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ConnectionPool.javaAPI DocExample2606Tue Jan 25 10:45:14 GMT 2000None

ConnectionPool

public class ConnectionPool extends Object

Fields Summary
private Hashtable
connections
private int
increment
private String
dbURL
private String
user
private String
password
Constructors Summary
public ConnectionPool(String dbURL, String user, String password, String driverClassName, int initialConnections, int increment)

 
    // Load the specified driver class
    Class.forName(driverClassName);

    this.dbURL = dbURL;
    this.user = user;
    this.password = password;
    this.increment = increment;

    connections = new Hashtable();
 
    // Put our pool of Connections in the Hashtable
    // The FALSE value indicates they're unused
    for(int i = 0; i < initialConnections; i++) {
      connections.put(DriverManager.getConnection(dbURL, user, password),
                      Boolean.FALSE);
    }
Methods Summary
public java.sql.ConnectiongetConnection()

    Connection con = null;

    Enumeration cons = connections.keys();

    synchronized (connections) {
      while(cons.hasMoreElements()) {
        con = (Connection)cons.nextElement();

        Boolean b = (Boolean)connections.get(con);
        if (b == Boolean.FALSE) {
          // So we found an unused connection.
          // Test its integrity with a quick setAutoCommit(true) call.
          // For production use, more testing should be performed,
          // such as executing a simple query.
          try {
            con.setAutoCommit(true);
          }
          catch(SQLException e) {
            // Problem with the connection, replace it.
            con = DriverManager.getConnection(dbURL, user, password);
          }
          // Update the Hashtable to show this one's taken
          connections.put(con, Boolean.TRUE);
          // Return the connection
          return con;
        }
      }
    }
  
    // If we get here, there were no free connections.
    // We've got to make more.
    for(int i = 0; i < increment; i++) {
      connections.put(DriverManager.getConnection(dbURL, user, password),
                      Boolean.FALSE); 
    }	
 
    // Recurse to get one of the new connections.
    return getConnection();
public voidreturnConnection(java.sql.Connection returned)

    Connection con;
    Enumeration cons = connections.keys();
    while (cons.hasMoreElements()) {
      con = (Connection)cons.nextElement();
      if (con == returned) {
        connections.put(con, Boolean.FALSE);
        break;
      }
    }