1 /*
   2  * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package javax.sql;
  27 
  28 import java.sql.Connection;
  29 import java.sql.SQLException;
  30 
  31 /**
  32  * An object that provides hooks for connection pool management.
  33  * A <code>PooledConnection</code> object
  34  * represents a physical connection to a data source.  The connection
  35  * can be recycled rather than being closed when an application is
  36  * finished with it, thus reducing the number of connections that
  37  * need to be made.
  38  * <P>
  39  * An application programmer does not use the <code>PooledConnection</code>
  40  * interface directly; rather, it is used by a middle tier infrastructure
  41  * that manages the pooling of connections.
  42  * <P>
  43  * When an application calls the method <code>DataSource.getConnection</code>,
  44  * it gets back a <code>Connection</code> object.  If connection pooling is
  45  * being done, that <code>Connection</code> object is actually a handle to
  46  * a <code>PooledConnection</code> object, which is a physical connection.
  47  * <P>
  48  * The connection pool manager, typically the application server, maintains
  49  * a pool of <code>PooledConnection</code> objects.  If there is a
  50  * <code>PooledConnection</code> object available in the pool, the
  51  * connection pool manager returns a <code>Connection</code> object that
  52  * is a handle to that physical connection.
  53  * If no <code>PooledConnection</code> object is available, the
  54  * connection pool manager calls the <code>ConnectionPoolDataSource</code>
  55  * method <code>getPoolConnection</code> to create a new physical connection.  The
  56  *  JDBC driver implementing <code>ConnectionPoolDataSource</code> creates a
  57  *  new <code>PooledConnection</code> object and returns a handle to it.
  58  * <P>
  59  * When an application closes a connection, it calls the <code>Connection</code>
  60  * method <code>close</code>. When connection pooling is being done,
  61  * the connection pool manager is notified because it has registered itself as
  62  * a <code>ConnectionEventListener</code> object using the
  63  * <code>ConnectionPool</code> method <code>addConnectionEventListener</code>.
  64  * The connection pool manager deactivates the handle to
  65  * the <code>PooledConnection</code> object and  returns the
  66  * <code>PooledConnection</code> object to the pool of connections so that
  67  * it can be used again.  Thus, when an application closes its connection,
  68  * the underlying physical connection is recycled rather than being closed.
  69  * <P>
  70  * The physical connection is not closed until the connection pool manager
  71  * calls the <code>PooledConnection</code> method <code>close</code>.
  72  * This method is generally called to have an orderly shutdown of the server or
  73  * if a fatal error has made the connection unusable.
  74  *
  75  * <p>
  76  * A connection pool manager is often also a statement pool manager, maintaining
  77  *  a pool of <code>PreparedStatement</code> objects.
  78  *  When an application closes a prepared statement, it calls the
  79  *  <code>PreparedStatement</code>
  80  * method <code>close</code>. When <code>Statement</code> pooling is being done,
  81  * the pool manager is notified because it has registered itself as
  82  * a <code>StatementEventListener</code> object using the
  83  * <code>ConnectionPool</code> method <code>addStatementEventListener</code>.
  84  *  Thus, when an application closes its  <code>PreparedStatement</code>,
  85  * the underlying prepared statement is recycled rather than being closed.
  86  * <P>
  87  *
  88  * @since 1.4
  89  */
  90 
  91 public interface PooledConnection {
  92 
  93   /**
  94    * Creates and returns a <code>Connection</code> object that is a handle
  95    * for the physical connection that
  96    * this <code>PooledConnection</code> object represents.
  97    * The connection pool manager calls this method when an application has
  98    * called the method <code>DataSource.getConnection</code> and there are
  99    * no <code>PooledConnection</code> objects available. See the
 100    * {@link PooledConnection interface description} for more information.
 101    *
 102    * @return  a <code>Connection</code> object that is a handle to
 103    *          this <code>PooledConnection</code> object
 104    * @exception SQLException if a database access error occurs
 105    * @exception java.sql.SQLFeatureNotSupportedException if the JDBC driver does not support
 106    * this method
 107    * @since 1.4
 108    */
 109   Connection getConnection() throws SQLException;
 110 
 111   /**
 112    * Closes the physical connection that this <code>PooledConnection</code>
 113    * object represents.  An application never calls this method directly;
 114    * it is called by the connection pool module, or manager.
 115    * <P>
 116    * See the {@link PooledConnection interface description} for more
 117    * information.
 118    *
 119    * @exception SQLException if a database access error occurs
 120    * @exception java.sql.SQLFeatureNotSupportedException if the JDBC driver does not support
 121    * this method
 122    * @since 1.4
 123    */
 124   void close() throws SQLException;
 125 
 126   /**
 127    * Registers the given event listener so that it will be notified
 128    * when an event occurs on this <code>PooledConnection</code> object.
 129    *
 130    * @param listener a component, usually the connection pool manager,
 131    *        that has implemented the
 132    *        <code>ConnectionEventListener</code> interface and wants to be
 133    *        notified when the connection is closed or has an error
 134    * @see #removeConnectionEventListener
 135    */
 136   void addConnectionEventListener(ConnectionEventListener listener);
 137 
 138   /**
 139    * Removes the given event listener from the list of components that
 140    * will be notified when an event occurs on this
 141    * <code>PooledConnection</code> object.
 142    *
 143    * @param listener a component, usually the connection pool manager,
 144    *        that has implemented the
 145    *        <code>ConnectionEventListener</code> interface and
 146    *        been registered with this <code>PooledConnection</code> object as
 147    *        a listener
 148    * @see #addConnectionEventListener
 149    */
 150   void removeConnectionEventListener(ConnectionEventListener listener);
 151 
 152         /**
 153          * Registers a <code>StatementEventListener</code> with this <code>PooledConnection</code> object.  Components that
 154          * wish to be notified when  <code>PreparedStatement</code>s created by the
 155          * connection are closed or are detected to be invalid may use this method
 156          * to register a <code>StatementEventListener</code> with this <code>PooledConnection</code> object.
 157          * <p>
 158          * @param listener      an component which implements the <code>StatementEventListener</code>
 159          *                                      interface that is to be registered with this <code>PooledConnection</code> object
 160          * <p>
 161          * @since 1.6
 162          */
 163         public void addStatementEventListener(StatementEventListener listener);
 164 
 165         /**
 166          * Removes the specified <code>StatementEventListener</code> from the list of
 167          * components that will be notified when the driver detects that a
 168          * <code>PreparedStatement</code> has been closed or is invalid.
 169          * <p>
 170          * @param listener      the component which implements the
 171          *                                      <code>StatementEventListener</code> interface that was previously
 172          *                                      registered with this <code>PooledConnection</code> object
 173          * <p>
 174          * @since 1.6
 175          */
 176         public void removeStatementEventListener(StatementEventListener listener);
 177 
 178  }