public static EntityManager getEntityManager()
{

    Map properties = new HashMap();

    properties.put("javax.persistence.jdbc.driver", "com.mysql.jdbc.Driver");
    properties.put("javax.persistence.jdbc.drivejavax.persistence.jdbc.url", "jdbc:mysql://localhost:3306/g_vendas");
    properties.put("javax.persistence.jdbc.driver", "com.mysql.jdbc.Driver");
    properties.put("javax.persistence.jdbc.password", "root");
    properties.put("javax.persistence.jdbc.user", "root");


    return emf.createEntityManager();
}