Carregar driver JDBC em tempo de execução

public static void main(String[] args) {
		URL jarUrl = getJarUrl(caminhoDoJar);
		addJarToClassPath(jarUrl);
	}
	
	/**
	 * Método que adiciona o jar com o driver jdbc no classpath da aplicação
	 * @param url a url resolvendo o arquivo jar
	 * @throws Exception caso de algum erro inesperado
	 */
	@SuppressWarnings("unchecked")
	private void addJarToClassPath(URL url) throws Exception{
		URLClassLoader sysloader = (URLClassLoader) ClassLoader
				.getSystemClassLoader(); // pega o class loader do sistema
		Class sysclass = URLClassLoader.class;
		Method method = sysclass.getDeclaredMethod("addURL", PARAMETERS_TYPES);
		method.setAccessible(true);
		method.invoke(sysloader, new Object[] { url });
	}

	/**
	 * Método de fabrica para uma transformar o caminho de um jar em uma url validada
	 * @param jarPath
	 * @return o caminho do jar abstraido em um objeto do tipo URL
	 * @throws MalformedURLException
	 */
	private URL getJarUrl(String jarPath) throws MalformedURLException {
		return new URL("jar", "", "file:" + jarPath + "!/");
	}

package updateclasspath;

public class UpdateClasspath {
    
    public UpdateClasspath() {
    }
    
    private static final Class[] parameters = new Class[]{URL.class};

    public static void addFile(String s) throws IOException {
        File f = new File(s);
        addFile(f);
    }//end method

    public static void addFile(File f) throws IOException {
        addURL(f.toURL());
    }//end method


    public static void addURL(URL u) throws IOException {

        URLClassLoader sysloader = (URLClassLoader)ClassLoader.getSystemClassLoader();
        //URLClassLoader sysloader = (URLClassLoader)Thread.currentThread().getContextClassLoader();
        Class sysclass = URLClassLoader.class;

        try {
                Method method = sysclass.getDeclaredMethod("addURL",parameters);
                method.setAccessible(true);
                method.invoke(sysloader,new Object[]{ u });
        } catch (Throwable t) {
                t.printStackTrace();
                throw new IOException("Error, could not add URL to system classloader");
        }//end try catch

    }//end method

}

private Driver carregarDriverJar(String caminho, String driverClass) {
	try {
		URL caminhoDr = new URL("file",null,"/"+caminho);
		URL[] urls = {caminhoDr};

		URLClassLoader loader = new URLClassLoader(urls);
		Driver driver = (Driver)Class.forName(driverClass,true,loader).newInstance();

		return driver;
	} catch (MalformedURLException ep) {
		ep.printStackTrace();
		return null;
	} catch(ClassNotFoundException ep) {
		ep.printStackTrace();
		return null;
	} catch(IllegalAccessException ep) {
		ep.printStackTrace();
		return null;
	} catch(InstantiationException ep) {
		ep.printStackTrace();
		return null;
	}
}

public void conectar(Driver conDriver, String url, String login, String senha) {
	try {
		DriverManager.registerDriver(new DriverMid(conDriver)); // Atenção para o uso da classe DriverMid
		con = DriverManager.getConnection(url,login,senha);
	} catch(SQLException ep) {
		ep.printStackTrace();
	}
}

import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverPropertyInfo;
import java.sql.SQLException;
import java.util.Properties;

public class DriverMid implements Driver {
	private Driver driver;

	public DriverMid(Driver d) {
		this.driver = d;
	}

	public boolean acceptsURL(String u) throws SQLException {
		return this.driver.acceptsURL(u);
	}

	public Connection connect(String u, Properties p) throws SQLException {
		return this.driver.connect(u, p);
	}

	public int getMajorVersion() {
		return this.driver.getMajorVersion();
	}

	public int getMinorVersion() {
		return this.driver.getMinorVersion();
	}

	public DriverPropertyInfo[] getPropertyInfo(String u, Properties p) throws SQLException {
		return this.driver.getPropertyInfo(u, p);
	}

	public boolean jdbcCompliant() {
		return this.driver.jdbcCompliant();
	}
}