Commons DBCP example source code file (SharedPoolDataSource.java)

This example Commons DBCP source code file (SharedPoolDataSource.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

generickeyedobjectpool, io, ioexception, jdbc, keyedcpdsconnectionfactory, naming, namingexception, namingexception, pooledconnectionandinfo, sharedpooldatasource, sharedpooldatasource, sql, sqlexception, sqlexception, sqlnestedexception, string, string, userpasskey

The Commons DBCP SharedPoolDataSource.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.datasources;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.sql.Connection;
import java.sql.SQLException;

import javax.naming.NamingException;
import javax.naming.Reference;
import javax.naming.StringRefAddr;
import javax.sql.ConnectionPoolDataSource;

import org.apache.commons.pool.KeyedObjectPool;
import org.apache.commons.pool.impl.GenericKeyedObjectPool;
import org.apache.commons.pool.impl.GenericObjectPool;
import org.apache.commons.dbcp.SQLNestedException;

/**
 * <p>A pooling DataSource appropriate for deployment within
 * J2EE environment.  There are many configuration options, most of which are
 * defined in the parent class. All users (based on username) share a single 
 * maximum number of Connections in this datasource.</p>
 * 
 * <p>User passwords can be changed without re-initializing the datasource.
 * When a <code>getConnection(username, password) request is processed 
 * with a password that is different from those used to create connections in the
 * pool associated with <code>username, an attempt is made to create a
 * new connection using the supplied password and if this succeeds, idle connections
 * created using the old password are destroyed and new connections are created
 * using the new password.</p>
 *
 * @author John D. McNally
 * @version $Revision: 907288 $ $Date: 2010-02-06 14:42:58 -0500 (Sat, 06 Feb 2010) $
 */
public class SharedPoolDataSource
    extends InstanceKeyDataSource {

    private static final long serialVersionUID = -8132305535403690372L;

    private int maxActive = GenericObjectPool.DEFAULT_MAX_ACTIVE;
    private int maxIdle = GenericObjectPool.DEFAULT_MAX_IDLE;
    private int maxWait = (int)Math.min(Integer.MAX_VALUE,
        GenericObjectPool.DEFAULT_MAX_WAIT);
    private transient KeyedObjectPool pool = null;
    private transient KeyedCPDSConnectionFactory factory = null;

    /**
     * Default no-arg constructor for Serialization
     */
    public SharedPoolDataSource() {
    }

    /**
     * Close pool being maintained by this datasource.
     */
    public void close() throws Exception {
        if (pool != null) {
            pool.close();
        }
        InstanceKeyObjectFactory.removeInstance(instanceKey);
    }

    // -------------------------------------------------------------------
    // Properties

    /**
     * The maximum number of active connections that can be allocated from
     * this pool at the same time, or non-positive for no limit.
     */
    public int getMaxActive() {
        return (this.maxActive);
    }

    /**
     * The maximum number of active connections that can be allocated from
     * this pool at the same time, or non-positive for no limit.
     * The default is 8.
     */
    public void setMaxActive(int maxActive) {
        assertInitializationAllowed();
        this.maxActive = maxActive;
    }

    /**
     * The maximum number of active connections that can remain idle in the
     * pool, without extra ones being released, or negative for no limit.
     */
    public int getMaxIdle() {
        return (this.maxIdle);
    }

    /**
     * The maximum number of active connections that can remain idle in the
     * pool, without extra ones being released, or negative for no limit.
     * The default is 8.
     */
    public void setMaxIdle(int maxIdle) {
        assertInitializationAllowed();
        this.maxIdle = maxIdle;
    }

    /**
     * The maximum number of milliseconds that the pool will wait (when there
     * are no available connections) for a connection to be returned before
     * throwing an exception, or -1 to wait indefinitely.  Will fail 
     * immediately if value is 0.
     * The default is -1.
     */
    public int getMaxWait() {
        return (this.maxWait);
    }

    /**
     * The maximum number of milliseconds that the pool will wait (when there
     * are no available connections) for a connection to be returned before
     * throwing an exception, or -1 to wait indefinitely.  Will fail 
     * immediately if value is 0.
     * The default is -1.
     */
    public void setMaxWait(int maxWait) {
        assertInitializationAllowed();
        this.maxWait = maxWait;
    }

    // ----------------------------------------------------------------------
    // Instrumentation Methods

    /**
     * Get the number of active connections in the pool.
     */
    public int getNumActive() {
        return (pool == null) ? 0 : pool.getNumActive();
    }

    /**
     * Get the number of idle connections in the pool.
     */
    public int getNumIdle() {
        return (pool == null) ? 0 : pool.getNumIdle();
    }

    // ----------------------------------------------------------------------
    // Inherited abstract methods

    protected PooledConnectionAndInfo 
        getPooledConnectionAndInfo(String username, String password)
        throws SQLException {
        
        synchronized(this) {
            if (pool == null) {
                try {
                    registerPool(username, password);
                } catch (NamingException e) {
                    throw new SQLNestedException("RegisterPool failed", e);
                }
            }
        }

        PooledConnectionAndInfo info = null;
        
        UserPassKey key = new UserPassKey(username, password);
        
        try {
            info = (PooledConnectionAndInfo) pool.borrowObject(key);
        }
        catch (Exception e) {
            throw new SQLNestedException(
                    "Could not retrieve connection info from pool", e);
        }
        return info;
    }
    
    protected PooledConnectionManager getConnectionManager(UserPassKey upkey)  {
        return factory;
    }

    /**
     * Returns a <code>SharedPoolDataSource {@link Reference}.
     * 
     * @since 1.2.2
     */
    public Reference getReference() throws NamingException {
        Reference ref = new Reference(getClass().getName(),
            SharedPoolDataSourceFactory.class.getName(), null);
        ref.add(new StringRefAddr("instanceKey", instanceKey));
        return ref;
    }
    
    private void registerPool(
        String username, String password) 
        throws javax.naming.NamingException, SQLException {

        ConnectionPoolDataSource cpds = testCPDS(username, password);

        // Create an object pool to contain our PooledConnections
        GenericKeyedObjectPool tmpPool = new GenericKeyedObjectPool(null);
        tmpPool.setMaxActive(getMaxActive());
        tmpPool.setMaxIdle(getMaxIdle());
        tmpPool.setMaxWait(getMaxWait());
        tmpPool.setWhenExhaustedAction(whenExhaustedAction(maxActive, maxWait));
        tmpPool.setTestOnBorrow(getTestOnBorrow());
        tmpPool.setTestOnReturn(getTestOnReturn());
        tmpPool.setTimeBetweenEvictionRunsMillis(
            getTimeBetweenEvictionRunsMillis());
        tmpPool.setNumTestsPerEvictionRun(getNumTestsPerEvictionRun());
        tmpPool.setMinEvictableIdleTimeMillis(getMinEvictableIdleTimeMillis());
        tmpPool.setTestWhileIdle(getTestWhileIdle());
        pool = tmpPool;
        // Set up the factory we will use (passing the pool associates
        // the factory with the pool, so we do not have to do so
        // explicitly)
        factory = new KeyedCPDSConnectionFactory(cpds, pool, getValidationQuery(),
                                       isRollbackAfterValidation());
    }

    protected void setupDefaults(Connection con, String username) throws SQLException {
        boolean defaultAutoCommit = isDefaultAutoCommit();
        if (con.getAutoCommit() != defaultAutoCommit) {
            con.setAutoCommit(defaultAutoCommit);
        }

        int defaultTransactionIsolation = getDefaultTransactionIsolation();
        if (defaultTransactionIsolation != UNKNOWN_TRANSACTIONISOLATION) {
            con.setTransactionIsolation(defaultTransactionIsolation);
        }

        boolean defaultReadOnly = isDefaultReadOnly();
        if (con.isReadOnly() != defaultReadOnly) {
            con.setReadOnly(defaultReadOnly);
        }
    }

    /**
     * Supports Serialization interface.
     *
     * @param in a <code>java.io.ObjectInputStream value
     * @exception IOException if an error occurs
     * @exception ClassNotFoundException if an error occurs
     */
    private void readObject(ObjectInputStream in)
        throws IOException, ClassNotFoundException {
        try 
        {
            in.defaultReadObject();
            SharedPoolDataSource oldDS = (SharedPoolDataSource)
                new SharedPoolDataSourceFactory()
                    .getObjectInstance(getReference(), null, null, null);
            this.pool = oldDS.pool;
        }
        catch (NamingException e)
        {
            throw new IOException("NamingException: " + e);
        }
    }
}