是否有一个用于使用日期构造cron表达式的java类？

我需要根据表单中的用户输入构建一个cron表达式。 所以我有一个日期选择器和一个选择框来选择频率。 我可以很容易地从这个构建一个cron表达式，但感觉就像我正在重新发明轮子。 有没有合适的课程为我做这个？ 用类似方法的东西

public String cron(String frequency, Calendar nextRunTime); 

Answer 1

我认为石英中的Cronfunction可以为您提供此function，但您必须进行一些编程才能使其正常工作。 （ http://www.quartz-scheduler.org/docs/tutorials/crontrigger.html ）

这是我正确理解你的问题。

Answer 2

我已经创建了一个使用Quartz Scheduler的类。 请查看下面的课程及其用法

 package com.az.ws.client.utility; import java.util.Calendar; import java.util.Date; /** * @author AZ * */ public final class CronCalendarHelper_ { private final Date mStartDate; private final Calendar mStartCal; private final Date mEndDate; private final Calendar mEndCal; private final String mSecondsDuration = "0"; private final String mMinsDuration = "0/30"; private final String mDaysOfWeekDuration = "?"; private String mHoursDuration; private String mDaysOfMonthDuration; private String mMonthsDuration; private String mYearsDuration; public CronCalendarHelper_(Date pStartDate, Date pEndDate) { this.mStartDate = pStartDate; mStartCal = Calendar.getInstance(); this.mEndDate = pEndDate; mEndCal = Calendar.getInstance(); this.init(); } private void init() { mStartCal.setTime(mStartDate); mEndCal.setTime(mEndDate); String h1 = String.valueOf(mStartCal.get(Calendar.HOUR_OF_DAY)); String h2 = String.valueOf(mEndCal.get(Calendar.HOUR_OF_DAY)); this.mHoursDuration = h1 + "-" + h2; String d1 = String.valueOf(mStartCal.get(Calendar.DAY_OF_MONTH)); String d2 = String.valueOf(mEndCal.get(Calendar.DAY_OF_MONTH)); this.mDaysOfMonthDuration = d1 + "-" + d2; // First month is January which is 0, inconsistent Java Date API String m1 = new java.text.SimpleDateFormat("MM").format(mEndCal.getTime()); String m2 = new java.text.SimpleDateFormat("MM").format(mStartCal.getTime()); if (Integer.valueOf(m2) - Integer.valueOf(m1) > 0) { this.mMonthsDuration = m1 + "-" + m2; } else { this.mMonthsDuration = m1; } if (mEndCal.get(Calendar.YEAR) - mStartCal.get(Calendar.YEAR) > 0) { String y1 = String.valueOf(mStartCal.get(Calendar.YEAR)); String y2 = String.valueOf(mEndCal.get(Calendar.YEAR)); this.mYearsDuration = y1 + "-" + y2; } else { this.mYearsDuration = String.valueOf(mStartCal.get(Calendar.YEAR)); } } public Date getDate() { return mStartDate; } public String getSecondsDuration() { return mSecondsDuration; } public String getMinsDuration() { return mMinsDuration; } public String getDaysOfWeekDuration() { return mDaysOfWeekDuration; } public String getHoursDuration() { return mHoursDuration; } public String getDaysOfMonthDuration() { return mDaysOfMonthDuration; } public String getMonthsDuration() { return mMonthsDuration; } public String getYearsDuration() { return mYearsDuration; } } 

用法：

  String startDateStr = "2013-10-19 09:00:00.0"; String endDateStr = "2013-10-26 23:00:00.0"; Date startDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.S").parse(startDateStr); Date endDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.S").parse(endDateStr); CronCalendarHelper_ calHelper = new CronCalendarHelper_(startDate, endDate); String cron = calHelper.getSecondsDuration() + " " + calHelper.getMinsDuration() + " " + calHelper.getHoursDuration() + " " + calHelper.getDaysOfMonthDuration() + " " + calHelper.getMonthsDuration() + " " + calHelper.getDaysOfWeekDuration() + " " + calHelper.getYearsDuration(); System.out.println("Injecting Cron Expression " + cron); 

注意

我应该将id CronExpressionHelper而不是当前的名称，并且请参阅默认值。 您也可以为这些人编写getter / setter，但这是一个很好的起点。

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