Java - 时间日期类

1.LocalData，LocalTime， LocalDataTime

LocalDate now1 = LocalDate.now();
LocalTime now2 = LocalTime.now();
LocalDateTime now3 = LocalDateTime.now();

now1.toString(); now2.toString(); now3.toString();
2021-11-06
20:17:05.697
2021-11-06T20:17:05.697

常用方法
1.LocalDate
public int getYear(); 年
public int getMonthValue(); 月
public int getDayOfMonth(); 日
public int getDayOfYear(); 当前年的第几天
getDayOfWeek().getValue(); 当前周的第几天

2.LocalTime
public int getHour(); 时
public int getMinute(); 分
public int getSecond(); 秒
public int getNano(); 毫秒

3.LocalDataTime
包含 LocalDate 与 LocalDataTime中的所有方法

2.DateTimeFormatter用法

1.日期转字符串
LocalDate localDate = LocalDate.now();
String format = localDate.format(DateTimeFormatter.ofPattern("yyyy/MM/dd"));

LocalTime localTime = LocalTime.now();
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("hh:mm:ss");
String format = localTime.format(formatter);

LocalDateTime localDateTime = LocalDateTime.now();
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd hh:mm:ss");
String format5 = localDateTime.format(formatter2);

2.字符串转日期
DateTimeFormatter dt = DateTimeFormatter.ofPattern("yyyy/MM/dd");
LocalDate localDate = LocalDate.parse("2021/11/06",dt);

DateTimeFormatter dt = DateTimeFormatter.ofPattern("HH:mm:ss");
LocalTime localDate = LocalTime.parse("21:30:45",dt);

DateTimeFormatter dt = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"); // 24小时
LocalDateTime localDateTime = LocalDateTime.parse("2019-12-07 07:43:53",dt);