DBCP Pooling Driver SnippetHere's a simple example of how to use the PoolingDriver. In this example, we'll construct the PoolingDriver manually, just to show how the pieces fit together, but you could also configure it using an external conifguration file in JOCL format (and eventually Digester).<!>
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import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.SQLException;

//
// Here are the dbcp-specific classes.
// Note that they are only used in the setupDriver
// method. In normal use, your classes interact
// only with the standard JDBC API
//
import org.apache.commons.pool.ObjectPool;
import org.apache.commons.pool.impl.GenericObjectPool;
import org.apache.commons.dbcp.ConnectionFactory;
import org.apache.commons.dbcp.PoolingDriver;
import org.apache.commons.dbcp.PoolableConnectionFactory;
import org.apache.commons.dbcp.DriverManagerConnectionFactory;

//
// To compile this example, you'll want:
// * commons-pool-1.5.4.jar
// * commons-dbcp-1.2.2.jar
// in your classpath.
//
// To run this example, you'll want:
// * commons-collections.jar
// * commons-pool-1.5.4.jar
// * commons-dbcp-1.2.2.jar
// * the classes for your (underlying) JDBC driver
// in your classpath.
//
// Invoke the class using two arguments:
// * the connect string for your underlying JDBC driver
// * the query you'd like to execute
// You'll also want to ensure your underlying JDBC driver
// is registered. You can use the "jdbc.drivers"
// property to do this.
//
// For example:
// java -Djdbc.drivers=oracle.jdbc.driver.OracleDriver
// -classpath commons-pool-1.5.3.jar:commons-dbcp-1.2.2.jar:oracle-jdbc.jar:.
// ManualPoolingDriverExample
// "jdbc:oracle:thin:scott/tiger@myhost:1521:mysid"
// "SELECT * FROM DUAL"
//
public class ManualPoolingDriverExample {

public static void main(String[] args) {
//
// First we load the underlying JDBC driver.
// You need this if you don't use the jdbc.drivers
// system property.
//
System.out.println("Loading underlying JDBC driver.");
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
System.out.println("Done.");

//
// Then we set up and register the PoolingDriver.
// Normally this would be handled auto-magically by
// an external configuration, but in this example we'll
// do it manually.
//
System.out.println("Setting up driver.");
try {
setupDriver(args[0]);
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("Done.");

//
// Now, we can use JDBC as we normally would.
// Using the connect string
// jdbc:apache:commons:dbcp:example
// The general form being:
// jdbc:apache:commons:dbcp:<name-of-pool>
//

Connection conn = null;
Statement stmt = null;
ResultSet rset = null;

try {
System.out.println("Creating connection.");
conn = DriverManager.getConnection("jdbc:apache:commons:dbcp:example");
System.out.println("Creating statement.");
stmt = conn.createStatement();
System.out.println("Executing statement.");
rset = stmt.executeQuery(args[1]);
System.out.println("Results:");
int numcols = rset.getMetaData().getColumnCount();
while(rset.next()) {
for(int i=1;i<=numcols;i++) {
System.out.print("t" + rset.getString(i));
}
System.out.println("");
}
} catch(SQLException e) {
e.printStackTrace();
} finally {
try { if (rset != null) rset.close(); } catch(Exception e) { }
try { if (stmt != null) stmt.close(); } catch(Exception e) { }
try { if (conn != null) conn.close(); } catch(Exception e) { }
}

// Display some pool statistics
try {
printDriverStats();
} catch (Exception e) {
e.printStackTrace();
}

// closes the pool
try {
shutdownDriver();
} catch (Exception e) {
e.printStackTrace();
}
}

public static void setupDriver(String connectURI) throws Exception {
//
// First, we'll need a ObjectPool that serves as the
// actual pool of connections.
//
// We'll use a GenericObjectPool instance, although
// any ObjectPool implementation will suffice.
//
ObjectPool connectionPool = new GenericObjectPool(null);

//
// Next, we'll create a ConnectionFactory that the
// pool will use to create Connections.
// We'll use the DriverManagerConnectionFactory,
// using the connect string passed in the command line
// arguments.
//
ConnectionFactory connectionFactory = new DriverManagerConnectionFactory(connectURI,null);

//
// Now we'll create the PoolableConnectionFactory, which wraps
// the "real" Connections created by the ConnectionFactory with
// the classes that implement the pooling functionality.
//
PoolableConnectionFactory poolableConnectionFactory = new PoolableConnectionFactory(connectionFactory,connectionPool,null,null,false,true);

//
// Finally, we create the PoolingDriver itself...
//
Class.forName("org.apache.commons.dbcp.PoolingDriver");
PoolingDriver driver = (PoolingDriver) DriverManager.getDriver("jdbc:apache:commons:dbcp:");

//
// ...and register our pool with it.
//
driver.registerPool("example",connectionPool);

//
// Now we can just use the connect string "jdbc:apache:commons:dbcp:example"
// to access our pool of Connections.
//
}

public static void printDriverStats() throws Exception {
PoolingDriver driver = (PoolingDriver) DriverManager.getDriver("jdbc:apache:commons:dbcp:");
ObjectPool connectionPool = driver.getConnectionPool("example");

System.out.println("NumActive: " + connectionPool.getNumActive());
System.out.println("NumIdle: " + connectionPool.getNumIdle());
}

public static void shutdownDriver() throws Exception {
PoolingDriver driver = (PoolingDriver) DriverManager.getDriver("jdbc:apache:commons:dbcp:");
driver.closePool("example");
}
}