LocalDate、LocalDateTime与timestamp、Date的转换

1.LocalDate转Date

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

2.LocalDateTime转Date

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

3.Date转LocalDateTime(LocalDate)

Date date = new Date();
LocalDateTime localDateTime = date.toInstant().atZone(ZoneId.systemDefault()).toLocalDateTime();
LocalDate localDate = date.toInstant().atZone(ZoneId.systemDefault()).toLocalDate();

4.LocalDate转时间戳

LocalDate localDate = LocalDate.now();
long timestamp = localDate.atStartOfDay(ZoneId.systemDefault()).toInstant().toEpochMilli();

5.LocalDateTime转时间戳

LocalDateTime localDateTime = LocalDateTime.now();
long timestamp = localDateTime.toInstant(ZoneOffset.ofHours(8)).toEpochMilli();

//获取秒数
Long second = LocalDateTime.now().toEpochSecond(ZoneOffset.of("+8"));
//获取毫秒数
Long milliSecond = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).toEpochMilli();

6.时间戳转LocalDateTime(LocalDate)

long timestamp = System.currentTimeMillis();
LocalDate localDate = Instant.ofEpochMilli(timestamp).atZone(ZoneId.systemDefault()).toLocalDate();
LocalDateTime localDateTime = Instant.ofEpochMilli(timestamp).atZone(ZoneId.systemDefault()).toLocalDateTime();

7.LocalDateTime与String互转

//时间转字符串格式化
 DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMddHHmmssSSS");
 String dateTime = LocalDateTime.now(ZoneOffset.of("+8")).format(formatter);
 
//字符串转时间
String dateTimeStr = "2018-07-28 14:11:15";
DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
LocalDateTime dateTime = LocalDateTime.parse(dateTimeStr, df);

8.LocalDate计算相隔天数

   // 开始日期
LocalDate startDate = LocalDate.parse("2020-05-08");
// 结束日期
LocalDate endDate = LocalDate.parse("2020-06-09");
// 剩余天数
int lastDayInt = (int) (endDate.toEpochDay() - startDate.toEpochDay());

另外可以使用DAYS.between(day0, day1)就可以计算出相应的天数。
9.获取月初与月末

//获取月初
 LocalDate monthOfFirstDate=LocalDate.parse(count_date,
                DateTimeFormatter.ofPattern("yyyy-MM-dd")).with(TemporalAdjusters.firstDayOfMonth());
//获取月末
 LocalDate monthOfLastDate=LocalDate.parse(count_date,
                DateTimeFormatter.ofPattern("yyyy-MM-dd")).with(TemporalAdjusters.lastDayOfMonth())