A tool class for generating, parsing and computing Cron expressions in Java

This article introduces the generation of cron expressions through java, parsing expressions, and calculating the execution date of expressions

1. Generate expressions

public static String createCronExpression(CronModel cronModel){
    
    
        StringBuilder cronExp = new StringBuilder();

        if(null == cronModel.getJobType()) {
    
    
            System.out.println("执行周期未配置" );//执行周期未配置
        }

        if (null != cronModel.getSecond()
                && null != cronModel.getMinute()
                && null != cronModel.getHour()) {
    
    
            //秒
            cronExp.append(cronModel.getSecond()).append(" ");
            //分
            cronExp.append(cronModel.getMinute()).append(" ");
            //小时
            cronExp.append(cronModel.getHour()).append(" ");
            //每天
            if(cronModel.getJobType().getValue() == 1){
    
    
                //12 12 12 1/2 * ? *
                //12 12 12 * * ?
                if(cronModel.getBeApart()!=null){
    
    
                    cronExp.append("1");//日
                    cronExp.append("/");
                    cronExp.append(cronModel.getBeApart()+1);//月
                    cronExp.append(" ");
                    cronExp.append("* ");
                    cronExp.append("?");
                }else {
    
    
                    cronExp.append("* ");//日
                    cronExp.append("* ");//月
                    cronExp.append("?");
                }
            }

            //按每周
            else if(cronModel.getJobType().getValue() == 3){
    
    
                //一个月中第几天
                cronExp.append("? ");
                //月份
                cronExp.append("* ");
                //周
                Integer[] weeks = cronModel.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(cronModel.getJobType().getValue()== 2){
    
    
                //一个月中的哪几天
                Integer[] days = cronModel.getDayOfMonths();
                for(int i = 0; i < days.length; i++){
    
    
                    if(i == 0){
    
    
                        if(days[i]==32){
    
    
                            //本月最后一天
                            String endMouthCron="0 0 0 L * ?";
                            return endMouthCron;
                        }else {
    
    
                            cronExp.append(days[i]);
                        }
                    } else{
    
    
                        cronExp.append(",").append(days[i]);
                    }
                }
                //月份
                cronExp.append(" * ");
                //周
                cronExp.append("?");
            }
            //按每年
            else if(cronModel.getJobType().getValue()== 4){
    
    
                //一个年中的哪几天
                Integer[] days = cronModel.getDayOfMonths();
                if(ArrayUtil.isEmpty(days)){
    
    
                    cronExp.append("*");
                }else{
    
    
                    for(int i = 0; i < days.length; i++){
    
    
                        if(i == 0){
    
    
                            cronExp.append(days[i]);
                        } else{
    
    
                            cronExp.append(",").append(days[i]);
                        }
                    }
                }
                //月份
                Integer[] months = cronModel.getMonths();
                if (ArrayUtil.isEmpty(months)) {
    
    
                    cronExp.append(" *");
                }else{
    
    
                    for (int i = 0; i < months.length; i++){
    
    
                        Integer month = months[i];
                        if (month > 12){
    
    
                            throw new RuntimeException("月份数据异常: "+ Arrays.toString(months));
                        }
                        if(i == 0){
    
    
                            cronExp.append(" ").append(month);
                        }else{
    
    
                            cronExp.append(",").append(month);
                        }
                    }
                }
                cronExp.append(" ?");
            }
            else if(cronModel.getJobType().getValue() == 0){
    
    
                cronExp.append("* ");//日
                cronExp.append("* ");//月
                cronExp.append("?");//周
            }
        }
        return cronExp.toString();
    }

public static String createLoopCronExpression(int rate, int cycle) {
    
    
        String cron = "";
        switch (rate) {
    
    
            case 0:// 每cycle秒执行一次
                cron = "0/" + cycle + " * * * * ?";
                break;
            case 1:// 每cycle分钟执行一次
                cron = "0 0/" + cycle + " * * * ?";
                break;
            case 2:// 每cycle小时执行一次
                cron = "0 0 0/" + cycle + " * * ?";
                break;
            case 3:// 每cycle天的0点执行一次
                cron = "0 0 0 1/" + cycle + " * ?";
                break;
            case 4:// 每cycle月的1号0点执行一次
                cron = "0 0 0 1 1/" + cycle + " ? ";
                break;
            case 5://  每天cycle点执行一次
                cron = "0 0 " + cycle+ "  * * ?";
                break;
            default:// 默认每cycle秒执行一次
                cron = "0/1 * * * * ?";
                break;
        }
        return cron;
    }

2. Parsing expressions

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

        if (null != cronModel.getSecond()
                && null != cronModel.getMinute()
                && null != cronModel.getHour()) {
    
    
            //按每天
            if(cronModel.getJobType().getValue() == 1){
    
    
                Integer beApart = cronModel.getBeApart();
                if(beApart !=null){
    
    
                    description.append("每间隔").append(beApart).append("天");
                }else{
    
    
                    description.append("每天");
                }
                description.append(cronModel.getHour()).append("时");
                description.append(cronModel.getMinute()).append("分");
                description.append(cronModel.getSecond()).append("秒");
                description.append("执行");
            }

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

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

        }
        return description.toString();
    }

3. Calculate expression execution date

Quartz dependency needs to be introduced

<dependency>
    <groupId>quartz</groupId>
    <artifactId>quartz</artifactId>
    <version>1.5.2</version>
</dependency>

/**
     * 计算表达式最近几次执行时间
     * @param cronExpress 表达式
     * @param num 次数
     * @return 时间集合
     */
    public static List<String> getCronNextTimes(String cronExpress,Integer num){
    
    
        if(StrUtil.isEmpty(cronExpress)){
    
    
            throw new RuntimeException("cron 表达式不能为空");
        }
        //判断cron表达式
        if(!CronSequenceGenerator.isValidExpression(cronExpress)){
    
    
            throw new RuntimeException("cron 表达式格式不正确,cron: "+cronExpress);
        }
        if(num == null || num == 0){
    
    
            num = 1;
        }
        List<String> list = new ArrayList<>();
        CronTrigger cronTrigger = new CronTrigger();
        try {
    
    
            cronTrigger.setCronExpression(cronExpress);
        } catch (ParseException e) {
    
    
            throw new RuntimeException("cron表达式不正确,cron: "+cronExpress);
        }
        List<Date> dates = TriggerUtils.computeFireTimes(cronTrigger, null, num);
        String format = "yyyy-MM-dd HH:mm:ss";
        for (Date date : dates) {
    
    
            list.add(DateUtil.format(date,format));
        }
        return list;
    }

4. Test

public static void main(String[] args) {
    
    
        CronModel cronModel = new CronModel();
        cronModel.setJobType(JobEnum.DAY);//按每天
        //每隔几天执行
        cronModel.setBeApart(1);
        String cropExp = createCronExpression(cronModel);
        System.out.println(cropExp + ":" + createDescription(cronModel));
        //执行时间：每天的12时12分12秒 end
        System.out.println(getCronNextTimes(cropExp, 5));

        cronModel.setJobType(JobEnum.WEEK);//每周的哪几天执行
        Integer[] dayOfWeeks = new Integer[3];
        dayOfWeeks[0] = 1;
        dayOfWeeks[1] = 2;
        dayOfWeeks[2] = 3;
        cronModel.setDayOfWeeks(dayOfWeeks);
        cronModel.setJobType(JobEnum.WEEK);
        cropExp = createCronExpression(cronModel);
        System.out.println(cropExp + ":" + createDescription(cronModel));
        System.out.println(getCronNextTimes(cropExp, 5));

        cronModel.setJobType(JobEnum.MONTH);//每月的哪几天执行
        Integer[] dayOfMonths = new Integer[3];
        dayOfMonths[0] = 1;
        dayOfMonths[1] = 21;
        dayOfMonths[2] = 13;
        cronModel.setDayOfMonths(dayOfMonths);
        cropExp = createCronExpression(cronModel);
        System.out.println(cropExp + ":" + createDescription(cronModel));
        System.out.println(getCronNextTimes(cropExp, 5));

        cronModel.setJobType(JobEnum.EVERY);//每天的几点几分几秒开始
        cropExp = createCronExpression(cronModel);
        System.out.println(cropExp);
        System.out.println(getCronNextTimes(cropExp, 5));

    }

5. Complete code

gitee address:

https://gitee.com/zhenglm/tools.git

/**
 * @author zlm
 * @date 2023/8/3
 */
public enum JobEnum {
    
    

    EVERY("每天",0),
    DAY("日",1),
    MONTH("月",2),
    WEEK("周",3),
    YEAR("年",4),
    ;

    JobEnum(String name,Integer value) {
    
    
        this.name = name;
        this.value = value;
    }

    private final String name;
    private final Integer value;

    public Integer getValue() {
    
    
        return value;
    }

    public String getName() {
    
    
        return name;
    }
}

public class CronModel {
    
    

    Integer[] dayOfWeeks;

    Integer[] dayOfMonths;

    Integer[] months;

    Integer second;

    Integer minute;

    Integer hour;

    /**
     * 类型
     */
    JobEnum jobType;
    /**
     * 间隔
     */
    Integer beApart;

    public Integer[] getDayOfWeeks() {
    
    
        return dayOfWeeks;
    }

    public void setDayOfWeeks(Integer[] dayOfWeeks) {
    
    
        this.dayOfWeeks = dayOfWeeks;
    }

    public Integer[] getDayOfMonths() {
    
    
        return dayOfMonths;
    }

    public void setDayOfMonths(Integer[] dayOfMonths) {
    
    
        this.dayOfMonths = dayOfMonths;
    }

    public Integer[] getMonths() {
    
    
        return months;
    }

    public void setMonths(Integer[] months) {
    
    
        this.months = months;
    }

    public Integer getSecond() {
    
    
        return second == null ? 0 : second;
    }

    public void setSecond(Integer second) {
    
    
        this.second = second;
    }

    public Integer getMinute() {
    
    
        return minute == null ? 0 : minute;
    }

    public void setMinute(Integer minute) {
    
    
        this.minute = minute;
    }

    public Integer getHour() {
    
    

        return hour==null ? 0 : hour;
    }

    public void setHour(Integer hour) {
    
    
        this.hour = hour;
    }

    public JobEnum getJobType() {
    
    
        return jobType == null ? JobEnum.DAY : jobType;
    }

    public void setJobType(JobEnum jobType) {
    
    
        this.jobType = jobType;
    }

    public Integer getBeApart() {
    
    
        return beApart;
    }

    public void setBeApart(Integer beApart) {
    
    
        this.beApart = beApart;
    }
}

/**
 * @author zlm
 * @date 2023/8/3
 *
 * 字段 允许值 允许的特殊字符
 * 秒 0-59 , - * /
 * 分 0-59 , - * /
 * 小时 0-23 , - * /
 * 日期 1-31 , - * ? / L W C
 * 月份 1-12 或者 JAN-DEC , - * /
 * 星期 1-7 或者 SUN-SAT , - * ? / L C #
 * 年（可选） 留空, 1970-2099 , - * /
 *
 * * 表示所有值；
 * ? 表示未说明的值，即不关心它为何值；
 * - 表示一个指定的范围；
 * , 表示附加一个可能值；
 * / 符号前表示开始时间，符号后表示每次递增的值；
 * L("last") ("last") "L" 用在day-of-month字段意思是 "这个月最后一天"；用在 day-of-week字段, 它简单意思是 "7" or "SAT"。 如果在day-of-week字段里和数字联合使用，它的意思就是 "这个月的最后一个星期几" – 例如： "6L" means "这个月的最后一个星期五". 当我们用“L”时，不指明一个列表值或者范围是很重要的，不然的话，我们会得到一些意想不到的结果。
 * W("weekday") 只能用在day-of-month字段。用来描叙最接近指定天的工作日（周一到周五）。例如：在day-of-month字段用“15W”指“最接近这个 月第15天的工作日”，即如果这个月第15天是周六，那么触发器将会在这个月第14天即周五触发；如果这个月第15天是周日，那么触发器将会在这个月第 16天即周一触发；如果这个月第15天是周二，那么就在触发器这天触发。注意一点：这个用法只会在当前月计算值，不会越过当前月。“W”字符仅能在 day-of-month指明一天，不能是一个范围或列表。也可以用“LW”来指定这个月的最后一个工作日。
 * # 只能用在day-of-week字段。用来指定这个月的第几个周几。例：在day-of-week字段用"6#3"指这个月第3个周五（6指周五，3指第3个）。如果指定的日期不存在，触发器就不会触发。
 * C 指和calendar联系后计算过的值。例：在day-of-month 字段用“5C”指在这个月第5天或之后包括calendar的第一天；在day-of-week字段用“1C”指在这周日或之后包括calendar的第一天。
 *
 *
 */
public class CronUtil {
    
    
    
    /**
     * 计算表达式最近几次执行时间
     * @param cronExpress 表达式
     * @param num 次数
     * @return 时间集合
     */
    public static List<String> getCronNextTimes(String cronExpress,Integer num){
    
    
        if(StrUtil.isEmpty(cronExpress)){
    
    
            throw new RuntimeException("cron 表达式不能为空");
        }
        //判断cron表达式
        if(!CronSequenceGenerator.isValidExpression(cronExpress)){
    
    
            throw new RuntimeException("cron 表达式格式不正确,cron: "+cronExpress);
        }
        if(num == null || num == 0){
    
    
            num = 1;
        }
        List<String> list = new ArrayList<>();
        CronTrigger cronTrigger = new CronTrigger();
        try {
    
    
            cronTrigger.setCronExpression(cronExpress);
        } catch (ParseException e) {
    
    
            throw new RuntimeException("cron表达式不正确,cron: "+cronExpress);
        }
        List<Date> dates = TriggerUtils.computeFireTimes(cronTrigger, null, num);
        String format = "yyyy-MM-dd HH:mm:ss";
        for (Date date : dates) {
    
    
            list.add(DateUtil.format(date,format));
        }
        return list;
    }

    /**
     *  构建Cron表达式
     * 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 static String createCronExpression(CronModel cronModel){
    
    
        StringBuilder cronExp = new StringBuilder();

        if(null == cronModel.getJobType()) {
    
    
            System.out.println("执行周期未配置" );//执行周期未配置
        }

        if (null != cronModel.getSecond()
                && null != cronModel.getMinute()
                && null != cronModel.getHour()) {
    
    
            //秒
            cronExp.append(cronModel.getSecond()).append(" ");
            //分
            cronExp.append(cronModel.getMinute()).append(" ");
            //小时
            cronExp.append(cronModel.getHour()).append(" ");
            //每天
            if(cronModel.getJobType().getValue() == 1){
    
    
                //12 12 12 1/2 * ? *
                //12 12 12 * * ?
                if(cronModel.getBeApart()!=null){
    
    
                    cronExp.append("1");//日
                    cronExp.append("/");
                    cronExp.append(cronModel.getBeApart()+1);//月
                    cronExp.append(" ");
                    cronExp.append("* ");
                    cronExp.append("?");
                }else {
    
    
                    cronExp.append("* ");//日
                    cronExp.append("* ");//月
                    cronExp.append("?");//周
                }
            }

            //按每周
            else if(cronModel.getJobType().getValue() == 3){
    
    
                //一个月中第几天
                cronExp.append("? ");
                //月份
                cronExp.append("* ");
                //周
                Integer[] weeks = cronModel.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(cronModel.getJobType().getValue()== 2){
    
    
                //一个月中的哪几天
                Integer[] days = cronModel.getDayOfMonths();
                for(int i = 0; i < days.length; i++){
    
    
                    if(i == 0){
    
    
                        if(days[i]==32){
    
    
                            //本月最后一天
                            String endMouthCron="0 0 0 L * ?";
                            return endMouthCron;
                        }else {
    
    
                            cronExp.append(days[i]);
                        }
                    } else{
    
    
                        cronExp.append(",").append(days[i]);
                    }
                }
                //月份
                cronExp.append(" * ");
                //周
                cronExp.append("?");
            }
            //按每年
            else if(cronModel.getJobType().getValue()== 4){
    
    
                //一个年中的哪几天
                Integer[] days = cronModel.getDayOfMonths();
                if(ArrayUtil.isEmpty(days)){
    
    
                    cronExp.append("*");
                }else{
    
    
                    for(int i = 0; i < days.length; i++){
    
    
                        if(i == 0){
    
    
                            cronExp.append(days[i]);
                        } else{
    
    
                            cronExp.append(",").append(days[i]);
                        }
                    }
                }
                //月份
                Integer[] months = cronModel.getMonths();
                if (ArrayUtil.isEmpty(months)) {
    
    
                    cronExp.append(" *");
                }else{
    
    
                    for (int i = 0; i < months.length; i++){
    
    
                        Integer month = months[i];
                        if (month > 12){
    
    
                            throw new RuntimeException("月份数据异常: "+ Arrays.toString(months));
                        }
                        if(i == 0){
    
    
                            cronExp.append(" ").append(month);
                        }else{
    
    
                            cronExp.append(",").append(month);
                        }
                    }
                }
                cronExp.append(" ?");
            }
            else if(cronModel.getJobType().getValue() == 0){
    
    
                cronExp.append("* ");//日
                cronExp.append("* ");//月
                cronExp.append("?");//周
            }
        }
        return cronExp.toString();
    }

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

        if (null != cronModel.getSecond()
                && null != cronModel.getMinute()
                && null != cronModel.getHour()) {
    
    
            //按每天
            if(cronModel.getJobType().getValue() == 1){
    
    
                Integer beApart = cronModel.getBeApart();
                if(beApart !=null){
    
    
                    description.append("每间隔").append(beApart).append("天");
                }else{
    
    
                    description.append("每天");
                }
                description.append(cronModel.getHour()).append("时");
                description.append(cronModel.getMinute()).append("分");
                description.append(cronModel.getSecond()).append("秒");
                description.append("执行");
            }

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

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

        }
        return description.toString();
    }


    /**
     * 构建Cron表达式
     * @param rate 第几位
     * @param cycle 数值
     * @return
     */
    public static String createLoopCronExpression(int rate, int cycle) {
    
    
        String cron = "";
        switch (rate) {
    
    
            case 0:// 每cycle秒执行一次
                cron = "0/" + cycle + " * * * * ?";
                break;
            case 1:// 每cycle分钟执行一次
                cron = "0 0/" + cycle + " * * * ?";
                break;
            case 2:// 每cycle小时执行一次
                cron = "0 0 0/" + cycle + " * * ?";
                break;
            case 3:// 每cycle天的0点执行一次
                cron = "0 0 0 1/" + cycle + " * ?";
                break;
            case 4:// 每cycle月的1号0点执行一次
                cron = "0 0 0 1 1/" + cycle + " ? ";
                break;
            case 5://  每天cycle点执行一次
                cron = "0 0 " + cycle+ "  * * ?";
                break;
            default:// 默认每cycle秒执行一次
                cron = "0/1 * * * * ?";
                break;
        }
        return cron;
    }

    public static void main(String[] args) {
    
    
        CronModel cronModel = new CronModel();
        cronModel.setJobType(JobEnum.DAY);//按每天
        //每隔几天执行
        cronModel.setBeApart(1);
        String cropExp = createCronExpression(cronModel);
        System.out.println(cropExp + ":" + createDescription(cronModel));
        //执行时间：每天的12时12分12秒 end
        System.out.println(getCronNextTimes(cropExp, 5));

        cronModel.setJobType(JobEnum.WEEK);//每周的哪几天执行
        Integer[] dayOfWeeks = new Integer[3];
        dayOfWeeks[0] = 1;
        dayOfWeeks[1] = 2;
        dayOfWeeks[2] = 3;
        cronModel.setDayOfWeeks(dayOfWeeks);
        cronModel.setJobType(JobEnum.WEEK);
        cropExp = createCronExpression(cronModel);
        System.out.println(cropExp + ":" + createDescription(cronModel));
        System.out.println(getCronNextTimes(cropExp, 5));

        cronModel.setJobType(JobEnum.MONTH);//每月的哪几天执行
        Integer[] dayOfMonths = new Integer[3];
        dayOfMonths[0] = 1;
        dayOfMonths[1] = 21;
        dayOfMonths[2] = 13;
        cronModel.setDayOfMonths(dayOfMonths);
        cropExp = createCronExpression(cronModel);
        System.out.println(cropExp + ":" + createDescription(cronModel));
        System.out.println(getCronNextTimes(cropExp, 5));

        cronModel.setJobType(JobEnum.EVERY);//每天的几点几分几秒开始
        cropExp = createCronExpression(cronModel);
        System.out.println(cropExp);
        System.out.println(getCronNextTimes(cropExp, 5));

    }

}