Commons DBCP example source code file (TransactionRegistry.java)

This example Commons DBCP source code file (TransactionRegistry.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons DBCP tags/keywords

connection, jdbc, map, nullpointerexception, nullpointerexception, sql, sqlexception, sqlexception, transaction, transaction, transactioncontext, transactioncontext, transactionregistry, unable, util, weakhashmap, xaresource, xaresource

The Commons DBCP TransactionRegistry.java source code

/**
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.commons.dbcp.managed;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.Map;
import java.util.WeakHashMap;

import javax.transaction.Status;
import javax.transaction.SystemException;
import javax.transaction.Transaction;
import javax.transaction.TransactionManager;
import javax.transaction.xa.XAResource;


/**
 * TransactionRegistry tracks Connections and XAResources in a transacted environment for a single XAConnectionFactory.
 * </p>
 * The TransactionRegistry hides the details of transaction processing from the existing DBCP pooling code, and gives
 * the ManagedConnection a way to enlist connections in a transaction, allowing for the maximal rescue of DBCP.
 *
 * @author Dain Sundstrom
 * @version $Revision$
 */
public class TransactionRegistry {
    private final TransactionManager transactionManager;
    private final Map caches = new WeakHashMap();
    private final Map xaResources = new WeakHashMap();

    /**
     * Creates a TransactionRegistry for the specified transaction manager.
     * @param transactionManager the transaction manager used to enlist connections
     */
    public TransactionRegistry(TransactionManager transactionManager) {
        this.transactionManager = transactionManager;
    }

    /**
     * Registers the association between a Connection and a XAResource.  When a connection
     * is enlisted in a transaction, it is actually the XAResource that is given to the transaction
     * manager.
     *
     * @param connection the JDBC connection
     * @param xaResource the XAResource which managed the connection within a transaction
     */
    public synchronized void registerConnection(Connection connection, XAResource xaResource) {
        if (connection == null) throw new NullPointerException("connection is null");
        if (xaResource == null) throw new NullPointerException("xaResource is null");
        xaResources.put(connection, xaResource);
    }

    /**
     * Gets the XAResource registered for the connection.
     * @param connection the connection
     * @return the XAResource registered for the connection; never null
     * @throws SQLException if the connection does not have a registered XAResource
     */
    public synchronized XAResource getXAResource(Connection connection) throws SQLException {
        if (connection == null) throw new NullPointerException("connection is null");
        XAResource xaResource = (XAResource) xaResources.get(connection);
        if (xaResource == null) {
            throw new SQLException("Connection does not have a registered XAResource " + connection);
        }
        return xaResource;
    }

    /**
     * Gets the active TransactionContext or null if not Transaction is active.
     * @return the active TransactionContext or null if not Transaction is active
     * @throws SQLException if an error occurs while fetching the transaction
     */
    public TransactionContext getActiveTransactionContext() throws SQLException {
        Transaction transaction = null;
        try {
            transaction = transactionManager.getTransaction();

            // was there a transaction?
            if (transaction == null) {
                return null;
            }

            // is it active
            int status = transaction.getStatus();
            if (status != Status.STATUS_ACTIVE && status != Status.STATUS_MARKED_ROLLBACK) {
                return null;
            }
        } catch (SystemException e) {
            throw (SQLException) new SQLException("Unable to determine current transaction ").initCause(e);
        }

        // register the the context (or create a new one)
        synchronized (this) {
            TransactionContext cache = (TransactionContext) caches.get(transaction);
            if (cache == null) {
                cache = new TransactionContext(this, transaction);
                caches.put(transaction, cache);
            }
            return cache;
        }
    }

    /**
     * Unregisters a destroyed connection from {@link TransactionRegistry}
     * @param connection
     */
    public synchronized void unregisterConnection(Connection connection) {
        xaResources.remove(connection);
    }
}