org.mycore.backend.sql
Class MCRSQLConnectionPool

java.lang.Object
  org.mycore.backend.sql.MCRSQLConnectionPool

public class MCRSQLConnectionPool
extends Object

This class implements a pool of database connections to a relational database like DB2, using JDBC. Other classes get a connection from the pool when they need one and release the connection after their work has finished.

Version:

$Revision: 13253 $ $Date: 2008-03-07 09:05:51 +0100 $

Author:

Frank Lützenkirchen, Jens Kupferschmidt

See Also:

MCRSQLConnection

Field Summary

protected Vector<MCRSQLConnection>	freeConnections The internal list of free connections
(package private) static long	maxAge The maximum age a connection can be before it is reconnected
protected int	maxNumConnections The maximum number of connections that will be built
(package private) static int	maxUsages The maximum number of usages of this connection *
(package private) static String	password
protected static MCRSQLConnectionPool	singleton The connection pool singleton
(package private) static String	url
protected Vector<MCRSQLConnection>	usedConnections The internal list of connections that are currently in use
(package private) static String	userID

Constructor Summary

protected

MCRSQLConnectionPool() Builds the connection pool singleton.

Method Summary

void	finalize() Finalizer, closes all connections in this connection pool
MCRSQLConnection	getConnection() Gets a free connection from the pool.
static MCRSQLConnectionPool	instance() Returns the connection pool singleton.
(package private) void	releaseConnection(MCRSQLConnection connection) Releases a connection, indicating that it is not used any more and should be returned to to pool of free connections.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

singleton

protected static MCRSQLConnectionPool singleton

The connection pool singleton

freeConnections

protected Vector<MCRSQLConnection> freeConnections

The internal list of free connections

usedConnections

protected Vector<MCRSQLConnection> usedConnections

The internal list of connections that are currently in use

maxNumConnections

protected int maxNumConnections

The maximum number of connections that will be built

maxUsages

static int maxUsages

The maximum number of usages of this connection *

maxAge

static long maxAge

The maximum age a connection can be before it is reconnected

url

static String url

userID

static String userID

password

static String password

Constructor Detail

MCRSQLConnectionPool

protected MCRSQLConnectionPool()
                        throws MCRPersistenceException

Builds the connection pool singleton.

Throws:

MCRPersistenceException - if the JDBC driver could not be loaded

Method Detail

instance

public static MCRSQLConnectionPool instance()
                                     throws MCRPersistenceException

Returns the connection pool singleton.

Throws:

MCRPersistenceException - if the JDBC driver could not be loaded or initial connections could not be created

getConnection

public MCRSQLConnection getConnection()
                               throws MCRPersistenceException

Gets a free connection from the pool. When this connection is not used any more by the invoker, he is responsible for returning it into the pool by invoking the release() method of the connection.

Returns:

a free connection for your personal use

Throws:

MCRPersistenceException - if there was a problem while building the connection

See Also:

MCRSQLConnection.release()

releaseConnection

void releaseConnection(MCRSQLConnection connection)

Releases a connection, indicating that it is not used any more and should be returned to to pool of free connections. This method is invoked when you call the method release() of the MCRSQLConnection object.

Parameters:

connection - the connection that has been used

See Also:

MCRSQLConnection.release()

finalize

public void finalize()

Finalizer, closes all connections in this connection pool

Overrides:

finalize in class Object