/*
* 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.NotSupportedException;
import javax.resource.ResourceException;
import javax.resource.cci.Connection;
import javax.resource.cci.ConnectionFactory;
import javax.resource.cci.ConnectionSpec;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.util.Assert;
/**
* A CCI ConnectionFactory adapter that returns the same Connection on all
* <code>getConnection</code> calls, and ignores calls to
* <code>Connection.close()</code>.
*
* <p>Useful for testing and standalone environments, to keep using the same
* Connection for multiple CciTemplate calls, without having a pooling
* ConnectionFactory, also spanning any number of transactions.
*
* <p>You can either pass in a CCI Connection directly, or let this
* factory lazily create a Connection via a given target ConnectionFactory.
*
* @author Juergen Hoeller
* @since 1.2
* @see #getConnection()
* @see javax.resource.cci.Connection#close()
* @see org.springframework.jca.cci.core.CciTemplate
*/
public class SingleConnectionFactory extends DelegatingConnectionFactory implements DisposableBean {
protected final Log logger = LogFactory.getLog(getClass());
/** Wrapped Connection */
private Connection target;
/** Proxy Connection */
private Connection connection;
/** Synchronization monitor for the shared Connection */
private final Object connectionMonitor = new Object();
/**
* Create a new SingleConnectionFactory for bean-style usage.
* @see #setTargetConnectionFactory
*/
public SingleConnectionFactory() {
}
/**
* Create a new SingleConnectionFactory that always returns the
* given Connection.
* @param target the single Connection
*/
public SingleConnectionFactory(Connection target) {
Assert.notNull(target, "Target Connection must not be null");
this.target = target;
this.connection = getCloseSuppressingConnectionProxy(target);
}
/**
* Create a new SingleConnectionFactory that always returns a single
* Connection which it will lazily create via the given target
* ConnectionFactory.
* @param targetConnectionFactory the target ConnectionFactory
*/
public SingleConnectionFactory(ConnectionFactory targetConnectionFactory) {
Assert.notNull(targetConnectionFactory, "Target ConnectionFactory must not be null");
setTargetConnectionFactory(targetConnectionFactory);
}
/**
* Make sure a Connection or ConnectionFactory has been set.
*/
@Override
public void afterPropertiesSet() {
if (this.connection == null && getTargetConnectionFactory() == null) {
throw new IllegalArgumentException("Connection or 'targetConnectionFactory' is required");
}
}
@Override
public Connection getConnection() throws ResourceException {
synchronized (this.connectionMonitor) {
if (this.connection == null) {
initConnection();
}
return this.connection;
}
}
@Override
public Connection getConnection(ConnectionSpec connectionSpec) throws ResourceException {
throw new NotSupportedException(
"SingleConnectionFactory does not support custom ConnectionSpec");
}
/**
* Close the underlying Connection.
* The provider of this ConnectionFactory needs to care for proper shutdown.
* <p>As this bean implements DisposableBean, a bean factory will
* automatically invoke this on destruction of its cached singletons.
*/
public void destroy() {
resetConnection();
}
/**
* Initialize the single underlying Connection.
* <p>Closes and reinitializes the Connection if an underlying
* Connection is present already.
* @throws javax.resource.ResourceException if thrown by CCI API methods
*/
public void initConnection() throws ResourceException {
if (getTargetConnectionFactory() == null) {
throw new IllegalStateException(
"'targetConnectionFactory' is required for lazily initializing a Connection");
}
synchronized (this.connectionMonitor) {
if (this.target != null) {
closeConnection(this.target);
}
this.target = doCreateConnection();
prepareConnection(this.target);
if (logger.isInfoEnabled()) {
logger.info("Established shared CCI Connection: " + this.target);
}
this.connection = getCloseSuppressingConnectionProxy(this.target);
}
}
/**
* Reset the underlying shared Connection, to be reinitialized on next access.
*/
public void resetConnection() {
synchronized (this.connectionMonitor) {
if (this.target != null) {
closeConnection(this.target);
}
this.target = null;
this.connection = null;
}
}
/**
* Create a CCI Connection via this template's ConnectionFactory.
* @return the new CCI Connection
* @throws javax.resource.ResourceException if thrown by CCI API methods
*/
protected Connection doCreateConnection() throws ResourceException {
return getTargetConnectionFactory().getConnection();
}
/**
* Prepare the given Connection before it is exposed.
* <p>The default implementation is empty. Can be overridden in subclasses.
* @param con the Connection to prepare
*/
protected void prepareConnection(Connection con) throws ResourceException {
}
/**
* Close the given Connection.
* @param con the Connection to close
*/
protected void closeConnection(Connection con) {
try {
con.close();
}
catch (Throwable ex) {
logger.warn("Could not close shared CCI Connection", ex);
}
}
/**
* Wrap the given Connection with a proxy that delegates every method call to it
* but suppresses close calls. This is useful for allowing application code to
* handle a special framework Connection just like an ordinary Connection from a
* CCI ConnectionFactory.
* @param target the original Connection to wrap
* @return the wrapped Connection
*/
protected Connection getCloseSuppressingConnectionProxy(Connection target) {
return (Connection) Proxy.newProxyInstance(
Connection.class.getClassLoader(),
new Class[] {Connection.class},
new CloseSuppressingInvocationHandler(target));
}
/**
* Invocation handler that suppresses close calls on CCI Connections.
*/
private static class CloseSuppressingInvocationHandler implements InvocationHandler {
private final Connection target;
private CloseSuppressingInvocationHandler(Connection target) {
this.target = target;
}
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
if (method.getName().equals("equals")) {
// Only consider equal when proxies are identical.
return (proxy == args[0]);
}
else if (method.getName().equals("hashCode")) {
// Use hashCode of Connection proxy.
return System.identityHashCode(proxy);
}
else if (method.getName().equals("close")) {
// Handle close method: don't pass the call on.
return null;
}
try {
return method.invoke(this.target, args);
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
}
}
}
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