Connection Pooling with Commons DBCP BasicDataSource

JDBC for MySQL - Herong's Tutorial Examples

∟Connection Pooling with Commons DBCP BasicDataSource

This section provides a tutorial example that shows you how to use the Commons DBCP BasicDataSource class to manage the connection pool with JavaBean style properties.

The easiest way to use Commons DBCP package for connection pooling is to use the org.apache.commons.dbcp2.BasicDataSource class. It implements the standard JDBC javax.sql.DataSource interface to manage the connection pool with JavaBean style properties.

The BasicDataSource class uses set*() and get*() methods to configure and manage the connection pool. Here is my sample Java program, DbcpBasicDataSourceTest.java against my local MySQL server.

/* DbcpBasicDataSourceTest.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import javax.sql.DataSource;
import org.apache.commons.dbcp2.BasicDataSource;

public class DbcpBasicDataSourceTest {
  static java.io.PrintStream out = System.out;

  public static void main(String[] args) throws Exception { 
    String url = "jdbc:mysql://localhost:3306/HerongDB?"
               + "user=Herong&password=TopSecret";

    // Get a DataSource with pooled connections
    DataSource ds = getDataSource(url);

    // Get a pooled connection
    Connection con = ds.getConnection();
    checkDataSource(ds);

    // Verify the pooled connection
    DatabaseMetaData meta = con.getMetaData();
    out.println();
    out.println("Database Connection Info: ");
    out.println("   Server name: "+meta.getDatabaseProductName());
    out.println("   Server version: "+meta.getDatabaseProductVersion());
    out.println("   Driver name: "+ meta.getDriverName());
    out.println("   Driver version: "+ meta.getDriverVersion());
    out.println("   JDBC major version: "+ meta.getJDBCMajorVersion());
    out.println("   JDBC minor version: "+ meta.getJDBCMinorVersion());

    // Close the pooled connection 
    con.close();

    // Wait for 3 minutes to check the server side
    out.println();
    out.println("Go and count connections on the database server ...");
    Thread.sleep(3*60*1000);

    // Close the DataSource
    closeDataSource(ds);
  }

  public static DataSource getDataSource(String url) throws Exception {
    BasicDataSource bds = new BasicDataSource();
    bds.setUrl(url);
    bds.setInitialSize(10);
    DataSource ds = (DataSource) bds;
    return ds;
  }

  public static void closeDataSource(DataSource ds) throws Exception {
    BasicDataSource bds = (BasicDataSource) ds;
    bds.close();
  }

  public static void checkDataSource(DataSource ds) {
    BasicDataSource bds = (BasicDataSource) ds;
    out.println();
    out.println("DBCP BasicDataSource Info: ");
    out.println("   Active Connections: " + bds.getNumActive());
    out.println("   Idle Connections: " + bds.getNumIdle());
    out.println("   Connection URL: " + bds.getUrl());
    out.println("   Driver Class: " + bds.getDriverClassName());
    out.println("   User Name: " + bds.getUsername());
    out.println("   Password: " + bds.getPassword());
  }
}

To run this test program, I need 4 JAR files. See other tutorials to download them.

commons-dbcp2-2.8.0.jar - To provide JDBC connection pooling.
commons-pool2-2.10.0.jar - To provide object pooling API. Required by commons-dbcp2-2.8.0.jar.
commons-logging-1.2.jar - To provide message logging. Required by commons-dbcp2-2.8.0.jar.
mysql-connector-java-8.0.27.jar - To provide JDBC driver for MySQL server.

Let's run it:

herong> java -cp .:\
  commons-dbcp2-2.8.0.jar:\
  commons-pool2-2.10.0.jar:\
  commons-logging-1.2.jar:\
  mysql-connector-java-8.0.27.jar \
  DbcpBasicDataSourceTest.java

DBCP BasicDataSource Info: 
   Active Connections: 1
   Idle Connections: 7
   Connection URL: jdbc:mysql://localhost:3306/HerongDB?user=Herong...
   Driver Class: null
   User Name: null
   Password: null

Database Connection Info: 
   Server name: MySQL
   Server version: 8.0.17
   Driver name: MySQL Connector/J
   Driver version: mysql-connector-java-8.0.19 (Revision: ...)
   JDBC major version: 4
   JDBC minor version: 2

Go and count connections on the database server ...

On the MySQL server, log in as "root". I see 8 connections:

mysql> show processlist;
+----+--------+-----------------+----------+---------+--------+
| Id | User   | Host            | db       | Command | Time   |
+----+--------+-----------------+----------+---------+--------+
| 73 | Herong | localhost:52781 | herongdb | Sleep   |     94 |
| 74 | Herong | localhost:52782 | herongdb | Sleep   |     94 |
| 75 | Herong | localhost:52783 | herongdb | Sleep   |     94 |
| 76 | Herong | localhost:52784 | herongdb | Sleep   |     94 |
| 77 | Herong | localhost:52785 | herongdb | Sleep   |     94 |
| 78 | Herong | localhost:52786 | herongdb | Sleep   |     94 |
| 79 | Herong | localhost:52787 | herongdb | Sleep   |     94 |
| 80 | Herong | localhost:52788 | herongdb | Sleep   |     94 |
+----+--------+-----------------+----------+---------+--------+

So, what we can see from this tutorial:

Commons DBCP BasicDataSource class nicely hides the connection pool in a standard JDBC DataSource object. Once created, it can be used in your application to perform normal JDBC operations.
I asked to initialize 10 connections, but I see only 8 connections on MySQL server. Not sure why.
You can easily change the connection URL to test Commons DBCP for connection pooling with Oracle or SQL Server.