Prentice Hall and Sun Microsystems. Personal use only; do not redistribute.
18.7 Connection Pooling
507
Listing 18.19 ConnectionPool.java (continued)
  public synchronized void free(Connection connection) {
    busyConnections.removeElement(connection);
    availableConnections.addElement(connection);
    // Wake up threads that are waiting for a connection
    notifyAll(); 
  }
    
  public synchronized int totalConnections() {
    return(availableConnections.size() +
           busyConnections.size());
  }
  /** Close all the connections. Use with caution:
   *  be sure no connections are in use before
   *  calling. Note that you are not required to
   *  call this when done with a ConnectionPool, since
   *  connections are guaranteed to be closed when
   *  garbage collected. But this method gives more control
   *  regarding when the connections are closed.
   */
  public synchronized void closeAllConnections() {
    closeConnections(availableConnections);
    availableConnections = new Vector();
    closeConnections(busyConnections);
    busyConnections = new Vector();
  }
  private void closeConnections(Vector connections) {
    try {
      for(int i=0; i
        Connection connection =
          (Connection)connections.elementAt(i);
        if (!connection.isClosed()) {
          connection.close();
        }
      }
    } catch(SQLException sqle) {
      // Ignore errors; garbage collect anyhow
    }
  }
  public synchronized String toString() {
    String info =
      "ConnectionPool(" + url + "," + username + ")" +
      ", available=" + availableConnections.size() +
      ", busy=" + busyConnections.size() +
      ", max=" + maxConnections;
    return(info);
  }
}
Second edition of this book: www.coreservlets.com; Sequel: www.moreservlets.com.
Servlet and JSP training courses by book's author: courses.coreservlets.com.






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