diff --git a/lib/closure/compiler.rb b/lib/closure/compiler.rb
index 111e40d..1770e7b 100644
--- a/lib/closure/compiler.rb
+++ b/lib/closure/compiler.rb
@@ -9,43 +9,89 @@ class Error < StandardError; end
   # The Closure::Compiler is a basic wrapper around the actual JAR. There's not
   # much to see here.
   class Compiler
-    
+
     DEFAULT_OPTIONS = {:warning_level => 'QUIET'}
 
     # When you create a Compiler, pass in the flags and options.
     def initialize(options={})
-      @java     = options.delete(:java)     || JAVA_COMMAND
-      @jar      = options.delete(:jar_file) || COMPILER_JAR
-      @options  = serialize_options(DEFAULT_OPTIONS.merge(options))
+
+      # load closure.jar in same jruby jvm
+      if defined?(JRUBY_VERSION)
+        jar_path = File.expand_path "../closure-compiler-20111003.jar", File.dirname(__FILE__)
+        require jar_path
+        @options = DEFAULT_OPTIONS.merge(options)
+      else
+        @java     = options.delete(:java)     || JAVA_COMMAND
+        @jar      = options.delete(:jar_file) || COMPILER_JAR
+        @options  = serialize_options(DEFAULT_OPTIONS.merge(options))
+      end
     end
 
     # Can compile a JavaScript string or open IO object. Returns the compiled
     # JavaScript as a string or yields an IO object containing the response to a
     # block, for streaming.
     def compile(io)
-      tempfile = Tempfile.new('closure_compiler')
-      if io.respond_to? :read
-        while buffer = io.read(4096) do
-          tempfile.write(buffer)
-        end
+
+      # don't fork a java process.
+      if defined?(JRUBY_VERSION)
+        
+        # load java classes.
+        require 'java'
+        import com.google.javascript.jscomp.JSSourceFile
+        import com.google.javascript.jscomp.Compiler
+        import com.google.javascript.jscomp.VariableRenamingPolicy
+        import com.google.javascript.jscomp.CompilerOptions
+        import com.google.javascript.jscomp.CompilationLevel
+        import com.google.javascript.jscomp.WarningLevel
+
+        import java.util.logging.Level
+        com.google.javascript.jscomp.Compiler.setLoggingLevel(Level::WARNING)
+
+        compiler =  com.google.javascript.jscomp.Compiler.new()
+        opts = CompilerOptions.new
+
+        # simple settings
+        compilation_level = @options[:compilation_level] || 'SIMPLE_OPTIMIZATIONS'
+        warning_level = @options[:warning_level]
+
+        CompilationLevel.const_get(compilation_level).setOptionsForCompilationLevel(opts)
+        WarningLevel.const_get(warning_level).setOptionsForWarningLevel(opts)
+
+        # TODO: add js name.
+        source = JSSourceFile.fromCode("unknown", io)
+
+        res = compiler.compile([], [source], opts)
+        result = compiler.toSource() + "\n"
+
+        raise Error, result unless res.success
+
+        yield(StringIO.new(result)) if block_given?
+        return result
       else
-        tempfile.write(io.to_s)
-      end
-      tempfile.flush
-
-      begin
-        result = `#{command} --js #{tempfile.path} 2>&1`
-      rescue Exception
-        raise Error, "compression failed: #{result}"
-      ensure
-        tempfile.close!
-      end
-      unless $?.exitstatus.zero?
-        raise Error, result
-      end
+        tempfile = Tempfile.new('closure_compiler')
+        if io.respond_to? :read
+          while buffer = io.read(4096) do
+            tempfile.write(buffer)
+          end
+        else
+          tempfile.write(io.to_s)
+        end
+        tempfile.flush
 
-      yield(StringIO.new(result)) if block_given?
-      result
+        begin
+          result = `#{command} --js #{tempfile.path} 2>&1`
+        rescue Exception
+          raise Error, "compression failed: #{result}"
+        ensure
+          tempfile.close!
+        end
+        unless $?.exitstatus.zero?
+          raise Error, result
+        end
+
+        yield(StringIO.new(result)) if block_given?
+        result
+      end
     end
     alias_method :compress, :compile