import java.lang.reflect.*;

/**
 * QuarkTrace is a dynamic proxy that adds method call tracing to anything that
 * looks like a Quark (implements IQuark).
 *
 * @author Thornton Rose
 */
public class QuarkTrace implements InvocationHandler {
   private Object realQuark;

   // QuarkTrace(Object):
   /**
    * Create a new QuarkTrace for the given object.
    */
   public QuarkTrace(Object aQuark) {
      realQuark = aQuark;
   }

   // InvocationHandler -------------------------------------------------------

   // invoke(Object, Method, Object[]):
   /**
    * Print <code>method</code> name, then invoke <code>method</code> on 
    * instance of Quark that is being traced.
    */
   public Object invoke(Object proxy, Method method, Object[] args)
         throws Throwable {
      System.out.println("[" + method.getName() + "()]");
      return method.invoke(realQuark, args);
   }
   
   // main --------------------------------------------------------------------
   
   public static void main(String[] args) {
      Class  quarkClass;
      IQuark quark;

      try {
         // Load class.
         
         quarkClass = Class.forName(args[0]);
         
         // Create proxy object.
         
         quark = (IQuark) Proxy.newProxyInstance(
            quarkClass.getClassLoader(),
            new Class[] { IQuark.class },
            new QuarkTrace(quarkClass.newInstance()) );
            
         // Call some methods.
         
         quark.setFlavor("bubblegum");
         System.out.println("flavor = " + quark.getFlavor());
         quark.spin();
      } catch(Throwable t) {
         System.out.println(t);
      }
   }
}