ConnectionPoolpublic class ConnectionPool extends Object | This class implements a connection pool. It's the same as the
ConnectionPool class described in Java Servlet Programming (O'Reilly),
Second Edition, copied with permission from Jason Hunter.
It's used by the DataSourceWrapper class to provide a JDBC 2.0
DataSource interface to the pool. |
| Fields Summary |
|---|
| private Hashtable | connections | | private Properties | props |
| Constructors Summary |
|---|
public ConnectionPool(Properties props, int initialConnections)
this.props = props;
initializePool(props, initialConnections);
| public ConnectionPool(String driverClassName, String dbURL, String user, String password, int initialConnections)
props = new Properties();
props.put("connection.driver", driverClassName);
props.put("connection.url", dbURL);
if (user != null) {
props.put("user", user);
}
if (password != null) {
props.put("password", password);
}
initializePool(props, initialConnections);
|
| Methods Summary |
|---|
| public java.sql.Connection | getConnection()
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.
// First close the connection to be replaced to avoid leaks
try { con.close(); } catch (SQLException ignored) { }
connections.remove(con);
con = getNewConnection();
}
// 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. Make one more.
// A more robust connection pool would have a maximum size limit,
// and would reclaim connections after some timeout period
con = getNewConnection();
connections.put(con, Boolean.FALSE);
return con;
}
| | private java.sql.Connection | getNewConnection()
return DriverManager.getConnection(
props.getProperty("connection.url"), props);
| | private void | initializePool(java.util.Properties props, int initialConnections)
// Load the driver
Class.forName(props.getProperty("connection.driver"));
// Put our pool of Connections in the Hashtable
// The FALSE value indicates they're unused
for(int i = 0; i < initialConnections; i++) {
Connection con = getNewConnection();
connections.put(con, Boolean.FALSE);
}
| | public void | returnConnection(java.sql.Connection returned)
if (connections.containsKey(returned)) {
connections.put(returned, Boolean.FALSE);
}
|
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