SQLConnectionPool.java

package utils;

import org.apache.commons.dbcp2.*;
import org.apache.commons.pool2.impl.GenericObjectPool;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

public class SQLConnectionPool {
    private static String driver = "com.mysql.cj.jdbc.Driver";
    private static String connectionUrl = "jdbc:mysql://" +
            Configuration.getInstance().getConfig("MYSQL_HOST") + ":" +
            Configuration.getInstance().getConfig("MYSQL_PORT") + "/" +
            Configuration.getInstance().getConfig("MYSQL_DB") +
            "?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&interactiveClient=true&useSSL=false";
    private DataSource dataSource;

    public SQLConnectionPool() {
        try {
            Class.forName(driver);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        //
        // First, 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(connectionUrl,
                Configuration.getInstance().getConfig("MYSQL_USER"),
                Configuration.getInstance().getConfig("MYSQL_PASS"));
        //
        // Next 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,
                null
        );

        //
        // Now 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.
        //
        GenericObjectPool<PoolableConnection> connectionPool = new GenericObjectPool<>(poolableConnectionFactory);

        // Set the factory's pool property to the owning pool
        poolableConnectionFactory.setPool(connectionPool);

        //
        // Finally, we create the PoolingDriver itself,
        // passing in the object pool we created.
        //
        this.dataSource = new PoolingDataSource<>(connectionPool);
    }

    public Connection getConnection() throws SQLException {
        //
        // Get connection from pool
        // When done, use Connection.close() to return it to pool
        //
        return this.dataSource.getConnection();
    }
}