【Java 开发工具】Java实现程序生成 Cron表达式

废话不多说系列，直接开整 ~ 下面是次工具类的常用的核心接口：

1. 提供 【按每分钟】执行接口；
2. 提供 【按每天某时某分某秒】 执行接口；
3. 提供【每周周几某时某分某秒】执行接口；
4. 提供【每月某几号某时某分某秒】执行接口；

（1）引入 maven 依赖

<!--Lombok-->
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
</dependency>

（2）cron 表达式封装VO

import lombok.Getter;
import lombok.Setter;
import lombok.experimental.Accessors;

/**
 * cron 表达体
 *
 * @author zero
 * @create 2021-03-24 11:38
 */
@Getter
@Setter
@Accessors(chain = true)
public class TaskScheduleModel {
    /**
     * 所选作业类型:
     * 1  -> 每天
     * 2  -> 每月
     * 3  -> 每周
     */
    Integer jobType;

    /**
     * 一周的哪几天
     */
    Integer[] dayOfWeeks;

    /**
     * 一个月的哪几天
     */
    Integer[] dayOfMonths;

    /**
     * 秒
     */
    Integer second;

    /**
     * 分
     */
    Integer minute;

    /**
     * 时
     */
    Integer hour;

}

（3）CronUtils.java

/**
 * @author zero
 * @create 2021-03-24 11:37
 */
public class CronUtils {
    /**
     * 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()) {
            //执行周期未配置
            System.out.println("执行周期未配置");
        }
        if (null != taskScheduleModel.getSecond() && null == taskScheduleModel.getMinute() && null == taskScheduleModel.getHour()) {
            //每隔几秒
            if (taskScheduleModel.getJobType().intValue() == 0) {
                cronExp.append("0/").append(taskScheduleModel.getSecond());
                cronExp.append(" ");
                cronExp.append("* ");
                cronExp.append("* ");
                cronExp.append("* ");
                cronExp.append("* ");
                cronExp.append("?");
            }
        }
        if (null != taskScheduleModel.getSecond() && null != taskScheduleModel.getMinute() && null == taskScheduleModel.getHour()) {
            //每隔几分钟
            if (taskScheduleModel.getJobType().intValue() == 4) {
                cronExp.append("* ");
                cronExp.append("0/").append(taskScheduleModel.getMinute());
                cronExp.append(" ");
                cronExp.append("* ");
                cronExp.append("* ");
                cronExp.append("* ");
                cronExp.append("?");
            }
        }
        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) {
                //日
                cronExp.append("* ");
                //月
                cronExp.append("* ");
                //周
                cronExp.append("?");
            }
            //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 {
            //时或分或秒参数未配置
            System.out.println("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 任务模型数据
     * @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
     *
     * @param args
     */
    public static void main(String[] args) {
        //执行时间：每天的12时12分12秒 start
        TaskScheduleModel taskScheduleModel = new TaskScheduleModel();

        //按每秒
        taskScheduleModel.setJobType(0);
        taskScheduleModel.setSecond(30);
        String cronExp = createCronExpression(taskScheduleModel);
        System.out.println("按每秒：" + cronExp);

        //按每分钟
        taskScheduleModel.setJobType(4);
        taskScheduleModel.setMinute(8);
        String cronExpression = createCronExpression(taskScheduleModel);
        System.out.println("按每分钟：" + cronExpression);

        //按每天
        taskScheduleModel.setJobType(1);
        Integer hour = 12, minute = 12, second = 12;
        taskScheduleModel.setHour(hour);
        taskScheduleModel.setMinute(minute);
        taskScheduleModel.setSecond(second);
        String cropExp = createCronExpression(taskScheduleModel);
        //执行时间：每天的12时12分12秒 end
        System.out.println(cropExp + "\t--->>>\t" + createDescription(taskScheduleModel));

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

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

}

（4）测试示例

至此，感谢阅读🙏！