Java时间差计算：深入理解传统API陷阱与java.time现代实践

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;
import org.apache.commons.lang3.time.DurationFormatUtils; // 假设使用此工具类

public class TimeCalculationLegacy {

    public String calculateHoursWorked() throws ParseException {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入登录时间 (HH:mm):");
        String loginTimeStr = sc.nextLine();
        System.out.println("请输入休息时长 (HH:mm):");
        String breakTimeStr = sc.nextLine();
        System.out.println("请输入登出时间 (HH:mm):");
        String logoutTimeStr = sc.nextLine();
        sc.close();

        SimpleDateFormat format = new SimpleDateFormat("HH:mm");
        Date login = format.parse(loginTimeStr);
        Date logout = format.parse(logoutTimeStr);
        Date breakPeriod = format.parse(breakTimeStr); // 问题根源

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

        // 验证休息时长
        long breakTimeinMilliseconds = breakPeriod.getTime();
        System.out.println("休息时长在毫秒表示为: " + breakTimeinMilliseconds);
        String testBreakFormat = DurationFormatUtils.formatDuration(breakTimeinMilliseconds, "HH:mm");
        System.out.println("您的休息时长为: " + testBreakFormat);

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

    public static void main(String[] args) throws ParseException {
        TimeCalculationLegacy calculator = new TimeCalculationLegacy();
        String workingTime = calculator.calculateHoursWorked();
        System.out.println("您的工作时间为: " + workingTime);
    }
}

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

public class TimeCalculationModern {

    public String calculateHoursWorkedModern() {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入登录时间 (HH:mm):");
        String loginTimeStr = sc.nextLine();
        System.out.println("请输入休息时长 (HH:mm):");
        String breakTimeStr = sc.nextLine();
        System.out.println("请输入登出时间 (HH:mm):");
        String logoutTimeStr = sc.nextLine();
        sc.close();

        // 1. 解析时间字符串为LocalTime对象
        // LocalTime表示一天中的时间，不含日期和时区信息
        LocalTime loginTime = LocalTime.parse(loginTimeStr);
        LocalTime logoutTime = LocalTime.parse(logoutTimeStr);

        // 2. 将休息时长字符串转换为Duration对象
        // 对于"HH:mm"格式的纯时长，可以先解析为LocalTime，然后计算与午夜的Duration
        LocalTime breakTimeAsLocalTime = LocalTime.parse(breakTimeStr);
        Duration breakDuration = Duration.between(LocalTime.MIDNIGHT, breakTimeAsLocalTime);

        // 3. 计算总工作时长
        // Duration.between(start, end) 计算两个LocalTime之间的时长
        Duration workDuration = Duration.between(loginTime, logoutTime).minus(breakDuration);

        // 4. 格式化结果
        // Duration本身没有直接的"HH:mm"格式化方法，
        // 可以通过将其加到LocalTime.MIDNIGHT上，再格式化LocalTime
        // 或者手动计算小时和分钟
        long totalSeconds = workDuration.getSeconds();
        long hours = totalSeconds / 3600;
        long minutes = (totalSeconds % 3600) / 60;

        String formattedWorkDuration = String.format("%02d:%02d", hours, minutes);

        // 验证休息时长
        System.out.println("休息时长在秒表示为: " + breakDuration.getSeconds());
        String formattedBreakDuration = String.format("%02d:%02d", 
                                                      breakDuration.toHours(), 
                                                      breakDuration.toMinutes() % 60);
        System.out.println("您的休息时长为: " + formattedBreakDuration);

        return formattedWorkDuration;
    }

    public static void main(String[] args) {
        TimeCalculationModern calculator = new TimeCalculationModern();
        String workingTime = calculator.calculateHoursWorkedModern();
        System.out.println("您的工作时间为: " + workingTime);
    }
}