字符串时间yyyyMMddHHmmss转成yyyy-MM-dd HH-mm-ss字符串格式

String today= "20210101091240"。bai

String reg = "(\\d{4})(\\d{2})(\\d{2})(\\d{2})(\\d{2})(\\d{2})"。

Stirng date = today.replaceAll(reg, "$1-$2-$3 $4:$5:$6") = "2021-01-01 09:12:40"。