Using jlink to deploy native(*) Java applications

A demo of using Java 9 modularization, and the JDK's new jlink tool, for zero-dependency deployments. That is, application bundles suitable for native(*) execution, with the Java runtime embedded.

Unlike older approaches, which required embedding basically an entire JRE (around 200+ megs), the jlink tool allows you to strip down the embedded runtime to include only those portions of the standard library that are absolutely necessary.

(*) No, this is not "native" in the C/C++ sense of AOT compilation. There is still a Java Runtime Environment executing the code. However, the code is packaged up into a deployable bundle, with a JRE and launch script native to the specific target platform (i.e. UNIX shell or Windows batch). No other software needs to be installed, and the end user experience is no different from an application shipping with Qt or GTK shared libs.

Results

This repository contains a Gradle multi-project setup, with two sub-projects. One is a basic "Hello World" command-line application, and the other a JavaFX app. These are the resulting sizes of the native application bundles that are generated, both raw as well as after being compressed with 7-zip, on a 64-bit Windows system (with Electron for comparison):

App	Compressed with 7-zip	Raw Size when deployed
cli (command-line application)	10.8 MB	21.7 MB
gui (JavaFX desktop application)	29.1 MB	45.8 MB
electron-quick-start example	32.8 MB	131 MB

How to Build

To run these Gradle commands, your system must have a JAVA_HOME environment variable pointing to a Java 9+ location (the JDK subdirectory, not the JRE one).

gradlew linkAll

To build the command-line version or the JavaFX version separately, use:

gradlew cli:link

gradlew gui:link

You can find the output under the cli/build/dist and/or gui/build/dist subdirectories.

Each bundle will have a /bin subdirectory, containing UNIX shell scripts or Windows batch files with the same name as the subproject (e.g. cli, gui.bat).

The contents of either dist subdirectory can be copied and run anywhere (assuming the same platform type as the machine on which the bundle was made). You could also use any installer tool of your choice to make a one-click installer artifact.