Proguard-Get-Started

Overview

This document explains how to use Proguard in your application. ProGuard is an open source command-line tool that shrinks, optimizes and obfuscates Java code. It is able to optimize bytecode as well as detect and remove unused instructions. For example, Proguard can be used to remove all log message in binary production. This project is based on Proguard version 5.1.

Requirements

This how-to has been tested on:

• MicroEJ SDK 5.1

Usage

ADD THE DEPENDENCIES

1. Open the module.ivy.

2. Copy the following code inside <ea:build organisation=...></ea:build> :

   <ea:plugin organisation="com.is2t.easyant.plugins" module="obf-proguard" revision="+"/>
   

ADD PROGUARD RULES

1. File → New → File

   • File name : module.pro → you must create a file with this name.

2. Copy the following code inside this file :

   -assumenosideeffects class java.util.logging.Logger {
   public static java.util.logging.Logger getLogger(...);
   public static Logger getLogger(...);
   public void log(...);
   public void severe(...);
   public void config(...);
   public void fine(...);
   public void finer(...);
   public void finest(...);
   public void info(...);
   public void warning(...);
   }
   

An example file is available @module.pro.

BUILD EASYANT

1. Click on Build selected EasyAnt projects.

2. Verify Proguard is called during the build. Open EasyAnt Console and search for the following lines :

   obf-proguard:obfuscate:
      [move] Moving 1 file to C:\Users\mmartins\Documents\Work\SupportWorkspace\a\target~\build-env
      [copy] Copying 1 file to C:\Users\mmartins\Documents\Work\SupportWorkspace\a\target~\proguard
   [proguard] ProGuard, version 5.1
   

CHECKING

Bytecode is compared. You can find the .jar of your application in the folder target~/artifacts.

Example Java

public Main() {
   System.out.println("1");
   LOGGER.severe("severe call");
   System.out.println("2");
   LOGGER.config("config call");
   System.out.println("3");
}

Bytecode generated

• We can see than severe(…) and config(…) methods are called (L.25 & L.42).

  14  ldc <String "1"> [1]
  16  invokevirtual java.io.PrintStream.println(java.lang.String) : void [17]
  19  aload_1
  20  getfield com.mycompany.aA.a : java.util.logging.Logger [15]
  23  ldc <String "severe call"> [6]
  25  invokevirtual java.util.logging.Logger.severe(java.lang.String): void [23]
  28  getstatic java.lang.System.out : java.io.PrintStream [16]
  31  ldc <String "2"> [2]
  33  invokevirtual java.io.PrintStream.println(java.lang.String) : void [17]
  36  aload_1
  37  getfield com.mycompany.aA.a : java.util.logging.Logger [15]
  40  ldc <String "config cal"> [7]
  42  invokevirtual java.util.logging.Logger.config(java.lang.String) : void [23]
  45  getstatic java.lang.System.out : java.io.PrintStream [16]
  48  ldc <String "3"> [3]
  

Proguard

• After Proguard processing, we can see than severe(…) and config(…) are removed.

  5  ldc <String "1"> [1]
  7  invokevirtual java.io.PrintStream.println(java.lang.String) : void [13]
  10  getstatic java.lang.System.out : java.io.PrintStream [12]
  13  ldc <String "2"> [2]
  15  invokevirtual java.io.PrintStream.println(java.lang.String) : void [13]
  18  getstatic java.lang.System.out : java.io.PrintStream [12]
  21  ldc <String "3"> [3]
  23  invokevirtual java.io.PrintStream.println(java.lang.String) : void [13]
  

• Java code

  public Main() {
     System.out.println(“1”);
     System.out.println(“2”);
     System.out.println(“3”);
  }