1 /*

     2  * Copyright (c) 2000, 2017, 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  * If the connection pool manager wraps or provides a proxy to the logical

    71  * handle returned from a call to {@code PoolConnection.getConnection}, the pool

    72  * manager must do one of the following when the connection pool manager

    73  * closes or returns the {@code PooledConnection} to the pool in response to

    74  * the application calling {@code Connection.close}:

    75  * <ul>

    76  * <li>call {@code endRequest} on the logical {@code Connection} handle

    77  * <li>call {@code close} on the logical {@code Connection} handle

    78  * </ul>

    79  * <p>

    80  * The physical connection is not closed until the connection pool manager

    81  * calls the <code>PooledConnection</code> method <code>close</code>.

    82  * This method is generally called to have an orderly shutdown of the server or

    83  * if a fatal error has made the connection unusable.

    84  *

    85  * <p>

    86  * A connection pool manager is often also a statement pool manager, maintaining

    87  *  a pool of <code>PreparedStatement</code> objects.

    88  *  When an application closes a prepared statement, it calls the

    89  *  <code>PreparedStatement</code>

    90  * method <code>close</code>. When <code>Statement</code> pooling is being done,

    91  * the pool manager is notified because it has registered itself as

    92  * a <code>StatementEventListener</code> object using the

    93  * <code>ConnectionPool</code> method <code>addStatementEventListener</code>.

    94  *  Thus, when an application closes its  <code>PreparedStatement</code>,

    95  * the underlying prepared statement is recycled rather than being closed.

    96  *

    97  * @since 1.4

    98  */

    99 

   100 public interface PooledConnection {

   101 

   102   /**

   103    * Creates and returns a <code>Connection</code> object that is a handle

   104    * for the physical connection that

   105    * this <code>PooledConnection</code> object represents.

   106    * The connection pool manager calls this method when an application has

   107    * called the method <code>DataSource.getConnection</code> and there are

   108    * no <code>PooledConnection</code> objects available. See the

   109    * {@link PooledConnection interface description} for more information.

   110    *

   111    * @return  a <code>Connection</code> object that is a handle to

   112    *          this <code>PooledConnection</code> object

   113    * @exception SQLException if a database access error occurs

   114    * @exception java.sql.SQLFeatureNotSupportedException if the JDBC driver does not support

   115    * this method

   116    * @since 1.4

   117    */

   118   Connection getConnection() throws SQLException;

   119 

   120   /**

   121    * Closes the physical connection that this <code>PooledConnection</code>

   122    * object represents.  An application never calls this method directly;

   123    * it is called by the connection pool module, or manager.

   124    * <P>

   125    * See the {@link PooledConnection interface description} for more

   126    * information.

   127    *

   128    * @exception SQLException if a database access error occurs

   129    * @exception java.sql.SQLFeatureNotSupportedException if the JDBC driver does not support

   130    * this method

   131    * @since 1.4

   132    */

   133   void close() throws SQLException;

   134 

   135   /**

   136    * Registers the given event listener so that it will be notified

   137    * when an event occurs on this <code>PooledConnection</code> object.

   138    *

   139    * @param listener a component, usually the connection pool manager,

   140    *        that has implemented the

   141    *        <code>ConnectionEventListener</code> interface and wants to be

   142    *        notified when the connection is closed or has an error

   143    * @see #removeConnectionEventListener

   144    */

   145   void addConnectionEventListener(ConnectionEventListener listener);

   146 

   147   /**

   148    * Removes the given event listener from the list of components that

   149    * will be notified when an event occurs on this

   150    * <code>PooledConnection</code> object.

   151    *

   152    * @param listener a component, usually the connection pool manager,

   153    *        that has implemented the

   154    *        <code>ConnectionEventListener</code> interface and

   155    *        been registered with this <code>PooledConnection</code> object as

   156    *        a listener

   157    * @see #addConnectionEventListener

   158    */

   159   void removeConnectionEventListener(ConnectionEventListener listener);

   160 

   161         /**

   162          * Registers a <code>StatementEventListener</code> with this <code>PooledConnection</code> object.  Components that

   163          * wish to be notified when  <code>PreparedStatement</code>s created by the

   164          * connection are closed or are detected to be invalid may use this method

   165          * to register a <code>StatementEventListener</code> with this <code>PooledConnection</code> object.

   166          *

   167          * @param listener      an component which implements the <code>StatementEventListener</code>

   168          *                                      interface that is to be registered with this <code>PooledConnection</code> object

   169          *

   170          * @since 1.6

   171          */

   172         public void addStatementEventListener(StatementEventListener listener);

   173 

   174         /**

   175          * Removes the specified <code>StatementEventListener</code> from the list of

   176          * components that will be notified when the driver detects that a

   177          * <code>PreparedStatement</code> has been closed or is invalid.

   178          *

   179          * @param listener      the component which implements the

   180          *                                      <code>StatementEventListener</code> interface that was previously

   181          *                                      registered with this <code>PooledConnection</code> object

   182          *

   183          * @since 1.6

   184          */

   185         public void removeStatementEventListener(StatementEventListener listener);

   186 

   187  }