//2 jdbc实现代码

    @Test

    public void testJDBC() {

        Connection conn = null;

        PreparedStatement psmt = null;

        ResultSet rs = null;

        //加载驱动

        try{

            Class.forName("com.mysql.jdbc.Driver");

            //创建连接

            conn = DriverManager.getConnection("jdbc:mysql:///spring0702","root","root");

            //编写sql语句

            String sql = "select * from user where username=?";

            //预编译sql

            psmt = conn.prepareStatement(sql);

            //设置属性值

            psmt.setString(1, "jack");

            //执行sql语句

            rs = psmt.executeQuery();

            //遍历结果集

            while(rs.next()) {

                //得到返回结果集

                String username = rs.getString("username");

                String password = rs.getString("password");

                //放到user对象里面

                User user = new User();

                user.setUsername(username);

                user.setPassword(password);

                System.out.println(user);

            }

        }catch (Exception e) {

            e.printStackTrace();

        }finally {

            try {

                rs.close();

                psmt.close();

                conn.close();

            }catch (SQLException e) {

                e.printStackTrace();

            }

        }