/*

  * Copyright 2005-2007 The Kuali Foundation

  *

  *

  * Licensed under the Educational Community License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  *

  * http://www.opensource.org/licenses/ecl2.php

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package org.kuali.rice.core.proxy;

 import java.lang.reflect.InvocationHandler;

 import java.lang.reflect.Method;

 import org.kuali.rice.core.util.ExceptionUtils;

 /**

  * An abstract base class for InvocationHanlders which can be used to implement

  * an InvocationHandler that delegates hashCode and equals methods to the proxied

  *

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public abstract class BaseInvocationHandler implements InvocationHandler {

         // preloaded Method objects for the methods in java.lang.Object

     private static Method hashCodeMethod;

     private static Method equalsMethod;

     static {

         try {

             hashCodeMethod = Object.class.getMethod("hashCode", (Class[])null);

             equalsMethod = Object.class.getMethod("equals", new Class[] { Object.class });

             } catch (NoSuchMethodException e) {

                     throw new NoSuchMethodError(e.getMessage());

             }

     }

         public Object invoke(Object proxy, Method method, Object[] arguments) throws Throwable {

                 Class declaringClass = method.getDeclaringClass();

                 if (declaringClass == Object.class) {

                     if (method.equals(hashCodeMethod)) {

                             return proxyHashCode(proxy);

                     } else if (method.equals(equalsMethod)) {

                             return proxyEquals(proxy, arguments[0]);

                     } /*else if (m.equals(toStringMethod)) {

                         return proxyToString(proxy);

                     } else {

                         throw new InternalError(

                             "unexpected Object method dispatched: " + m);

                     }*/

                 }

                 try {

                         return invokeInternal(proxy, method, arguments);

                 } catch (Throwable t) {

                         throw ExceptionUtils.unwrapActualCause(t);

                 }

         }

         protected abstract Object invokeInternal(Object proxy, Method method, Object[] arguments) throws Throwable;

         protected Integer proxyHashCode(Object proxy) {

                 return new Integer(System.identityHashCode(proxy));

         }

         protected Boolean proxyEquals(Object proxy, Object other) {

                 return (proxy == other ? Boolean.TRUE : Boolean.FALSE);

         }

 }