nishtahir/fern

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Step 1. Add the JitPack repository to your build file

Add it in your root settings.gradle at the end of repositories:

	dependencyResolutionManagement {
		repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
		repositories {
			mavenCentral()
			maven { url 'https://jitpack.io' }
		}
	}

Add it in your settings.gradle.kts at the end of repositories:

	dependencyResolutionManagement {
		repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
		repositories {
			mavenCentral()
			maven { url = uri("https://jitpack.io") }
		}
	}

Add to pom.xml

	<repositories>
		<repository>
		    <id>jitpack.io</id>
		    <url>https://jitpack.io</url>
		</repository>
	</repositories>

Add it in your build.sbt at the end of resolvers:

 
    resolvers += "jitpack" at "https://jitpack.io"

Add it in your project.clj at the end of repositories:

 
    :repositories [["jitpack" "https://jitpack.io"]]

Step 2. Add the dependency

	dependencies {
		implementation 'com.github.nishtahir:fern:0.3.2'
	}

	dependencies {
		implementation("com.github.nishtahir:fern:0.3.2")
	}

	<dependency>
	    <groupId>com.github.nishtahir</groupId>
	    <artifactId>fern</artifactId>
	    <version>0.3.2</version>
	</dependency>


                            
    libraryDependencies += "com.github.nishtahir" % "fern" % "0.3.2"


                            
    :dependencies [[com.github.nishtahir/fern "0.3.2"]]

Readme

Fern - FernFlower Gradle plugin

This is a wrapper around the Jetbrains FernFlower decompiler.

Usage

buildscript {

    repositories {
        maven { url "https://jitpack.io" }
        mavenCentral()
    }

    dependencies {
	    classpath 'com.github.nishtahir:fern:0.3.1'

	    // or place the jar in <project-root/libs> folder
	    classpath 'libs/fern-0.3.1'
    }
}

apply plugin: "com.nishtahir.fern"

// or for Android projects
apply plugin: "com.nishtahir.fern-android"

Customization options are exposed via fern extension.


fern {
     classesDir = "" // Directory to scan for class files
     outputDir = ""  // output directory
     enabled = true  // false disables the decompiler - useful in android projects

     removeBridge = true
     removeSynthetic = false
     decompileInner = true
     decompileClass14 = true
     decompileAssertions = true
     hideEmptySuper = true
     hideDefaultConstructor = true
     decompileGenericSignatures = false
     noExceptionsReturn = true
     decompileEnum = true
     removeGetClassNew = true
     literalsAsIs = false
     booleanTrueOne = true
     asciiStringCharacters = false
     syntheticNotSet = true
     undefinedParamTypeObject = true
     useDebugNames = true
     removeEmptyRanges = true
     finallyDeinline = true
     ideaNotNullAnnotation = true
     lambdaToAnonymousClass = false
     bytecodeSourceMapping = false
     logLevel = "info"
     maxProcessingMethod = false
     renameEntities = false
     userRenamerClass = false
     newLineSeparator = false
     indentString = "    "
     banner = ""
     dumpOriginalLines = false
     unitTestMode = false

}

A description on what these options do and how they work can be found in the official FernFlower documentation.

While sensible defaults have been set for Java and Kotlin project class files, you may chose to specify your own sources using the classesDir property in the fern configuration.

fern {
    classesDir = "my/classes/root"
}

By default the decompiler outputs to $buildDir/decompiled-sources/ however you can specify your own output path using the outputDir property.

fern {
    outputDir = "my/output/root"
}

To run the decompiler, simply use the decompile task

./gradlew decompile

If you are decompiling after compiling source, you should run your build step first

./gradlew build decompile

Android projects

For Android projects decompilation works by registering a transform step via the transform api, however decompiling during every build phase can slow down development for this reason, fern exposes an enabled setting allow you to skip the decompilation step.

fern {
    enabled = false
}

Sample

buildscript {
    ext.kotlin_version = "1.2.30"

    repositories {
        maven { url "https://jitpack.io" }
        mavenCentral()
    }
    dependencies {
	    classpath 'com.github.nishtahir:fern:-SNAPSHOT'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

apply plugin: "kotlin"
apply plugin: "com.nishtahir.fern"

fern {
    logLevel = "warn"
}

repositories {
    mavenCentral()
}

dependencies {
    compile "org.jetbrains.kotlin:kotlin-stdlib-jre8:$kotlin_version"
}