He implementado un ConnectionPool muy simple en Java. No tiene características sofisticadas, solo obtén / libera métodos de conexión.

¿Cómo puedo probar que funciona?

Sé que hay muchas piscinas de conexión listas para usar, que son mucho más confiables que lo que haré, pero solo estoy tratando de practicar para entender cómo funcionan las conexiones Pool.

¡Gracias

Aquí está el código en caso de que ayude:

public class ConnectionPoolImpl implements ConnectionPool {
    private Vector<PooledConnection> connections; // The connections container
    String url;
    String username; 
    String password;

    /**
     * Instanciates a new MySQLConnectionPool
     * @param nbConnectionsMax
     */
    public ConnectionPoolImpl(String DBUrl, String username, String password){
        this.connections = new Vector<PooledConnection>();
        this.url = DBUrl;
        this.username = username;
        this.password = password;
    }

    /**
     * Returns a connection from the pool, if some are available, or create a new one.
     * 
     * @return the connection.
     */
    public Connection getConnection() throws SQLException {
        synchronized(this.connections){
            // Checking if there is an available connection to return
            for(PooledConnection c : this.connections){
                if(!c.isUsed()){
                    c.setUsed();
                    return c.getConnection();
                }
            }

            // If there are none, open a new one and return it
            Connection conn = DriverManager.getConnection(url, username, password);
        PooledConnection pConn = new PooledConnection(conn);
        pConn.setUsed();
        connections.add(pConn);
        return pConn.getConnection();
        }
    }

    /**
     * Releases a connection to the pool.
     * 
     * @param con the connection to release.
     */
    public void releaseConnection(Connection con) throws SQLException {
        synchronized(this.connections){
            for(PooledConnection c : this.connections){
                if(c.getConnection().equals(con)){
                    c.setFree();
                    return;
                }
            }
        }
      }
}

Y mi PooledConnection.java

public class PooledConnection {
    private Connection conn;
    private boolean used;

    public PooledConnection(Connection conn){
        this.conn = conn;
        this.used = false;
    }

    public void setUsed(){
        this.used = true;
    }

    public void setFree(){
        this.used = false;
    }

    public boolean isUsed(){
        return this.used;
    }

    public Connection getConnection(){
        return this.conn;
    }
}