Acesso externo com o mysql

static public Connection getConexao() {
        if (conexao == null) {
            try {

                if (driver == null){
                    //addStringConexao();
                }
                /*Class.forName("com.mysql.jdbc.Driver");
                String url="jdbc:mysql://localhost/dw_apoio_portal";
                String usuario="root";
                String senha="";*/

                String url="jdbc:mysql://192.168.1.150/dw_portal_representante_ricardo";
                String usuario="usuario";
                String senha="1234";

                Class.forName(driver);
                conexao = DriverManager.getConnection(url, usuario, senha);

            } catch (Exception ex) {
                ex.printStackTrace();
                Excecoes excecoes = new Excecoes();
                excecoes.printExceptions(ex.getLocalizedMessage(), "Erro ao tenter se conecat com o banco!");
                excecoes = null;
            }
        }
        return conexao;
    }

java.lang.NullPointerException

at java.lang.Class.forName0(Native Method)

at java.lang.Class.forName(Class.java:169)

at utilitarios.MySQLConnection.getConexao(MySQLConnection.java:48)

at controle.dao.consulta.MySQLServidor.UsuarioDb.obter(UsuarioDb.java:42)

at controle.dao.MySQLServidor.UsuarioDao.obter(UsuarioDao.java:28)

at controle.MySQLServidor.ControleUsuarioMySQLServidor.obter(ControleUsuarioMySQLServidor.java:32)

at views.FrmLoginPortal.btnConectarActionPerformed(FrmLoginPortal.java:112)

at views.FrmLoginPortal.access$100(FrmLoginPortal.java:28)

at views.FrmLoginPortal$2.actionPerformed(FrmLoginPortal.java:73)

at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)

at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)

at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)

at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)

at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)

at java.awt.Component.processMouseEvent(Component.java:6267)

at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)

at java.awt.Component.processEvent(Component.java:6032)

at java.awt.Container.processEvent(Container.java:2041)

at java.awt.Component.dispatchEventImpl(Component.java:4630)

at java.awt.Container.dispatchEventImpl(Container.java:2099)

at java.awt.Component.dispatchEvent(Component.java:4460)

at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4577)

at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4238)

at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)

at java.awt.Container.dispatchEventImpl(Container.java:2085)

at java.awt.Window.dispatchEventImpl(Window.java:2478)

at java.awt.Component.dispatchEvent(Component.java:4460)

at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)

at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)

at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)

at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)

at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)

at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)

at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)