Java WEB: Classe Conexão

package br.com.rosanelliweb.classes;

import java.sql.*;

public class Conexao {

private static String _connectionString;

private static Connection _conexao;

public static void Conectar() throws SQLException, ClassNotFoundException {

Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");

_connectionString = "jdbc:sqlserver://localhost:1433;databaseName=Login;user=sa;password=sqlsdk8;";

_conexao = DriverManager.getConnection(_connectionString);
}

public static ResultSet executaconsulta(String query) throws SQLException {
Statement st = _conexao.createStatement();

ResultSet resultado = st.executeQuery(query);

return resultado;
}

public static void executaUpdate(String query) throws SQLException {
Statement st = _conexao.createStatement();

st.executeUpdate(query);
}

public static void fechaConexao() throws SQLException {

_conexao.close();
}

}