Package javax.sql

Interface PooledConnection

public interface PooledConnection
An interface which provides facilities for handling connections to a database which are pooled.

Typically, a PooledConnection is recycled when it is no longer required by an application, rather than being closed and discarded. The reason for treating connections in this way is that it can be an expensive process both to establish a connection to a database and to destroy the connection. Reusing connections through a pool is a way of improving system performance and reducing overhead.

It is not intended that an application uses the PooledConnection interface directly. The PooledConnection interface is intended for use by a component called a connection pool manager, typically part of the infrastructure that supports use of the database by applications.

Applications obtain connections to the database by calling the DataSource.getConnection() method. Behind the scenes, the connection pool manager will get a PooledConnection object from its connection pool and passes back a connection object that wraps or references the PooledConnection object. A new PooledConnection object will only be created if the pool is empty.

When the application is finished using a PooledConnection, the application calls the Connection.close() method. The connection pool manager is notified via a ConnectionEvent from the connection that this has happened (the pool manager registers itself with the connection before the connection is given to the application). The pool manager removes the underlying PooledConnection object from the connection and returns it to the pool for reuse - the PooledConnection is thus recycled rather than being destroyed.

The connection to the database represented by the PooledConnection is kept open until the PooledConnection object itself is deactivated by the connection pool manager, which calls PooledConnection.close(). This is typically done if there are too many inactive connections in the pool, if the PooledConnection encounters a problem that makes it unusable or if the whole system is being shut down.

  • Method Details

    • addConnectionEventListener

      void addConnectionEventListener​(ConnectionEventListener theListener)
      Registers the supplied ConnectionEventListener with this PooledConnection. Once registered, the ConnectionEventListener will receive ConnectionEvent events when they occur in the PooledConnection.
      Parameters:
      theListener - an object which implements the ConnectionEventListener interface.

    • close

      void close() throws SQLException
      Closes the connection to the database held by this PooledConnection. This method should not be called directly by application code - it is intended only for the connection pool manager component.
      Throws:
      SQLException - if there is a problem accessing the database.

    • getConnection

      Connection getConnection() throws SQLException
      Creates a connection to the database. This method is typically called by the connection pool manager when an application invokes the method DataSource.getConnection() and there are no PooledConnection objects available in the connection pool.
      Returns:
      a Connection object.
      Throws:
      SQLException - if there is a problem accessing the database.

    • removeConnectionEventListener

      void removeConnectionEventListener​(ConnectionEventListener theListener)
      Unregisters the supplied ConnectionEventListener from this PooledConnection. Once unregistered, the ConnectionEventListener will no longer receive events occurring in the PooledConnection.
      Parameters:
      theListener - an object which implements the ConnectionEventListener interface. This object should have previously been registered with the PooledConnection using the addConnectionEventListener method.

    • addStatementEventListener

      void addStatementEventListener​(StatementEventListener listener)
      Add a StatementEventListener to this PooledConnection object.
      Parameters:
      listener - A StatementEventListener object which is to be added with this PooledConnection object
      Since:
      1.6

    • removeStatementEventListener

      void removeStatementEventListener​(StatementEventListener listener)
      Remove a StatementEventListener from this PooledConnection object.
      Parameters:
      listener - A StatementEventListener object which is to be removed form this PooledConnection object
      Since:
      1.6