Java中精确计算时间差：告别Date与SimpleDateFormat的陷阱

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

public class TimeCalculationLegacy {

    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(); // 例如输入 "02:00"
        System.out.println("Please enter your logout time (HH:mm):");
        logoutTime = sc.nextLine();
        sc.close(); // 实际项目中应更严谨处理资源关闭

        SimpleDateFormat format = new SimpleDateFormat("HH:mm");
        Date login = format.parse(loginTime);
        Date logout = format.parse(logoutTime);
        Date breakPeriod = format.parse(breakTime); // 解析 "02:00"

        // 计算总工作时长（毫秒）
        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 "02:00"，实际可能为 "01:00"

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

    public static void main(String[] args) throws ParseException {
        TimeCalculationLegacy calculator = new TimeCalculationLegacy();
        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 (输入02:00，但输出01:00)
Your working time is: 07:00 (预期为 6:00)

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

public class TimeCalculationModern {

    public String calculateHoursWorked() {
        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 breakDurationStr = sc.nextLine(); // 例如输入 "02:00"
        System.out.println("Please enter your logout time (HH:mm):");
        String logoutTimeStr = sc.nextLine();
        sc.close();

        // 定义时间格式化器
        DateTimeFormatter timeFormatter = DateTimeFormatter.ofPattern("HH:mm");

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

        // 解析休息时长。关键在于将 "HH:mm" 视为一个持续时间，而不是一个时间点。
        // LocalTime.parse("HH:mm") 可以得到一个时间点，然后通过与LocalTime.MIDNIGHT的Duration来表示时长。
        LocalTime breakDurationAsTime = LocalTime.parse(breakDurationStr, timeFormatter);
        Duration breakDuration = Duration.between(LocalTime.MIDNIGHT, breakDurationAsTime);

        // 计算工作时长
        // Duration.between(start, end) 计算两个时间点之间的持续时间
        Duration workDuration = Duration.between(login, logout);

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

        // 格式化输出结果
        // Duration本身没有直接格式化为HH:mm的方法，可以转换为LocalTime再格式化
        // 假设结果不会超过24小时
        String formattedWorkTime = LocalTime.MIDNIGHT.plus(totalHoursWorked).format(timeFormatter);

        System.out.println("Your break duration is: " + LocalTime.MIDNIGHT.plus(breakDuration).format(timeFormatter));
        return formattedWorkTime;
    }

    public static void main(String[] args) {
        TimeCalculationModern calculator = new TimeCalculationModern();
        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
Your break duration is: 02:00
Your working time is: 06:00