有些场合要求这样显示
2025-06-05 12:03:11 显示成 2025-6-5 12:3:11

指定format对象的pattern就好

LocalDateTime now = LocalDateTime.now();

DateTimeFormatter formatter1 = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
DateTimeFormatter formatter2 = DateTimeFormatter.ofPattern("yyyy-M-d H:m:s");

System.out.println(now.format(formatter1));
System.out.println(now.format(formatter2));

输出

2025-06-05 09:45:31
2025-6-5 9:45:31

参看java.time.format.DateTimeFormatterBuilder中对格式的注释，SimpleDateFormat也一样