList("myjar.jar");
config.removePlatformLibs = config.classpath;
config.mainClass = "com.my.app.MainClass";
config.vmArgs = Arrays.asList("Xmx1G");
config.minimizeJre = "soft";
config.outDir = new java.io.File("out-mac");
new Packr().pack(config);
Minimization
JRE
A standard OpenJDK JRE weighs about 90 mb unpacked. 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. A minimization configuration is a JSON file containing paths to files and directories within the JRE to be removed.
As an example, have a look at the soft
profile configuration:
{
"reduce": [
{
"archive": "jre/lib/rt.jar",
"paths": [
"com/sun/corba",
"com/sun/jndi",
"com/sun/media",
"com/sun/naming",
"com/sun/rowset",
"sun/applet",
"sun/corba",
"sun/management"
]
}
],
"remove": [
{
"platform": "*",
"paths": [
"jre/lib/rhino.jar"
]
},
{
"platform": "windows",
"paths": [
"jre/bin/*.exe",
"jre/bin/client"
]
}
]
}
This configuration will unpack rt.jar
, remove all the listed packages and classes in com.sun.*
and sun.*
, then repack rt.jar
again. By default, the JRE uses zero-compression on its JAR files to make application startup a little faster, so this step will reduce the size of rt.jar
substantially.
Then, rhino.jar (about 1.1MB) and, in case of a Windows JRE, all executable files in jre/bin/
and the folder jre/bin/client/
will be removed.
Packr comes with two such configurations out of the box, soft
and hard
. The hard
profile removes a few more files, and repacks some additional JAR files.
There's also a new, experimental configuration, oraclejre8
, which reduces size of an Oracle 8 JRE following Oracle's redistribution rules described here. It also repacks JAR files, reducing (unpacked) JRE size from about 180 mb to 70 mb. This version is pretty much untested, so please use with care!
The "removelibs" option
Minimization aside, packr can remove all dynamic libraries which do not match the target platform from your project JAR file(s):
platform | files removed |
---|---|
Windows | *.dylib , *.so |
Linux | *.dll , *.dylib |
MacOS | *.dll , *.so |
This step is optional. If you don't need it, just remove the configuration parameter to speed up packr.
Caching
Extracting and minimizing a JRE can take quite some time. If the cachejre
option is used, the result of these operations is cached in the given folder, and can be reused in subsequent runs of packr.
As of now, packr doesn't do any elaborate checks to validate the content of this cache folder. So if you update the JDK, or change the minimize profile, you need to empty or remove this folder manually to force a change.
Output
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
Resources/
yourjar.jar
config.json
jre/
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 output
folder has the .app
extension it will be treated as an application bundle by Mac OS X.
Executable command line interface
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 enabled explicitly by passing -c
or --cli
as the very first parameter. In this case, the 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 [arguments]
to spawn a console window, making terminal output visible.
Building from source code
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.
Limitations
- 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 adding the
-XstartOnFirstThread
VM argument to your MacOS packr config.
License & Contributions
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.
Security
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.