JavaFX Proguard Obfuscation

Question

I'm struggling with obfuscation of JavaFX application. Using this project as a base:

https://github.com/openjfx/samples/tree/master/IDE/IntelliJ/Non-Modular/Gradle

Proguard throws this error:

java.io.IOException: Can't write [Path\infile.jar] (Can't read [Path\outfile.jar] (Duplicate jar entry [a.class]))

Proguard config file: -dontoptimize -dontshrink

-libraryjars 'E:\Prog\jdk-11.0.2\jmods'
-libraryjars 'E:\Prog\javafx-sdk\lib'

# Save meta-data for stack traces
-renamesourcefileattribute SourceFile
-keepattributes SourceFile,LineNumberTable

# Rename FXML files together with related views
-adaptresourcefilenames **.fxml,**.png,**.css
-adaptresourcefilecontents **.fxml
-adaptclassstrings

# Keep all annotations and meta-data
-keepattributes *Annotation*,Signature,EnclosingMethod

# Keep entry-point class
-keep classpackage.App {
    public static void main(java.lang.String[]);
}

# Keep all classes inside application
-keep,allowobfuscation class package.** {
}

# Keep names of fields marked with @FXML attribute
-keepclassmembers class * {
    @javafx.fxml.FXML *;
}

Anybody have experience with JavaFX obfuscation?

Answer 1

To get Proguard working with Java 11 we need:

• The latest Proguard beta version, for Gradle in this case.

• Modify the build gradle file to include the proguard task.

• Add a proguard config file including the required changes for Java 11.

Build.gradle

Starting from the HelloFX sample, the build will be modified to:

// 1. Include proguard dependency
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'net.sf.proguard:proguard-gradle:6.1.0beta2'
    }
}

plugins {
  id 'application'
  id 'org.openjfx.javafxplugin' version '0.0.7'
}

repositories {
    mavenCentral()
}

dependencies {
}

javafx {
    modules = [ 'javafx.controls', 'javafx.fxml' ]
}

mainClassName = 'org.openjfx.MainApp'

Instead of just adding the proguard task, I'll add a few more tasks to replace the default build/classes with the proguarded ones. This helps inspecting the result.

// 2. Add tasks

// 2.1 Clean buildDir before running proguard
task cleanClasses(type: Delete) {
    delete "${buildDir}/classes/java/main"
    delete "${buildDir}/resources/java/main"
}

classes.dependsOn(cleanClasses)

// 2.2 Add proguard task
task proguard(type: proguard.gradle.ProGuardTask, dependsOn: classes) {
    injars project.sourceSets.main.output
    outjars "${buildDir}/proguard/output.jar"

    libraryjars project.sourceSets.main.compileClasspath

    configuration 'proguard.conf'
}

// 2.3 Clean after proguard task
task cleanAfterProguard(type: Delete, dependsOn: proguard) {
    delete "${buildDir}/classes/java/main"
    delete "${buildDir}/resources/java/main"
}

// 2.4 Extract output jar to buildDir 
task unpackProguardOutput (type: Copy, dependsOn: cleanAfterProguard) {
    from zipTree("${buildDir}/proguard/output.jar")
    into file("${buildDir}/classes/java/main")
}

Finally, add a task to run the application with the proguarded classes.

// 3. Create a task to run the app with the proguarded buildDir
task runProguard(type: JavaExec, dependsOn: unpackProguardOutput) {
    classpath = sourceSets.main.runtimeClasspath
    jvmArgs = ['--module-path', classpath.asPath,
               '--add-modules', 'javafx.controls,javafx.fxml' ]
    main = 'a.a.b' // <-- this name will depend on the proguard result
}

proguard.conf

The key on how to get it working with Java 9+ can be found in this comment. If you download the source code, and check the examples folder, there are different configuration files.

Checking applications.pro, you can read:

# Before Java 9, the runtime classes were packaged in a single jar file.
#-libraryjars <java.home>/lib/rt.jar

# As of Java 9, the runtime classes are packaged in modular jmod files.
-libraryjars <java.home>/jmods/java.base.jmod(!**.jar;!module-info.class)

So that's it!

This is the config file I've used with the HelloFX sample (of course it could be extended with other many options):

-dontoptimize
-dontshrink

#Java 9+
-libraryjars <java.home>/jmods/java.base.jmod(!**.jar;!module-info.class)

# Save meta-data for stack traces
-printmapping out.map
-renamesourcefileattribute SourceFile
-keepattributes SourceFile,LineNumberTable

# Rename FXML files together with related views
-adaptresourcefilenames **.fxml,**.png,**.css,**.properties
-adaptresourcefilecontents **.fxml
-adaptclassstrings

# Keep all annotations and meta-data
-keepattributes *Annotation*,Signature,EnclosingMethod

# Keep entry-point class
-keep class org.openfjx.MainApp {
  public static void main(java.lang.String[]);
}

# Keep names of fields marked with @FXML, @Inject and @PostConstruct attributes
-keepclassmembers class * {
  @javafx.fxml.FXML *;
  @javax.inject.Inject *;
  @javax.annotation.PostConstruct *;
}

Result

If you run ./gradlew proguard, you will get the output.jar.

If you run ./gradlew unpackProguardOutput, you can see the result in build/classes:

main
|____a
| |____a
| | |____styles.css
| | |____scene.fxml
| | |____b.class
| | |____a.class

In this case, b.class is the main class, so this is why in the runProguard task I've set main = 'a.a.b'. This will depend on each case, obviously.

Also, you can check the out.map:

org.openjfx.FXMLController -> a.a.a:
    javafx.scene.control.Label label -> label
    10:10:void <init>() -> <init>
    17:20:void initialize(java.net.URL,java.util.ResourceBundle) -> initialize
org.openjfx.MainApp -> a.a.b:
    11:11:void <init>() -> <init>
    15:23:void start(javafx.stage.Stage) -> start
    26:27:void main(java.lang.String[]) -> a

Finally, ./gradlew runProguard will successfully run the application.