JAVA8 常用的日期时间方法

JAVA8 更新了原本线程不安全的SimpleDateFormat, 新的DateTimeFormatter则是线程安全的。

下面列出JAVA8开发中常用的时间操作。

import java.time.DayOfWeek;
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.Month;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoField;

public class TimeTest {
    public static void main(String[] args) {
        // 获取当前年月日 - 2019-11-06
        LocalDate nowDate = LocalDate.now();
        // 2019
        int nowYear = nowDate.getYear();
        // 2019
        int nowYear1 = nowDate.get(ChronoField.YEAR);
        // NOVEMBER
        Month nowMonth = nowDate.getMonth();
        // 11
        int nowMonth1 = nowDate.get(ChronoField.MONTH_OF_YEAR);
        // 6
        int nowDay = nowDate.getDayOfMonth();
        // 6
        int nowDay1 = nowDate.get(ChronoField.DAY_OF_MONTH);
        // WEDNESDAY
        DayOfWeek dayOfWeek = nowDate.getDayOfWeek();
        // 3
        int dayOfWeek1 = nowDate.get(ChronoField.DAY_OF_WEEK);
        // 获取当前时分秒 - 15:16:24.401
        LocalTime nowTime = LocalTime.now();
        // 指定时分秒 - 12:51:10
        LocalTime nowTime1 = LocalTime.of(12, 51, 10);
        // 指定时间 - 2019-11-06
        LocalDate specificTime = LocalDate.of(2019, 11, 6);
        
        // LocalDateTime 获取年月日时分秒
        LocalDateTime localDateTime = LocalDateTime.now();
        // 指定时间 2019-11-11T16:14:20
        LocalDateTime localDateTime1 = LocalDateTime.of(2019, Month.NOVEMBER, 11, 16, 14, 20);
        // 2019-11-06T16:19:51.506
        LocalDateTime localDateTime2 = LocalDateTime.of(nowDate, nowTime);
        // LocalDateTime localDateTime3 = LocalDat

        // 获取毫秒数
        // 获取当前时间 2019-11-06T07:18:39.956Z
        Instant instant = Instant.now();
        // 1573028684 得到的是秒数
        long currentSecond = instant.getEpochSecond();
        // 1573028779924 得到毫秒数
        long currentMilli = instant.toEpochMilli();
        // 获取当前年月日 - 2019-11-06
        LocalDate date = Instant.ofEpochMilli(instant.toEpochMilli()).atZone(ZoneId.systemDefault()).toLocalDate();

        // 格式化时间
        // 2019-11-06
        LocalDate localDate = LocalDate.of(2019, 11, 6);
        // 20191106
        String str1 = localDate.format(DateTimeFormatter.BASIC_ISO_DATE);
        // 2019-11-06
        String str2 = localDate.format(DateTimeFormatter.ISO_LOCAL_DATE);
        // 自定义格式化
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        // 2019-11-06 16:41:10
        String str3 = localDateTime.format(dateTimeFormatter);
        System.out.println(str3);
    }
}