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),
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 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.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.
connections.remove(con);
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 void | returnConnection(java.sql.Connection returned)
if (connections.containsKey(returned)) {
connections.put(returned, Boolean.FALSE);
}
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