LocalDate和LocalDateTime使用

代码如下

package com.wl.date;

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;

/**
 * @author 没有梦想的java菜鸟
 * @Date 创建时间：2022/10/10 下午3:22
 * @qq 2315290571
 * @Description
 */
public class LocalDateTest {


    public static void main(String[] args) {
        // 1. 获取当前日期时间
        LocalDate nowDate = LocalDate.now();
        System.out.println("当前时间:" + nowDate);

        System.out.println("====================我是分隔符================");
        // 2.格式化日期时间
        DateTimeFormatter pattern1 = DateTimeFormatter.ofPattern("yyyy/MM/dd");
        String strDate = "2022/01/09";
        String format = LocalDate.parse(strDate, pattern1).format(pattern1);
        System.out.println(format);


        System.out.println("====================我是分隔符================");
        // 3.计算日期相差天数
        DateTimeFormatter pattern2 = DateTimeFormatter.ofPattern("yyyy-MM-dd");
        String beginDateStr = "2022-01-01";
        String endDateStr = "2022-01-22";

        LocalDate beginDate = LocalDate.parse(beginDateStr, pattern2);
        LocalDate endDate = LocalDate.parse(endDateStr, pattern2);

        long beginDay = LocalDate.of(beginDate.getYear(), beginDate.getMonth(), beginDate.getDayOfMonth()).toEpochDay();
        long endDay = LocalDate.of(endDate.getYear(), endDate.getMonth(), endDate.getDayOfMonth()).toEpochDay();
        System.out.println("日期相差天数：" + (endDay - beginDay));

        System.out.println("====================我是分隔符================");

        // 4.获取当前时间
        LocalDateTime nowTime = LocalDateTime.now();
        // 北京时间当前时间秒值
        long nowSecond = nowTime.toEpochSecond(ZoneOffset.of("+8"));
        // 毫秒值
        long nowMilliSecond = nowTime.toInstant(ZoneOffset.of("+8")).toEpochMilli();
        System.out.println(nowTime);
        System.out.println(nowSecond);
        System.out.println(nowMilliSecond);
        System.out.println("====================我是分隔符================");
        // 5.String和LocalDateTime 互转

        // 当前时间格式化
        DateTimeFormatter pattern3 = DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss.SSS");
        String dateTime = LocalDateTime.now(ZoneId.of("+8")).format(pattern3);
        System.out.println(dateTime);

        // 字符串转时间
        String dateTimeStr="2022-07-28 14:11:15";
        DateTimeFormatter pattern4 = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        LocalDateTime time = LocalDateTime.parse(dateTimeStr, pattern4);
        System.out.println(time);
        // 将时区时间转换成 北京时间
        ZonedDateTime shanghaiDateTime =  ZonedDateTime.of(LocalDateTime.now(), ZoneId.of(ZoneId.systemDefault().toString())).withZoneSameInstant(ZoneId.of("Asia/Shanghai"));

        // 定义日期时间格式
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

        // 格式化日期和时间
        String formattedDateTime = shanghaiDateTime.format(formatter);
        System.out.println(formattedDateTime);
    }
}