/*
* Copyright 2002-2008 the original author or authors.
*
* Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0
*
* 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.springframework.jca.cci.connection;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import javax.resource.ResourceException;
import javax.resource.cci.Connection;
import javax.resource.cci.ConnectionFactory;
/**
* Proxy for a target CCI {@link javax.resource.cci.ConnectionFactory}, adding
* awareness of Spring-managed transactions. Similar to a transactional JNDI
* ConnectionFactory as provided by a J2EE server.
*
* <p>Data access code that should remain unaware of Spring's data access support
* can work with this proxy to seamlessly participate in Spring-managed transactions.
* Note that the transaction manager, for example the {@link CciLocalTransactionManager},
* still needs to work with underlying ConnectionFactory, <i>not</i> with this proxy.
*
* <p><b>Make sure that TransactionAwareConnectionFactoryProxy is the outermost
* ConnectionFactory of a chain of ConnectionFactory proxies/adapters.</b>
* TransactionAwareConnectionFactoryProxy can delegate either directly to the
* target connection pool or to some intermediate proxy/adapter like
* {@link ConnectionSpecConnectionFactoryAdapter}.
*
* <p>Delegates to {@link ConnectionFactoryUtils} for automatically participating in
* thread-bound transactions, for example managed by {@link CciLocalTransactionManager}.
* <code>getConnection</code> calls and <code>close</code> calls on returned Connections
* will behave properly within a transaction, i.e. always operate on the transactional
* Connection. If not within a transaction, normal ConnectionFactory behavior applies.
*
* <p>This proxy allows data access code to work with the plain JCA CCI API and still
* participate in Spring-managed transactions, similar to CCI code in a J2EE/JTA
* environment. However, if possible, use Spring's ConnectionFactoryUtils, CciTemplate or
* CCI operation objects to get transaction participation even without a proxy for
* the target ConnectionFactory, avoiding the need to define such a proxy in the first place.
*
* <p><b>NOTE:</b> This ConnectionFactory proxy needs to return wrapped Connections
* in order to handle close calls properly. Therefore, the returned Connections cannot
* be cast to a native CCI Connection type or to a connection pool implementation type.
*
* @author Juergen Hoeller
* @since 1.2
* @see javax.resource.cci.ConnectionFactory#getConnection
* @see javax.resource.cci.Connection#close
* @see org.springframework.jca.cci.connection.ConnectionFactoryUtils#doGetConnection
* @see org.springframework.jca.cci.connection.ConnectionFactoryUtils#doReleaseConnection
*/
public class TransactionAwareConnectionFactoryProxy extends DelegatingConnectionFactory {
/**
* Create a new TransactionAwareConnectionFactoryProxy.
* @see #setTargetConnectionFactory
*/
public TransactionAwareConnectionFactoryProxy() {
}
/**
* Create a new TransactionAwareConnectionFactoryProxy.
* @param targetConnectionFactory the target ConnectionFactory
*/
public TransactionAwareConnectionFactoryProxy(ConnectionFactory targetConnectionFactory) {
setTargetConnectionFactory(targetConnectionFactory);
afterPropertiesSet();
}
/**
* Delegate to ConnectionFactoryUtils for automatically participating in Spring-managed
* transactions. Throws the original ResourceException, if any.
* @return a transactional Connection if any, a new one else
* @see org.springframework.jca.cci.connection.ConnectionFactoryUtils#doGetConnection
*/
public Connection getConnection() throws ResourceException {
Connection con = ConnectionFactoryUtils.doGetConnection(getTargetConnectionFactory());
return getTransactionAwareConnectionProxy(con, getTargetConnectionFactory());
}
/**
* Wrap the given Connection with a proxy that delegates every method call to it
* but delegates <code>close</code> calls to ConnectionFactoryUtils.
* @param target the original Connection to wrap
* @param cf ConnectionFactory that the Connection came from
* @return the wrapped Connection
* @see javax.resource.cci.Connection#close()
* @see org.springframework.jca.cci.connection.ConnectionFactoryUtils#doReleaseConnection
*/
protected Connection getTransactionAwareConnectionProxy(Connection target, ConnectionFactory cf) {
return (Connection) Proxy.newProxyInstance(
Connection.class.getClassLoader(),
new Class[] {Connection.class},
new TransactionAwareInvocationHandler(target, cf));
}
/**
* Invocation handler that delegates close calls on CCI Connections
* to ConnectionFactoryUtils for being aware of thread-bound transactions.
*/
private static class TransactionAwareInvocationHandler implements InvocationHandler {
private final Connection target;
private final ConnectionFactory connectionFactory;
public TransactionAwareInvocationHandler(Connection target, ConnectionFactory cf) {
this.target = target;
this.connectionFactory = cf;
}
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
// Invocation on Connection interface coming in...
if (method.getName().equals("equals")) {
// Only consider equal when proxies are identical.
return (proxy == args[0] ? Boolean.TRUE : Boolean.FALSE);
}
else if (method.getName().equals("hashCode")) {
// Use hashCode of Connection proxy.
return new Integer(System.identityHashCode(proxy));
}
else if (method.getName().equals("getLocalTransaction")) {
if (ConnectionFactoryUtils.isConnectionTransactional(this.target, this.connectionFactory)) {
throw new javax.resource.spi.IllegalStateException(
"Local transaction handling not allowed within a managed transaction");
}
}
else if (method.getName().equals("close")) {
// Handle close method: only close if not within a transaction.
ConnectionFactoryUtils.doReleaseConnection(this.target, this.connectionFactory);
return null;
}
// Invoke method on target Connection.
try {
return method.invoke(this.target, args);
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
}
}
}