Java8 Date调整时间用法_java里data数据类型时间长短怎么设置-优快云博客

本文链接：https://blog.youkuaiyun.com/bigtree_3721/article/details/119802851

这篇博客介绍了如何使用Java8中的日期时间API进行转换和调整，包括Date到LocalDate、LocalTime、LocalDateTime的转换，以及时间的加减操作。示例代码详细展示了各种常见用法，如日期减一天、时间转换等，是理解Java8日期时间处理的实用指南。

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Java8 Date调整时间用法

Date mydate=new Date();
String mydateStr=mydate.toInstant().atZone(ZoneId.systemDefault())
.toLocalDate().minusDays(1)
.format(DateTimeFormatter.ofPattern("yyyyMMdd"));

下面是几个常用的用法

// 01. java.util.Date --> java.time.LocalDateTime
public 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.LocalDate
public 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.LocalTime
public 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.Date
public 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.Date
public 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.Date
public 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);
}

//另外一个用法
	Calendar cal = Calendar.getInstance();
	cal.setTime(new Date());
	cal.add(Calendar.DAY_OF_MONTH, -1); //include current day
	cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONTH), cal.get(Calendar.DAY_OF_MONTH), 0, 0, 0);
	Date fromDate = cal.getTime();
	cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONTH), cal.get(Calendar.DAY_OF_MONTH), 23, 59, 59);
    Date toDate = cal.getTime();

参考文档

Date常用方法和相互时间调整。见这里的文章