public Cliente buscaCliente(String cpf) throws SQLException {
		ResultSet rs;
		st.execute("SELECT * FROM cliente WHERE cpf_cliente = '" + cpf + "'");
		rs = st.getResultSet();
		if (rs.next()) {
			Cliente c = new Cliente();
			c.setCpf(rs.getString(1));
			c.setNome(rs.getString(2));
			return c;
		}
		return null;
	}