def generate(env):
    """Add Builders and construction variables for jar to an Environment."""
    SCons.Tool.CreateJarBuilder(env)

    SCons.Tool.CreateJavaFileBuilder(env)
    SCons.Tool.CreateJavaClassFileBuilder(env)
    SCons.Tool.CreateJavaClassDirBuilder(env)

    env.AddMethod(Jar)

    env['JAR']        = 'jar'
    env['JARFLAGS']   = SCons.Util.CLVar('cf')
    env['_JARFLAGS']  = jarFlags
    env['_JARMANIFEST'] = jarManifest
    env['_JARSOURCES'] = jarSources
    env['_JARCOM']    = '$JAR $_JARFLAGS $TARGET $_JARMANIFEST $_JARSOURCES'
    env['JARCOM']     = "${TEMPFILE('$_JARCOM','$JARCOMSTR')}"
    env['JARSUFFIX']  = '.jar'
Add Builders and construction variables for jar to an Environment.