JAVA 计算指定工作日的工时 单位（分钟） 1.传入工作时段字符串，格式为String（HH:mm-HH:mm;HH:mm-HH:mm;HH:mm-HH:mm）， 2.传入工作起止日期时间（Date类型） 3.传入一个指定年月日（Date类型） 4.计算第三步中指定的这天工作日共工作了多少（分钟）

以下是一个计算指定工作日工时的 Java 代码示例：

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class WorkHourCalculator {
    public static void main(String[] args) throws Exception {
        String workingHours = "09:00-12:00;13:00-18:00"; // 工作时间段
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        Date startDate = dateFormat.parse("2021-03-01 09:00:00"); // 工作起始时间
        Date endDate = dateFormat.parse("2021-03-31 18:00:00"); // 工作结束时间
        Date targetDate = dateFormat.parse("2021-03-15 12:00:00"); // 指定日期

        long workMinutes = calculateWorkMinutes(workingHours, startDate, endDate, targetDate);
        System.out.println("工作日工时：" + workMinutes + " 分钟");
    }

    private static long calculateWorkMinutes(String workingHours, Date startDate, Date endDate, Date targetDate) throws Exception {
        SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm");
        Calendar startCalendar = Calendar.getInstance();
        startCalendar.setTime(startDate);
        Calendar endCalendar = Calendar.getInstance();
        endCalendar.setTime(endDate);

        long workMinutes = 0;
        if (!startCalendar.after(endCalendar)) { // 判断起始时间是否在结束时间之前
            Calendar targetCalendar = Calendar.getInstance();
            targetCalendar.setTime(targetDate);
            targetCalendar.set(Calendar.HOUR_OF_DAY, 0);
            targetCalendar.set(Calendar.MINUTE, 0);
            targetCalendar.set(Calendar.SECOND, 0);
            targetCalendar.set(Calendar.MILLISECOND, 0);

            while (!startCalendar.after(endCalendar)) { // 遍历起始时间和结束时间之间的每一天
                if (isWorkDay(workingHours, startCalendar)) { // 判断当前日期是否为工作日
                    if (targetCalendar.equals(startCalendar)) { // 判断当前日期是否为指定日期
                        workMinutes += calculateWorkMinutesForDay(workingHours, startCalendar, targetDate);
                        break;
                    } else {
                        workMinutes += calculateWorkMinutesForDay(workingHours, startCalendar, null);
                    }
                }
                startCalendar.add(Calendar.DAY_OF_YEAR, 1);
            }
        }

        return workMinutes;
    }

    private static boolean isWorkDay(String workingHours, Calendar calendar) throws Exception {
        SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm");
        String[] workingHoursArray = workingHours.split(";");
        for (String workingHoursItem : workingHoursArray) {
            String[] workingHoursItemArray = workingHoursItem.split("-");
            Date startTime = dateFormat.parse(workingHoursItemArray[0]);
            Date endTime = dateFormat.parse(workingHoursItemArray[1]);
            Calendar startCalendar = Calendar.getInstance();
            startCalendar.setTime(startTime);
            Calendar endCalendar = Calendar.getInstance();
            endCalendar.setTime(endTime);
            if (calendar.get(Calendar.HOUR_OF_DAY) >= startCalendar.get(Calendar.HOUR_OF_DAY) &&
                    calendar.get(Calendar.MINUTE) >= startCalendar.get(Calendar.MINUTE) &&
                    calendar.get(Calendar.HOUR_OF_DAY) < endCalendar.get(Calendar.HOUR_OF_DAY) ||
                    (calendar.get(Calendar.HOUR_OF_DAY) == endCalendar.get(Calendar.HOUR_OF_DAY) &&
                            calendar.get(Calendar.MINUTE) <= endCalendar.get(Calendar.MINUTE))) {
                return true;
            }
        }
        return false;
    }

    private static long calculateWorkMinutesForDay(String workingHours, Calendar calendar, Date targetDate) throws Exception {
        SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm");
        String[] workingHoursArray = workingHours.split(";");
        long workMinutes = 0;
        for (String workingHoursItem : workingHoursArray) {
            String[] workingHoursItemArray = workingHoursItem.split("-");
            Date startTime = dateFormat.parse(workingHoursItemArray[0]);
            Date endTime = dateFormat.parse(workingHoursItemArray[1]);
            Calendar startCalendar = Calendar.getInstance();
            startCalendar.setTime(startTime);
            Calendar endCalendar = Calendar.getInstance();
            endCalendar.setTime(endTime);
            if (targetDate != null && calendar.equals(startCalendar)) { // 如果当前日期是指定日期，则计算当日剩余工时
                workMinutes += calculateWorkMinutesBetweenTimes(calendar.getTime(), endTime);
            } else if (targetDate != null && calendar.equals(endCalendar)) { // 如果当前日期是指定日期，则计算当日已完成工时
                workMinutes += calculateWorkMinutesBetweenTimes(startTime, calendar.getTime());
                break;
            } else { // 如果当前日期不是指定日期，则计算当日全部工时
                workMinutes += calculateWorkMinutesBetweenTimes(startTime, endTime);
            }
        }
        return workMinutes;
    }

    private static long calculateWorkMinutesBetweenTimes(Date startTime, Date endTime) {
        long startMillis = startTime.getTime();
        long endMillis = endTime.getTime();
        long interval = endMillis - startMillis;
        return interval / (1000 * 60);
    }
}

在上述代码中，`calculateWorkMinutes` 方法用于计算指定日期的工作分钟数。该方法首先遍历起始时间和结束时间之间的每一天，然后判断每一天是否为工作日。如果当前日期是指定日期，则计算当日剩余工时或已完成工时；否则计算当日全部工时。最终将所有工作日的工时相加得到总工时。`isWorkDay` 方法用于判断当前日期是否为工作日，`calculateWorkMinutesForDay` 方法用于计算指定日期的工作分钟数。

需要注意的是，上述代码中的时间字符串格式为 "HH:mm"，日期时间字符串格式为 "yyyy-MM-dd HH:mm:ss"，可以根据实际情况进行调整。此外，上述代码还做了一些异常处理，需要在方法调用中进行异常捕获或抛出。