Java中精确计算时间差与避免时区陷阱的教程

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;
import org.apache.commons.lang3.time.DurationFormatUtils; // 假设已引入此库

public class TimeDifferenceCalculator {

    private String loginTime;
    private String breakTime;
    private String logoutTime;

    public String calculateHoursWorked() throws ParseException {
        Scanner sc = new Scanner(System.in);
        System.out.println("Please enter your login time (HH:mm):");
        loginTime = sc.nextLine();
        System.out.println("Please enter your break duration (HH:mm):");
        breakTime = sc.nextLine();
        System.out.println("Please enter your logout time (HH:mm):");
        logoutTime = sc.nextLine();

        SimpleDateFormat format = new SimpleDateFormat("HH:mm");
        Date login = format.parse(loginTime);
        Date logout = format.parse(logoutTime);
        Date breakPeriod = format.parse(breakTime); // 这里是问题的关键

        // 计算总工作时长
        long totalHoursWorked = logout.getTime() - login.getTime() - breakPeriod.getTime();

        // 验证休息时间
        long breakTimeinMilliseconds = breakPeriod.getTime();
        System.out.println("So our break time in ms is: " + breakTimeinMilliseconds);
        String test = DurationFormatUtils.formatDuration(breakTimeinMilliseconds, "HH:mm");
        System.out.println("Your break time is: " + test); // 预期输出 02:00, 实际输出 01:00

        return DurationFormatUtils.formatDuration(totalHoursWorked, "HH:mm");
    }

    public static void main(String[] args) throws ParseException {
        TimeDifferenceCalculator calculator = new TimeDifferenceCalculator();
        System.out.println("Your working time is: " + calculator.calculateHoursWorked());
    }
}

Please enter your login time (HH:mm):
02:00
Please enter your break duration (HH:mm):
02:00
Please enter your logout time (HH:mm):
10:00
So our break time in ms is: 3600000
Your break time is: 01:00
Your working time is: 07:00

import java.time.Duration;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import java.util.Scanner;

public class ModernTimeDifferenceCalculator {

    public String calculateHoursWorkedModern() {
        Scanner sc = new Scanner(System.in);
        System.out.println("Please enter your login time (HH:mm):");
        String loginTimeStr = sc.nextLine();
        System.out.println("Please enter your break duration (HH:mm):");
        String breakTimeStr = sc.nextLine();
        System.out.println("Please enter your logout time (HH:mm):");
        String logoutTimeStr = sc.nextLine();
        sc.close(); // 关闭Scanner

        // 定义时间格式器，用于解析和格式化HH:mm格式的时间
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("HH:mm");

        // 解析登录和登出时间为LocalTime对象
        LocalTime login = LocalTime.parse(loginTimeStr, formatter);
        LocalTime logout = LocalTime.parse(logoutTimeStr, formatter);

        // 解析休息时长。
        // 由于LocalTime.parse("HH:mm")解析的是一天中的某个时间点，
        // 而我们想要的是一个持续时间，所以需要将其转换为Duration。
        // 最简单的方法是计算从午夜到该时间点的Duration。
        LocalTime breakDurationTime = LocalTime.parse(breakTimeStr, formatter);
        Duration breakDuration = Duration.between(LocalTime.MIDNIGHT, breakDurationTime);

        // 计算总工作时长：登出时间与登录时间之间的Duration
        Duration workDuration = Duration.between(login, logout);

        // 减去休息时长
        Duration totalWorkDuration = workDuration.minus(breakDuration);

        // 格式化输出最终结果
        // Duration本身没有直接的HH:mm格式化方法，
        // 可以通过将其加到午夜LocalTime上，再格式化LocalTime来实现。
        // 或者手动计算小时和分钟。
        long totalMinutes = totalWorkDuration.toMinutes();
        long hours = totalMinutes / 60;
        long minutes = totalMinutes % 60;

        return String.format("%02d:%02d", hours, minutes);
    }

    public static void main(String[] args) {
        ModernTimeDifferenceCalculator calculator = new ModernTimeDifferenceCalculator();
        System.out.println("Your working time is: " + calculator.calculateHoursWorkedModern());
    }
}

Please enter your login time (HH:mm):
02:00
Please enter your break duration (HH:mm):
02:00
Please enter your logout time (HH:mm):
10:00
Your working time is: 06:00