@Test
    public void testQuery() throws ClassNotFoundException, SQLException {
        //加载驱动
       Class.forName("oracle.jdbc.driver.OracleDriver");
       //获得连接
        Connection connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "o_user1", "p123456");
        //准备sql语句
        String sql = "select * from emp where empno = ?";
        //获取执行sql语句的对象
        PreparedStatement pstm = connection.prepareStatement(sql);
        pstm.setInt(1, 7788);
        //执行sql语句
        ResultSet resultSet = pstm.executeQuery();
        //处理结果集
        while (resultSet.next()) {
            System.out.println(resultSet.getString("ename"));
        }
        //释放资源
        resultSet.close();
        pstm.close();
        connection.close();
    }