Java tutorial
/* * Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.sql; import java.sql.Connection; import java.sql.SQLException; /** * An object that provides hooks for connection pool management. * A <code>PooledConnection</code> object * represents a physical connection to a data source. The connection * can be recycled rather than being closed when an application is * finished with it, thus reducing the number of connections that * need to be made. * <P> * An application programmer does not use the <code>PooledConnection</code> * interface directly; rather, it is used by a middle tier infrastructure * that manages the pooling of connections. * <P> * When an application calls the method <code>DataSource.getConnection</code>, * it gets back a <code>Connection</code> object. If connection pooling is * being done, that <code>Connection</code> object is actually a handle to * a <code>PooledConnection</code> object, which is a physical connection. * <P> * The connection pool manager, typically the application server, maintains * a pool of <code>PooledConnection</code> objects. If there is a * <code>PooledConnection</code> object available in the pool, the * connection pool manager returns a <code>Connection</code> object that * is a handle to that physical connection. * If no <code>PooledConnection</code> object is available, the * connection pool manager calls the <code>ConnectionPoolDataSource</code> * method <code>getPoolConnection</code> to create a new physical connection. The * JDBC driver implementing <code>ConnectionPoolDataSource</code> creates a * new <code>PooledConnection</code> object and returns a handle to it. * <P> * When an application closes a connection, it calls the <code>Connection</code> * method <code>close</code>. When connection pooling is being done, * the connection pool manager is notified because it has registered itself as * a <code>ConnectionEventListener</code> object using the * <code>ConnectionPool</code> method <code>addConnectionEventListener</code>. * The connection pool manager deactivates the handle to * the <code>PooledConnection</code> object and returns the * <code>PooledConnection</code> object to the pool of connections so that * it can be used again. Thus, when an application closes its connection, * the underlying physical connection is recycled rather than being closed. * <p> * If the connection pool manager wraps or provides a proxy to the logical * handle returned from a call to {@code PoolConnection.getConnection}, the pool * manager must do one of the following when the connection pool manager * closes or returns the {@code PooledConnection} to the pool in response to * the application calling {@code Connection.close}: * <ul> * <li>call {@code endRequest} on the logical {@code Connection} handle * <li>call {@code close} on the logical {@code Connection} handle * </ul> * <p> * The physical connection is not closed until the connection pool manager * calls the <code>PooledConnection</code> method <code>close</code>. * This method is generally called to have an orderly shutdown of the server or * if a fatal error has made the connection unusable. * * <p> * A connection pool manager is often also a statement pool manager, maintaining * a pool of <code>PreparedStatement</code> objects. * When an application closes a prepared statement, it calls the * <code>PreparedStatement</code> * method <code>close</code>. When <code>Statement</code> pooling is being done, * the pool manager is notified because it has registered itself as * a <code>StatementEventListener</code> object using the * <code>ConnectionPool</code> method <code>addStatementEventListener</code>. * Thus, when an application closes its <code>PreparedStatement</code>, * the underlying prepared statement is recycled rather than being closed. * * @since 1.4 */ public interface PooledConnection { /** * Creates and returns a <code>Connection</code> object that is a handle * for the physical connection that * this <code>PooledConnection</code> object represents. * The connection pool manager calls this method when an application has * called the method <code>DataSource.getConnection</code> and there are * no <code>PooledConnection</code> objects available. See the * {@link PooledConnection interface description} for more information. * * @return a <code>Connection</code> object that is a handle to * this <code>PooledConnection</code> object * @exception SQLException if a database access error occurs * @exception java.sql.SQLFeatureNotSupportedException if the JDBC driver does not support * this method * @since 1.4 */ Connection getConnection() throws SQLException; /** * Closes the physical connection that this <code>PooledConnection</code> * object represents. An application never calls this method directly; * it is called by the connection pool module, or manager. * <P> * See the {@link PooledConnection interface description} for more * information. * * @exception SQLException if a database access error occurs * @exception java.sql.SQLFeatureNotSupportedException if the JDBC driver does not support * this method * @since 1.4 */ void close() throws SQLException; /** * Registers the given event listener so that it will be notified * when an event occurs on this <code>PooledConnection</code> object. * * @param listener a component, usually the connection pool manager, * that has implemented the * <code>ConnectionEventListener</code> interface and wants to be * notified when the connection is closed or has an error * @see #removeConnectionEventListener */ void addConnectionEventListener(ConnectionEventListener listener); /** * Removes the given event listener from the list of components that * will be notified when an event occurs on this * <code>PooledConnection</code> object. * * @param listener a component, usually the connection pool manager, * that has implemented the * <code>ConnectionEventListener</code> interface and * been registered with this <code>PooledConnection</code> object as * a listener * @see #addConnectionEventListener */ void removeConnectionEventListener(ConnectionEventListener listener); /** * Registers a <code>StatementEventListener</code> with this <code>PooledConnection</code> object. Components that * wish to be notified when <code>PreparedStatement</code>s created by the * connection are closed or are detected to be invalid may use this method * to register a <code>StatementEventListener</code> with this <code>PooledConnection</code> object. * * @param listener an component which implements the <code>StatementEventListener</code> * interface that is to be registered with this <code>PooledConnection</code> object * * @since 1.6 */ public void addStatementEventListener(StatementEventListener listener); /** * Removes the specified <code>StatementEventListener</code> from the list of * components that will be notified when the driver detects that a * <code>PreparedStatement</code> has been closed or is invalid. * * @param listener the component which implements the * <code>StatementEventListener</code> interface that was previously * registered with this <code>PooledConnection</code> object * * @since 1.6 */ public void removeStatementEventListener(StatementEventListener listener); }