WrapperBase.java

/*
 Copyright  2002-2004 MySQL AB, 2008 Sun Microsystems
 All rights reserved. Use is subject to license terms.

  The MySQL Connector/J is licensed under the terms of the GPL,
  like most MySQL Connectors. There are special exceptions to the
  terms and conditions of the GPL as it is applied to this software,
  see the FLOSS License Exception available on mysql.com.

  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; version 2 of the
  License.

  This program is distributed in the hope that it will be useful,  
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  02110-1301 USA


 
 */
package com.mysql.jdbc.jdbc2.optional;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.SQLException;
import java.util.Map;

import com.mysql.jdbc.ExceptionInterceptor;
import com.mysql.jdbc.SQLError;

/**
 * Base class for all wrapped instances created by LogicalHandle
 * 
 * @author Mark matthews
 * 
 * @version $Id$
 */
abstract class WrapperBase {
	protected MysqlPooledConnection pooledConnection;

	/**
	 * Fires connection error event if required, before re-throwing exception
	 * 
	 * @param sqlEx
	 *            the SQLException that has ocurred
	 * @throws SQLException
	 *             (rethrown)
	 */
	protected void checkAndFireConnectionError(SQLException sqlEx)
			throws SQLException {
		if (this.pooledConnection != null) {
			if (SQLError.SQL_STATE_COMMUNICATION_LINK_FAILURE.equals(sqlEx
					.getSQLState())) {
				this.pooledConnection.callConnectionEventListeners(
						MysqlPooledConnection.CONNECTION_ERROR_EVENT, sqlEx);
			}
		}

		throw sqlEx;
	}
	
	protected Map unwrappedInterfaces = null;
	protected ExceptionInterceptor exceptionInterceptor;

	protected WrapperBase(MysqlPooledConnection pooledConnection) {
		this.pooledConnection = pooledConnection;
		this.exceptionInterceptor = this.pooledConnection.getExceptionInterceptor();
	}
	
	protected class ConnectionErrorFiringInvocationHandler implements InvocationHandler {
		Object invokeOn = null;
		
		public ConnectionErrorFiringInvocationHandler(Object toInvokeOn) {
			invokeOn = toInvokeOn;
		}
		
		public Object invoke(Object proxy, Method method,
				Object[] args) throws Throwable {
			Object result = null;

			try {
				result = method.invoke(invokeOn, args);
				
				if (result != null) {
					result = proxyIfInterfaceIsJdbc(result, 
							result.getClass());
				}
			} catch (InvocationTargetException e) {
				if (e.getTargetException() instanceof SQLException) {
					checkAndFireConnectionError((SQLException) e
							.getTargetException());
				} else {
					throw e;
				}
			}

			return result;
		}
		
		/**
		 * Recursively checks for interfaces on the given object to determine
		 * if it implements a java.sql interface, and if so, proxies the 
		 * instance so that we can catch and fire SQL errors.
		 * @param toProxy
		 * @param clazz
		 * @return
		 */
		private Object proxyIfInterfaceIsJdbc(Object toProxy, Class clazz) {
			Class[] interfaces = clazz.getInterfaces();
			
			for (int i = 0; i < interfaces.length; i++) {
				String packageName = interfaces[i].getPackage().getName();
				
				if ("java.sql".equals(packageName) || 
						"javax.sql".equals(packageName)) {
					return Proxy.newProxyInstance(toProxy.getClass()
							.getClassLoader(), interfaces,
							new ConnectionErrorFiringInvocationHandler(toProxy));
				}
				
				return proxyIfInterfaceIsJdbc(toProxy, interfaces[i]);
			}
			
			return toProxy;
		}
	}
}