java 8 新特性 时间api使用实例

摘要: 时间api重构是 java8中重大改动

java 8 提供的 时间api java.time 比原来的Calendar 方便很多。主要提供了
日期类：LocalDate
时间类：LocateDateTime
时间戳操作类：Instant
时间持续时间计算：Duration
时区：ZoneId
日期间隔：Period
java 8 api 是整合了原第三方工具(org.joda.time)，使用将会更加方便。

以下实例针对，日常使用的时间计算方式，进行实例验证。可以根据自己需要提取，时间工具类。
以下是具体的使用实例，建议大家都转换新的时间方式，虽然中间可能要花费些时间，但个人感觉还是值得。

public static void main(String[] args) {
Instant first = Instant.now();
// Current Time
LocalTime time = LocalTime.now();
System.out.println("Current Time=" + time);
// Creating LocalTime by providing input arguments
LocalTime specificTime = LocalTime.of(12, 20, 25, 40);
System.out.println("Specific Time of Day=" + specificTime);
// Try creating time by providing invalid inputs
// Current date in "Asia/Kolkata", you can get it from ZoneId javadoc
LocalTime timeKolkata = LocalTime.now(ZoneId.of("Asia/Kolkata"));
System.out.println("Current Time in IST=" + timeKolkata);

// Getting date from the base date i.e 01/01/1970
LocalTime specificSecondTime = LocalTime.ofSecondOfDay(10000);
System.out.println("10000th second time= " + specificSecondTime);
// 今日
LocalDate localDate = LocalDate.now();
System.out.println("今日日期:" + localDate);
// Create
LocalDate firstDay_2017 = LocalDate.of(2017, Month.JANUARY, 1);
System.out.println("Specific Date=" + firstDay_2017);
LocalDate hundredDay2017 = LocalDate.ofYearDay(2017, 200);
System.out.println("200th day of 2017=" + hundredDay2017);
// plus and minus operations
System.out.println("昨天日期: " + localDate.minusDays(1));
System.out.println("明天日期: " + localDate.plusDays(1));
System.out.println("上月的今天：" + localDate.minusMonths(1));
System.out.println("下个月的今天:" + localDate.plusMonths(1));
// Temporal adjusters for adjusting the dates
System.out.println("本月第1天的日期: " + localDate.with(TemporalAdjusters.firstDayOfMonth()));
System.out.println("本月最后1天的日期: " + localDate.with(TemporalAdjusters.lastDayOfMonth()));
System.out.println("本年最后1天的日期: " + localDate.with(TemporalAdjusters.lastDayOfYear()));
// TemporalFieldfor adjusting the dates
System.out.println("今天是：" + localDate.getYear() + "第" + localDate.get(ChronoField.ALIGNED_WEEK_OF_YEAR) + "周");
System.out.println("今天是周: " + localDate.getDayOfWeek());
System.out.println("今天是本周的第:" + localDate.getDayOfWeek().getValue() + "天");
// before
System.out.println("今天在20171001日之前：" + localDate.isBefore(LocalDate.of(2017, 10, 1)));
// 格式化
System.out.println("格式化：" + localDate.format(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
// Instant 时间戳转换
System.out.println("当前时间:" + Instant.now().atZone(ZoneId.systemDefault()));
System.out.println("当前的时间戳：" + Instant.now().toEpochMilli());
System.out.println(
"时间戳转为时间字符串：" + Instant.ofEpochMilli(Instant.now().toEpochMilli()).atZone(ZoneId.systemDefault()));
// Locale date time
// Current Date
LocalDateTime today = LocalDateTime.now();
System.out.println("Current DateTime=" + today);

// Current Date using LocalDate and LocalTime
today = LocalDateTime.of(LocalDate.now(), LocalTime.now());
System.out.println("Current DateTime=" + today);

// Creating LocalDateTime by providing input arguments
LocalDateTime specificDate = LocalDateTime.of(2014, Month.JANUARY, 1, 10, 10, 30);
System.out.println("Specific Date=" + specificDate);

// Current date in "Asia/Kolkata", you can get it from ZoneId javadoc
LocalDateTime todayKolkata = LocalDateTime.now(ZoneId.of("Asia/Kolkata"));
System.out.println("Current Date in IST=" + todayKolkata);

// Getting date from the base date i.e 01/01/1970
LocalDateTime dateFromBase = LocalDateTime.ofEpochSecond(10000, 0, ZoneOffset.UTC);
System.out.println("10000th second time from 01/01/1970= " + dateFromBase);

// Duration example
Duration thirtyDay = Duration.ofDays(30);
System.out.println("30天" + thirtyDay);

// wait some time while something happens
Instant second = Instant.now();
// 计算两个时间，之间的长度 持续运行时间
Duration duration = Duration.between(first, second);
System.out.println("程序运行时间：" + duration);
// 日期间隔计算
Period period = localDate.until(localDate.with(TemporalAdjusters.lastDayOfYear()));
System.out.println("Period Format= " + period);
System.out.println("Months remaining in the year= " + period.getMonths());
}