Java 8 中 Date与LocalDateTime、LocalDate、LocalTime互转

Java 8中 java.util.Date 类新增了两个方法，分别是from(Instant instant)和toInstant()方法// Obtains an instance of Date from an Instant object.public static Date from(Instant instant) { try { return new Date(instant.toEpochMilli()); } catch (ArithmeticException ex) { throw new IllegalArgumentException(ex); }}// Converts this Date object to an Instant.public Instant toInstant() { return Instant.ofEpochMilli(getTime());} 这两个方法使我们可以方便的实现将旧的日期类转换为新的日期类，具体思路都是通过Instant当中介，然后通过Instant来创建LocalDateTime（这个类可以很容易获取LocalDate和LocalTime），新的日期类转旧的也是如此，将新的先转成LocalDateTime，然后获取Instant，接着转成Date，具体实现细节如下：// 01. java.util.Date --> java.time.LocalDateTimepublic void UDateToLocalDateTime() { java.util.Date date = new java.util.Date(); Instant instant = date.toInstant(); ZoneId zone = ZoneId.systemDefault(); LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, zone);}// 02. java.util.Date --> java.time.LocalDatepublic void UDateToLocalDate() { java.util.Date date = new java.util.Date(); Instant instant = date.toInstant(); ZoneId zone = ZoneId.systemDefault(); LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, zone); LocalDate localDate = localDateTime.toLocalDate();}// 03. java.util.Date --> java.time.LocalTimepublic void UDateToLocalTime() { java.util.Date date = new java.util.Date(); Instant instant = date.toInstant(); ZoneId zone = ZoneId.systemDefault(); LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, zone); LocalTime localTime = localDateTime.toLocalTime();}// 04. java.time.LocalDateTime --> java.util.Datepublic void LocalDateTimeToUdate() { LocalDateTime localDateTime = LocalDateTime.now(); ZoneId zone = ZoneId.systemDefault(); Instant instant = localDateTime.atZone(zone).toInstant(); java.util.Date date = Date.from(instant);}// 05. java.time.LocalDate --> java.util.Datepublic void LocalDateToUdate() { LocalDate localDate = LocalDate.now(); ZoneId zone = ZoneId.systemDefault(); Instant instant = localDate.atStartOfDay().atZone(zone).toInstant(); java.util.Date date = Date.from(instant);}// 06. java.time.LocalTime --> java.util.Datepublic void LocalTimeToUdate() { LocalTime localTime = LocalTime.now(); LocalDate localDate = LocalDate.now(); LocalDateTime localDateTime = LocalDateTime.of(localDate, localTime); ZoneId zone = ZoneId.systemDefault(); Instant instant = localDateTime.atZone(zone).toInstant(); java.util.Date date = Date.from(instant);}