Commons DBCP example source code file (PoolingDriver.java)

This example Commons DBCP source code file (PoolingDriver.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

callablestatement, connection, connection, delegatingcallablestatement, delegatingpreparedstatement, io, jdbc, objectpool, objectpool, poolguardconnectionwrapper, preparedstatement, sax, sql, sqlexception, sqlexception, statement, string, string, util

The Commons DBCP PoolingDriver.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;

import java.io.IOException;
import java.io.InputStream;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.DriverPropertyInfo;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.SQLWarning;
import java.sql.Statement;
import java.util.HashMap;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Properties;
import java.util.Set;

import org.apache.commons.jocl.JOCLContentHandler;
import org.apache.commons.pool.ObjectPool;
import org.xml.sax.SAXException;


/**
 * A {@link Driver} implementation that obtains
 * {@link Connection}s from a registered
 * {@link ObjectPool}.
 *
 * @author Rodney Waldhoff
 * @author Dirk Verbeeck
 * @version $Revision: 902692 $ $Date: 2010-01-24 22:28:54 -0500 (Sun, 24 Jan 2010) $
 */
public class PoolingDriver implements Driver {
    /** Register myself with the {@link DriverManager}. */
    static {
        try {
            DriverManager.registerDriver(new PoolingDriver());
        } catch(Exception e) {
        }
    }

    /** The map of registered pools. */
    protected static final HashMap _pools = new HashMap();

    /** Controls access to the underlying connection */
    private static boolean accessToUnderlyingConnectionAllowed = false; 

    public PoolingDriver() {
    }

    /**
     * Returns the value of the accessToUnderlyingConnectionAllowed property.
     * 
     * @return true if access to the underlying is allowed, false otherwise.
     */
    public static synchronized boolean isAccessToUnderlyingConnectionAllowed() {
        return accessToUnderlyingConnectionAllowed;
    }

    /**
     * Sets the value of the accessToUnderlyingConnectionAllowed property.
     * It controls if the PoolGuard allows access to the underlying connection.
     * (Default: false)
     * 
     * @param allow Access to the underlying connection is granted when true.
     */
    public static synchronized void setAccessToUnderlyingConnectionAllowed(boolean allow) {
        accessToUnderlyingConnectionAllowed = allow;
    }

    /**
     * WARNING: This method throws DbcpExceptions (RuntimeExceptions)
     * and will be replaced by the protected getConnectionPool method.
     * 
     * @deprecated This will be removed in a future version of DBCP.
     */
    public synchronized ObjectPool getPool(String name) {
        try {
            return getConnectionPool(name);
        }
        catch (Exception e) {
            throw new DbcpException(e);
        }
    }
    
    public synchronized ObjectPool getConnectionPool(String name) throws SQLException {
        ObjectPool pool = (ObjectPool)(_pools.get(name));
        if(null == pool) {
            InputStream in = this.getClass().getResourceAsStream(String.valueOf(name) + ".jocl");
            if (in == null) {
                in = Thread.currentThread().getContextClassLoader(
                        ).getResourceAsStream(String.valueOf(name) + ".jocl");
            }
            if(null != in) {
                JOCLContentHandler jocl = null;
                try {
                    jocl = JOCLContentHandler.parse(in);
                }
                catch (SAXException e) {
                    throw (SQLException) new SQLException("Could not parse configuration file").initCause(e);
                }
                catch (IOException e) {
                    throw (SQLException) new SQLException("Could not load configuration file").initCause(e);
                }
                if(jocl.getType(0).equals(String.class)) {
                    pool = getPool((String)(jocl.getValue(0)));
                    if(null != pool) {
                        registerPool(name,pool);
                    }
                } else {
                    pool = ((PoolableConnectionFactory)(jocl.getValue(0))).getPool();
                    if(null != pool) {
                        registerPool(name,pool);
                    }
                }
            }
            else {
                throw new SQLException("Configuration file not found");
            }
        }
        return pool;
    }

    public synchronized void registerPool(String name, ObjectPool pool) {
        _pools.put(name,pool);
    }

    public synchronized void closePool(String name) throws SQLException {
        ObjectPool pool = (ObjectPool) _pools.get(name);
        if (pool != null) {
            _pools.remove(name);
            try {
                pool.close();
            }
            catch (Exception e) {
                throw (SQLException) new SQLException("Error closing pool " + name).initCause(e);
            }
        }
    }
    
    public synchronized String[] getPoolNames(){
        Set names = _pools.keySet();
        return (String[]) names.toArray(new String[names.size()]);
    }

    public boolean acceptsURL(String url) throws SQLException {
        try {
            return url.startsWith(URL_PREFIX);
        } catch(NullPointerException e) {
            return false;
        }
    }

    public Connection connect(String url, Properties info) throws SQLException {
        if(acceptsURL(url)) {
            ObjectPool pool = getConnectionPool(url.substring(URL_PREFIX_LEN));
            if(null == pool) {
                throw new SQLException("No pool found for " + url + ".");
            } else {
                try {
                    Connection conn = (Connection)(pool.borrowObject());
                    if (conn != null) {
                        conn = new PoolGuardConnectionWrapper(pool, conn);
                    } 
                    return conn;
                } catch(SQLException e) {
                    throw e;
                } catch(NoSuchElementException e) {
                    throw (SQLException) new SQLException("Cannot get a connection, pool error: " + e.getMessage()).initCause(e);
                } catch(RuntimeException e) {
                    throw e;
                } catch(Exception e) {
                    throw (SQLException) new SQLException("Cannot get a connection, general error: " + e.getMessage()).initCause(e);
                }
            }
        } else {
            return null;
        }
    }

    /**
     * Invalidates the given connection.
     * 
     * @param conn connection to invalidate
     * @throws SQLException if the connection is not a 
     * <code>PoolGuardConnectionWrapper or an error occurs invalidating
     * the connection
     * @since 1.2.2
     */
    public void invalidateConnection(Connection conn) throws SQLException {
        if (conn instanceof PoolGuardConnectionWrapper) { // normal case
            PoolGuardConnectionWrapper pgconn = (PoolGuardConnectionWrapper) conn;
            ObjectPool pool = pgconn.pool;
            Connection delegate = pgconn.delegate;
            try {
                pool.invalidateObject(delegate);
            } 
            catch (Exception e) { 
            }
            pgconn.delegate = null;
        }
        else {
            throw new SQLException("Invalid connection class");
        }
    }

    public int getMajorVersion() {
        return MAJOR_VERSION;
    }

    public int getMinorVersion() {
        return MINOR_VERSION;
    }

    public boolean jdbcCompliant() {
        return true;
    }

    public DriverPropertyInfo[] getPropertyInfo(String url, Properties info) {
        return new DriverPropertyInfo[0];
    }

    /** My URL prefix */
    protected static final String URL_PREFIX = "jdbc:apache:commons:dbcp:";
    protected static final int URL_PREFIX_LEN = URL_PREFIX.length();

    // version numbers
    protected static final int MAJOR_VERSION = 1;
    protected static final int MINOR_VERSION = 0;

    /**
     * PoolGuardConnectionWrapper is a Connection wrapper that makes sure a 
     * closed connection cannot be used anymore.
     */
    static private class PoolGuardConnectionWrapper extends DelegatingConnection {

        private final ObjectPool pool;
        private Connection delegate;
    
        PoolGuardConnectionWrapper(ObjectPool pool, Connection delegate) {
            super(delegate);
            this.pool = pool;
            this.delegate = delegate;
        }

        protected void checkOpen() throws SQLException {
            if(delegate == null) {
                throw new SQLException("Connection is closed.");
            }
        }

        public void close() throws SQLException {
            if (delegate != null) {
                this.delegate.close();
                this.delegate = null;
                super.setDelegate(null);
            }
        }

        public boolean isClosed() throws SQLException {
            if (delegate == null) {
                return true;
            }
            return delegate.isClosed();
        }

        public void clearWarnings() throws SQLException {
            checkOpen();
            delegate.clearWarnings();
        }

        public void commit() throws SQLException {
            checkOpen();
            delegate.commit();
        }

        public Statement createStatement() throws SQLException {
            checkOpen();
            return new DelegatingStatement(this, delegate.createStatement());
        }

        public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {
            checkOpen();
            return new DelegatingStatement(this, delegate.createStatement(resultSetType, resultSetConcurrency));
        }

        public boolean equals(Object obj) {
            if (delegate == null){
                return false;
            }
            return delegate.equals(obj);
        }

        public boolean getAutoCommit() throws SQLException {
            checkOpen();
            return delegate.getAutoCommit();
        }

        public String getCatalog() throws SQLException {
            checkOpen();
            return delegate.getCatalog();
        }

        public DatabaseMetaData getMetaData() throws SQLException {
            checkOpen();
            return delegate.getMetaData();
        }

        public int getTransactionIsolation() throws SQLException {
            checkOpen();
            return delegate.getTransactionIsolation();
        }

        public Map getTypeMap() throws SQLException {
            checkOpen();
            return delegate.getTypeMap();
        }

        public SQLWarning getWarnings() throws SQLException {
            checkOpen();
            return delegate.getWarnings();
        }

        public int hashCode() {
            if (delegate == null){
                return 0;
            }
            return delegate.hashCode();
        }

        public boolean isReadOnly() throws SQLException {
            checkOpen();
            return delegate.isReadOnly();
        }

        public String nativeSQL(String sql) throws SQLException {
            checkOpen();
            return delegate.nativeSQL(sql);
        }

        public CallableStatement prepareCall(String sql) throws SQLException {
            checkOpen();
            return new DelegatingCallableStatement(this, delegate.prepareCall(sql));
        }

        public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
            checkOpen();
            return new DelegatingCallableStatement(this, delegate.prepareCall(sql, resultSetType, resultSetConcurrency));
        }

        public PreparedStatement prepareStatement(String sql) throws SQLException {
            checkOpen();
            return new DelegatingPreparedStatement(this, delegate.prepareStatement(sql));
        }

        public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
            checkOpen();
            return new DelegatingPreparedStatement(this, delegate.prepareStatement(sql, resultSetType, resultSetConcurrency));
        }

        public void rollback() throws SQLException {
            checkOpen();
            delegate.rollback();
        }

        public void setAutoCommit(boolean autoCommit) throws SQLException {
            checkOpen();
            delegate.setAutoCommit(autoCommit);
        }

        public void setCatalog(String catalog) throws SQLException {
            checkOpen();
            delegate.setCatalog(catalog);
        }

        public void setReadOnly(boolean readOnly) throws SQLException {
            checkOpen();
            delegate.setReadOnly(readOnly);
        }

        public void setTransactionIsolation(int level) throws SQLException {
            checkOpen();
            delegate.setTransactionIsolation(level);
        }

        public void setTypeMap(Map map) throws SQLException {
            checkOpen();
            delegate.setTypeMap(map);
        }

        public String toString() {
            if (delegate == null){
                return "NULL";
            }
            return delegate.toString();
        }

        public int getHoldability() throws SQLException {
            checkOpen();
            return delegate.getHoldability();
        }
    
        public void setHoldability(int holdability) throws SQLException {
            checkOpen();
            delegate.setHoldability(holdability);
        }

        public java.sql.Savepoint setSavepoint() throws SQLException {
            checkOpen();
            return delegate.setSavepoint();
        }

        public java.sql.Savepoint setSavepoint(String name) throws SQLException {
            checkOpen();
            return delegate.setSavepoint(name);
        }

        public void releaseSavepoint(java.sql.Savepoint savepoint) throws SQLException {
            checkOpen();
            delegate.releaseSavepoint(savepoint);
        }

        public void rollback(java.sql.Savepoint savepoint) throws SQLException {
            checkOpen();
            delegate.rollback(savepoint);
        }

        public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
            checkOpen();
            return new DelegatingStatement(this, delegate.createStatement(resultSetType, resultSetConcurrency, resultSetHoldability));
        }

        public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
            checkOpen();
            return new DelegatingCallableStatement(this, delegate.prepareCall(sql, resultSetType, resultSetConcurrency, resultSetHoldability));
        }

        public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {
            checkOpen();
            return new DelegatingPreparedStatement(this, delegate.prepareStatement(sql, autoGeneratedKeys));
        }

        public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
            checkOpen();
            return new DelegatingPreparedStatement(this, delegate.prepareStatement(sql, resultSetType, resultSetConcurrency, resultSetHoldability));
        }

        public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {
            checkOpen();
            return new DelegatingPreparedStatement(this, delegate.prepareStatement(sql, columnIndexes));
        }

        public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {
            checkOpen();
            return new DelegatingPreparedStatement(this, delegate.prepareStatement(sql, columnNames));
        }

        /**
         * @see org.apache.commons.dbcp.DelegatingConnection#getDelegate()
         */
        public Connection getDelegate() {
            if (isAccessToUnderlyingConnectionAllowed()) {
                return super.getDelegate();
            } else {
                return null;
            }
        }

        /**
         * @see org.apache.commons.dbcp.DelegatingConnection#getInnermostDelegate()
         */
        public Connection getInnermostDelegate() {
            if (isAccessToUnderlyingConnectionAllowed()) {
                return super.getInnermostDelegate();
            } else {
                return null;
            }
        }
    }
}