Decompile APK

1. Change .APK to .ZIP and unzip it. There is classes.dex in the folder.
2. Download dex2jar(http://code.google.com/p/dex2jar/) to convert classes.dex to classes.
     . dex2jar.sh PATH_TO_CLASSES_DEX/classes.dex
    
    The command should generate classes_dex2jar.jar
3. Download jdgui(http://mac.softpedia.com/dyn-postdownload.php?p=48710&t=4&i=1) to unzip jar file.
    Open jdgui and choose classes_dex2.jar.jar.  All folder and java file should be browsed in JDGUI.  
    Save all source.

4. Download android-apktool(https://code.google.com/p/android-apktool/downloads/list). Choose "apktool1.5.2.tar.bz2" and "apktool-install-macosx-r05-ibot.tar.bz2"(This depends on platform).
    . apktool d PATH_TO_APK/xxx.apk
   All resource and xml file are generated in APK_NAME folder