使用PreparedStatement查询数据库表中所有元素

public class JDBCDemo04 {
    @Test
    public void queryAll() throws SQLException {
        Connection con = JDBCUtil.getConnect();

        String sql = "select * from users";
        PreparedStatement pstmt = con.prepareStatement(sql);

        List<User> list = new ArrayList<>();
        ResultSet rs = pstmt.executeQuery();
        while (rs.next()){
            String uid = rs.getString("uid");
            String uname = rs.getString("uname");
            String upass = rs.getString("upass");
            User user = new User(uid,uname,upass);
            list.add(user);
        }
        if (list.size()==0){
            System.out.println("没有查询到结果");
        }else {
            for (User u : list) {
                System.out.println(u);
            }
        }
        JDBCUtil.release(con,pstmt,rs);
    }
}