StandardPooledConnection.java :  » Database-JDBC-Connection-Pool » xapool » org » enhydra » jdbc » standard » Java Open Source

/*
 * XAPool: Open Source XA JDBC Pool
 * Copyright (C) 2003 Objectweb.org
 * Initial Developer: Lutris Technologies Inc.
 * Contact: xapool-public@lists.debian-sf.objectweb.org
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 * USA
 */
package org.enhydra.jdbc.standard;

import org.enhydra.jdbc.util.Logger;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.Vector;
import javax.sql.ConnectionEvent;
import javax.sql.ConnectionEventListener;
import javax.sql.PooledConnection;

/**
 * Provides an implementation of javax.sql.PooledConnection which
 * is completely generic (i.e. it relies only on JDBC 1 functionality).
 *
 * This class maintains a physical database connection which is
 * passed to each StandardXAConnectionHandle when it is created. It is the
 * StandardXAConnectionHandle object which the application receives and which
 * it perceives as the java.sql.Connection object.
 *
 * StandardXAConnectionHandle objects pass PreparedStatements back to the
 * StandardPooledConnection so that they can be retained across
 * StandardXAConnectionHandle instantiations.
 */
public class StandardPooledConnection implements PooledConnection {

  protected StandardConnectionPoolDataSource dataSource;
  public Connection con; // the physical database connection
  public StandardConnectionHandle connectionHandle;
  // the last StandardConnectionHandle created
  Vector listeners; // objects listening for events on this connection
  boolean isClosed; // true if this connection has been closed
  public Logger log;

  /**
   * Creates the physical database connection.
   */
  public StandardPooledConnection(
    StandardConnectionPoolDataSource dataSource,
    String user,
    String password)
    throws SQLException {
    this.dataSource = dataSource;
    con = dataSource.getConnection(user, password);
    listeners = new Vector(5, 5);
  }

  /**
   * Creates a new StandardConnectionHandle for use by an application.
   * If there is already a StandardConnectionHandle in use then it is
   * closed (i.e. the application has the connection withdrawn).
   */
  synchronized public Connection getConnection()
    throws java.sql.SQLException {
    if (connectionHandle != null) {
      // if there's already a connection handle
      if (!connectionHandle.isClosed()) { // and it hasn't been closed
        connectionHandle.close(); // close it now
      }
    }
    newConnectionHandle();
    return connectionHandle;
  }

  protected void newConnectionHandle() {
    log.debug("StandardPooledConnection:newConnectionHandle");
    connectionHandle =
      new StandardConnectionHandle(
        this,
        dataSource.getMasterPrepStmtCache(),
        dataSource.getPreparedStmtCacheSize());
  }

  public void close() throws java.sql.SQLException {
    con.close();
    dataSource.getMasterPrepStmtCache().remove(con.toString());
  }

  public void addConnectionEventListener(ConnectionEventListener listener) {
    listeners.addElement(listener);
  }

  public void removeConnectionEventListener(ConnectionEventListener listener) {
    listeners.removeElement(listener);
  }

  /**
   * Notifies all listeners that the StandardConnectionHandle created by this
   * PooledConnection has been closed.
   */
  void closeEvent() {
    ConnectionEvent event = new ConnectionEvent(this);
    // create the event that we'll send
    for (int i = 0; i < listeners.size(); i++) { // for each listener
      Object obj = listeners.elementAt(i); // get next listener
      ConnectionEventListener cel = (ConnectionEventListener) obj;
      //cast to something more useful
      cel.connectionClosed(event); // notify this listener
    }

  }

  /**
   * Invoked when a fatal connection error occurs, 
   * just before an SQLException is thrown to the application
   *
   * This method is automatically called when a fatal error 
   * is detected on the base connection. The base connection 
   * is the actual connection that backs the connection
   * handle provided by the getConnection() method
   */
  public void connectionErrorOccurred(ConnectionEvent event) {
    for (int i = 0; i < listeners.size(); i++) { // for each listener
      Object obj = listeners.elementAt(i); // get next listener
      ConnectionEventListener cel = (ConnectionEventListener) obj;
      //cast to something more useful
      cel.connectionErrorOccurred(event); // notify this listener
      //cel.connectionClosed (event);        // notify this listener
    }
  }

  /**
   * Access method allowing access to the underlying physical connection.
   */
  public Connection getPhysicalConnection() {
    return con;
  }

  public void setLogger(Logger alog) {
    log = alog;
  }
  
  public String toString() {
      try {
    StringBuffer sb = new StringBuffer();
    sb.append("StandardPooledConnection:\n");
    sb.append("     is closed local=<"+this.isClosed + ">\n");
    sb.append("     is closed con=<"+con.isClosed() + ">\n");
    sb.append("     connection =<"+this.con + ">\n");
    
    return sb.toString();
      } catch (Exception e) {
    e.printStackTrace();
    return null;
      }
  }
}