Groovy枚举中的计算值

Question

我需要创建一个具有一些预定义值的枚举或类,并且必须有一个选项来计算其他值.假设我们有这个枚举:

enum Duration {

    ONE_HOUR("1${DurationUnits.DURATION_SUFFIX_HOUR}"),
    ONE_DAY("24${DurationUnits.DURATION_SUFFIX_HOUR}"),
    ONE_WEEK("7${DurationUnits.DURATION_SUFFIX_DAY}"),
    ONE_MONTH("30${DurationUnits.DURATION_SUFFIX_DAY}")

    String duration

    Environment(String duration) {
        this.duration = duration
    }

    static String custom(Date startTime, Date endTime) {
        // TODO Calculate difference in days between the two dates  
    }

    private static class DurationUnits {
        public static final String DURATION_SUFFIX_HOUR = "h"
        public static final String DURATION_SUFFIX_DAY = "d"
    }

}

所以我的问题是,我是否可以定义一个枚举值,比如CUSTOM代表所有非预定义值的值.也就是说,该custom(Date a, Date b)方法的通用值.我无法弄清楚如何去做,实际上我认为它甚至不可能.

作为替代方案,我正在考虑创建一个类而不是枚举,如下所示:

class Duration {

    private static final String DURATION_SUFFIX_HOUR = "h"
    private static final String DURATION_SUFFIX_DAY = "d"

    /** Predefined values */

    static final String ONE_HOUR = "1${DURATION_SUFFIX_HOUR}"
    static final String ONE_DAY = "24${DURATION_SUFFIX_HOUR}"
    static final String ONE_WEEK = "7${DURATION_SUFFIX_DAY}"
    static final String ONE_MONTH = "30${DURATION_SUFFIX_DAY}"

    static String custom(Date startDate, Date endDate) {
        // TODO Calculate difference in days between the two dates
    }

}

您认为最好的方法是什么？此持续时间将是调用REST Web服务的方法的输入参数,这就是我尝试将其定义为枚举而不是仅传递字符串的原因.

Answer 1

您可以使用String append.

ONE_HOUR("1" + DurationUnits.DURATION_SUFFIX_HOUR),
ONE_DAY("24" + DurationUnits.DURATION_SUFFIX_HOUR),
ONE_WEEK("7" + DurationUnits.DURATION_SUFFIX_DAY),
ONE_MONTH("30" + DurationUnits.DURATION_SUFFIX_DAY);

但是,使用TimeUnits可能更好

ONE_HOUR(1, TimeUnit.HOUR),
ONE_DAY(1, TimeUnit.DAY),
ONE_WEEK(7, TimeUnit.DAY),
ONE_MONTH(30, TimeUnit.DAY);

注意:并非所有月份都有30天.

您还可以使用持续时间一段时间.

Duration ONE_HOUR = Duration.ofHours(1);
Duration ONE_DAY = Duration.ofDays(1);

这将允许您根据需要创建更多持续时间.