Apache DBCP Pooling Driver Example

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 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
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 *      http://www.apache.org/licenses/LICENSE-2.0
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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"
//
publicclass ManualPoolingDriverExample {

publicstaticvoid 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();
        }
    }

publicstaticvoid 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.
//
    }

publicstaticvoid 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());
    }

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