Timestamp、LocalDateTime、DateTime、String、LocalDate、Date轉換

1.Timestamp轉LocalDateTime（mysql中datetime數據取出時是timestamp類型）

LocalDateTime localDateTime = new Timestamp(System.currentTimeMillis()).toLocalDateTime(); 
//或者 
LocalDateTime localDateTime1 = LocalDateTime.ofInstant(new Timestamp(System.currentTimeMillis()).toInstant(),ZoneId.systemDefault());

注意轉換以後會有字符T存在

String str = localDateTime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));//去掉T和毫秒值

2.LocalDateTime轉Timestamp

Timestamp timestamp = Timestamp.valueOf(LocalDateTime.now());

3.Date轉LocalDate

LocalDate localDate = LocalDate.ofInstant(new Date().toInstant(), ZoneId.systemDefault()); 
//或者 
LocalDate localDate1 = new Date().toInstant().atZone(ZoneId.systemDefault()).toLocalDate();

4.LocalDate轉Date

Date date = Date.from(LocalDate.now().atStartOfDay().atZone(ZoneId.systemDefault()).toInstant());

5.Date轉LocalDateTime

LocalDateTime localDateTime = LocalDateTime.ofInstant(new Date().toInstant(),ZoneId.systemDefault());
//或者
LocalDateTime localDateTime1 = new Date().toInstant().atZone(ZoneId.systemDefault()).toLocalDateTime();

6.LocalDateTime轉LocalDate

LocalDate localDate = LocalDateTime.now().toLocalDate();

7.LocalDate轉LocalDateTime

LocalDateTime localDateTime = LocalDate.now().atStartOfDay().atZone(ZoneId.systemDefault()).toLocalDateTime();

8.LocalDateTime轉Date

Date date = Date.from(LocalDateTime.now().atZone(ZoneId.systemDefault()).toInstant());

9.String轉LocalDate

LocalDate localDate = LocalDate.parse("2018-09-15", DateTimeFormatter.ofPattern("yyyy-MM-dd"));

注意String中是‘-’鏈接則解析方法也必須是‘-’鏈接，不然解析不了

10.String轉LocalDateTime

LocalDateTime localDateTime1 = LocalDateTime.parse("2019-05-20 15:33:24",DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));

注意String中是‘-’ 和‘:’鏈接則解析方法也必須是‘-’和':'鏈接，不然解析不了