指定时间生成cron表达式

简洁方式1：

public class CronUtils {
    private static final SimpleDateFormat sdf = new SimpleDateFormat("ss mm HH dd MM ? yyyy");

    /***
     *  功能描述：日期转换cron表达式
     * @param date
     * @return
     */
    public static String formatDateByPattern(Date date) {
        String formatTimeStr = null;
        if (Objects.nonNull(date)) {
            formatTimeStr = sdf.format(date);
        }
        return formatTimeStr;
    }

    /***
     * convert Date to cron, eg "0 07 10 15 1 ? 2016"
     * @param date  : 时间点
     * @return
     */
    public static String getCron(Date date) {
        return formatDateByPattern(date);
    }
}

拆解方式2：

package com.gsafety.operationmanagement.utils;

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

/**
 * @ClassName: CronUtil
 * @Description: Cron表达式工具类 目前支持三种常用的cron表达式 1.每天的某个时间点执行 例:12 12 12 * *
 *               ?表示每天12时12分12秒执行 2.每周的哪几天执行 例:12 12 12 ? * 1,2,3表示每周的周1周2周3
 *               ,12时12分12秒执行 3.每月的哪几天执行 例:12 12 12 1,21,13 * ?表示每月的1号21号13号
 *               12时12分12秒执行
 * 
 */
public class CronUtil {

    /**
     * 
     * 方法摘要：构建Cron表达式
     * 
     * @param taskScheduleModel
     * @return String
     */
    public static String createCronExpression(TaskScheduleModel taskScheduleModel) {
        StringBuffer cronExp = new StringBuffer("");
        if (null == taskScheduleModel.getJobType()) {
            System.out.println("执行周期未配置");// 执行周期未配置
        }
        if (null != taskScheduleModel.getSecond() && null != taskScheduleModel.getMinute()
                && null != taskScheduleModel.getHour()) {
            // 秒
            cronExp.append(taskScheduleModel.getSecond()).append(" ");
            // 分
            cronExp.append(taskScheduleModel.getMinute()).append(" ");
            // 小时
            cronExp.append(taskScheduleModel.getHour()).append(" ");

            // 每天
            if (taskScheduleModel.getJobType().intValue() == 1) {
                cronExp.append("* ");// 日
                cronExp.append("* ");// 月
                cronExp.append("?");// 周
            }
            // 按每周
            else if (taskScheduleModel.getJobType().intValue() == 3) {
                // 一个月中第几天
                cronExp.append("? ");
                // 月份
                cronExp.append("* ");
                // 周
                Integer[] weeks = taskScheduleModel.getDayOfWeeks();
                for (int i = 0; i < weeks.length; i++) {
                    if (i == 0) {
                        cronExp.append(weeks[i]);
                    } else {
                        cronExp.append(",").append(weeks[i]);
                    }
                }
            }
            // 按每月
            else if (taskScheduleModel.getJobType().intValue() == 2) {
                // 一个月中的哪几天
                Integer[] days = taskScheduleModel.getDayOfMonths();
                for (int i = 0; i < days.length; i++) {
                    if (i == 0) {
                        cronExp.append(days[i]);
                    } else {
                        cronExp.append(",").append(days[i]);
                    }
                }
                // 月份
                cronExp.append(" * ");
                // 周
                cronExp.append("?");
            }
        } else {
            System.out.println("时或分或秒参数未配置");// 时或分或秒参数未配置
        }
        return cronExp.toString();
    }

    /**
     * 
     * 方法摘要：生成计划的详细描述
     * 
     * @param taskScheduleModel
     * @return String
     */
    public static String createDescription(TaskScheduleModel taskScheduleModel) {
        StringBuffer description = new StringBuffer("");
        // 计划执行开始时间
        // Date startTime = taskScheduleModel.getScheduleStartTime();

        if (null != taskScheduleModel.getSecond() && null != taskScheduleModel.getMinute()
                && null != taskScheduleModel.getHour()) {
            // 按每天
            if (taskScheduleModel.getJobType().intValue() == 1) {
                description.append("每天");
                description.append(taskScheduleModel.getHour()).append("时");
                description.append(taskScheduleModel.getMinute()).append("分");
                description.append(taskScheduleModel.getSecond()).append("秒");
                description.append("执行");
            }

            // 按每周
            else if (taskScheduleModel.getJobType().intValue() == 3) {
                if (taskScheduleModel.getDayOfWeeks() != null && taskScheduleModel.getDayOfWeeks().length > 0) {
                    String days = "";
                    for (int i : taskScheduleModel.getDayOfWeeks()) {
                        days += "周" + i;
                    }
                    description.append("每周的").append(days).append(" ");
                }
                if (null != taskScheduleModel.getSecond() && null != taskScheduleModel.getMinute()
                        && null != taskScheduleModel.getHour()) {
                    description.append(",");
                    description.append(taskScheduleModel.getHour()).append("时");
                    description.append(taskScheduleModel.getMinute()).append("分");
                    description.append(taskScheduleModel.getSecond()).append("秒");
                }
                description.append("执行");
            }

            // 按每月
            else if (taskScheduleModel.getJobType().intValue() == 2) {
                // 选择月份
                if (taskScheduleModel.getDayOfMonths() != null && taskScheduleModel.getDayOfMonths().length > 0) {
                    String days = "";
                    for (int i : taskScheduleModel.getDayOfMonths()) {
                        days += i + "号";
                    }
                    description.append("每月的").append(days).append(" ");
                }
                description.append(taskScheduleModel.getHour()).append("时");
                description.append(taskScheduleModel.getMinute()).append("分");
                description.append(taskScheduleModel.getSecond()).append("秒");
                description.append("执行");
            }

        }
        return description.toString();
    }

    // 参考例子
    public static void main(String[] args) {
        // 执行时间：每天的12时12分12秒 start
        TaskScheduleModel taskScheduleModel = new TaskScheduleModel();
        taskScheduleModel.setJobType(1);// 按每天
        Integer hour = 12; // 时
        Integer minute = 12; // 分
        Integer second = 12; // 秒
        taskScheduleModel.setHour(hour);
        taskScheduleModel.setMinute(minute);
        taskScheduleModel.setSecond(second);
        String cropExp = createCronExpression(taskScheduleModel);
        System.out.println(cropExp + ":" + createDescription(taskScheduleModel));
        // 执行时间：每天的12时12分12秒 end

        taskScheduleModel.setJobType(3);// 每周的哪几天执行
        Integer[] dayOfWeeks = new Integer[3];
        dayOfWeeks[0] = 1;
        dayOfWeeks[1] = 2;
        dayOfWeeks[2] = 3;
        taskScheduleModel.setDayOfWeeks(dayOfWeeks);
        cropExp = createCronExpression(taskScheduleModel);
        System.out.println(cropExp + ":" + createDescription(taskScheduleModel));

        taskScheduleModel.setJobType(2);// 每月的哪几天执行
        Integer[] dayOfMonths = new Integer[3];
        dayOfMonths[0] = 1;
        dayOfMonths[1] = 21;
        dayOfMonths[2] = 13;
        taskScheduleModel.setDayOfMonths(dayOfMonths);
        cropExp = createCronExpression(taskScheduleModel);
        System.out.println(cropExp + ":" + createDescription(taskScheduleModel));

    }
    /**
     * 通过输入指定日期时间生成cron表达式
     * @param date
     * @return cron表达式
     */
    public static  String getCron(Date date){
        String dateFormat="ss mm HH dd MM ? yyyy";
        SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
        String formatTimeStr = null;
        if (date != null) {
            formatTimeStr = sdf.format(date);
        }
 
        return formatTimeStr;
    }
}