LocalDateTime、LocalDate、Date的相互转换

1==LocalDateTime 转 LocalDate：

直接调用 toLocalDate() 方法：

LocalDateTime localDateTime = LocalDateTime.now().toLocalDate();

2==LocalDateTime 转 Date：

LocalDateTime localDateTime = LocalDateTime.now();
//获取系统默认时区
ZoneId zoneId = ZoneId.systemDefault();
//时区的日期和时间
ZonedDateTime zonedDateTime = localDateTime.atZone(zoneId);
//获取时刻
Date date = Date.from(zonedDateTime.toInstant());
System.out.println("格式化前：localDateTime:" + localDateTime + "  Date:" + date);
//格式化LocalDateTime、Date
DateTimeFormatter localDateTimeFormat = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
System.out.println("格式化后：localDateTime:" + localDateTimeFormat.format(localDateTime) + "  Date:" + dateFormat.format(date));

3==LocalDate 转 LocalDateTime:

一般调用 atTime() 方法进行赋值:

LocalDate localDate = LocalDate.now();
LocalDateTime localDateTime1 = localDate.atStartOfDay();
LocalDateTime localDateTime2 = localDate.atTime(8,20,33);
LocalDateTime localDateTime3 = localDate.atTime(LocalTime.now());

4==LocalDate 转 Date:

先调用 atStartOfDay() 方法转 LocalDateTime 再转 Date:

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

5==Date 转 LocalDateTime:

先转 ZonedDateTime 再转 LocalDateTime:

Date date = new Date();
ZoneId zoneId = ZoneId.systemDefault();
LocalDateTime localDateTime = date.toInstant().atZone(zoneId).toLocalDateTime(); 

6==Date 转 LocalDate:

Date date = new Date();
ZoneId zoneId = ZoneId.systemDefault();
LocalDate localDate = date.toInstant().atZone(zoneId).toLocalDate();