Package org.drools.core.time.impl

Class KieCronExpression

  • All Implemented Interfaces:
    java.io.Serializable
    Direct Known Subclasses:
    CronExpression
    public class KieCronExpression
extends java.lang.Object
implements java.io.Serializable
    Provides a parser and evaluator for unix-like cron expressions. Cron expressions provide the ability to specify complex time combinations such as "At 8:00am every Monday through Friday" or "At 1:30am every last Friday of the month".

    Cron expressions are comprised of 6 required fields and one optional field separated by white space. The fields respectively are described as follows:

    Field Name   Allowed Values   Allowed Special Characters
    Seconds   0-59   , - * /
    Minutes   0-59   , - * /
    Hours   0-23   , - * /
    Day-of-month   1-31   , - * ? / L W
    Month   1-12 or JAN-DEC   , - * /
    Day-of-Week   1-7 or SUN-SAT   , - * ? / L #
    Year (Optional)   empty, 1970-2199   , - * /

    The '*' character is used to specify all values. For example, "*" in the minute field means "every minute".

    The '?' character is allowed for the day-of-month and day-of-week fields. It is used to specify 'no specific value'. This is useful when you need to specify something in one of the two fields, but not the other.

    The '-' character is used to specify ranges For example "10-12" in the hour field means "the hours 10, 11 and 12".

    The ',' character is used to specify additional values. For example "MON,WED,FRI" in the day-of-week field means "the days Monday, Wednesday, and Friday".

    The '/' character is used to specify increments. For example "0/15" in the seconds field means "the seconds 0, 15, 30, and 45". And "5/15" in the seconds field means "the seconds 5, 20, 35, and 50". Specifying '*' before the '/' is equivalent to specifying 0 is the value to start with. Essentially, for each field in the expression, there is a set of numbers that can be turned on or off. For seconds and minutes, the numbers range from 0 to 59. For hours 0 to 23, for days of the month 0 to 31, and for months 1 to 12. The "/" character simply helps you turn on every "nth" value in the given set. Thus "7/6" in the month field only turns on month "7", it does NOT mean every 6th month, please note that subtlety.

    The 'L' character is allowed for the day-of-month and day-of-week fields. This character is short-hand for "last", but it has different meaning in each of the two fields. For example, the value "L" in the day-of-month field means "the last day of the month" - day 31 for January, day 28 for February on non-leap years. If used in the day-of-week field by itself, it simply means "7" or "SAT". But if used in the day-of-week field after another value, it means "the last xxx day of the month" - for example "6L" means "the last friday of the month". When using the 'L' option, it is important not to specify lists, or ranges of values, as you'll get confusing results.

    The 'W' character is allowed for the day-of-month field. This character is used to specify the weekday (Monday-Friday) nearest the given day. As an example, if you were to specify "15W" as the value for the day-of-month field, the meaning is: "the nearest weekday to the 15th of the month". So if the 15th is a Saturday, the trigger will fire on Friday the 14th. If the 15th is a Sunday, the trigger will fire on Monday the 16th. If the 15th is a Tuesday, then it will fire on Tuesday the 15th. However if you specify "1W" as the value for day-of-month, and the 1st is a Saturday, the trigger will fire on Monday the 3rd, as it will not 'jump' over the boundary of a month's days. The 'W' character can only be specified when the day-of-month is a single day, not a range or list of days.

    The 'L' and 'W' characters can also be combined for the day-of-month expression to yield 'LW', which translates to "last weekday of the month".

    The '#' character is allowed for the day-of-week field. This character is used to specify "the nth" XXX day of the month. For example, the value of "6#3" in the day-of-week field means the third Friday of the month (day 6 = Friday and "#3" = the 3rd one in the month). Other examples: "2#1" = the first Monday of the month and "4#5" = the fifth Wednesday of the month. Note that if you specify "#5" and there is not 5 of the given day-of-week in the month, then no firing will occur that month. If the '#' character is used, there can only be one expression in the day-of-week field ("3#1,6#3" is not valid, since there are two expressions).

    The legal characters and the names of months and days of the week are not case sensitive.

    NOTES:

    • Support for specifying both a day-of-week and a day-of-month value is not complete (you'll need to use the '?' character in one of these fields).
    • Overflowing ranges is supported - that is, having a larger number on the left hand side than the right. You might do 22-2 to catch 10 o'clock at night until 2 o'clock in the morning, or you might have NOV-FEB. It is very important to note that overuse of overflowing ranges creates ranges that don't make sense and no effort has been made to determine which interpretation CronExpression chooses. An example would be "0 0 14-6 ? * FRI-MON".

    See Also:
    Serialized Form

    • Field Detail

      • YEAR_TO_GIVEUP_SCHEDULING_AT

        protected static final int YEAR_TO_GIVEUP_SCHEDULING_AT
        See Also:
        Constant Field Values

      • ALL_SPEC

        protected static final java.lang.Integer ALL_SPEC

      • NO_SPEC

        protected static final java.lang.Integer NO_SPEC

      • monthMap

        protected static final java.util.Map<java.lang.String,​java.lang.Integer> monthMap

      • dayMap

        protected static final java.util.Map<java.lang.String,​java.lang.Integer> dayMap

      • cronExpression

        protected java.lang.String cronExpression

      • seconds

        protected transient java.util.TreeSet seconds

      • minutes

        protected transient java.util.TreeSet minutes

      • hours

        protected transient java.util.TreeSet hours

      • daysOfMonth

        protected transient java.util.TreeSet daysOfMonth

      • months

        protected transient java.util.TreeSet months

      • daysOfWeek

        protected transient java.util.TreeSet daysOfWeek

      • years

        protected transient java.util.TreeSet years

      • lastdayOfWeek

        protected transient boolean lastdayOfWeek

      • nthdayOfWeek

        protected transient int nthdayOfWeek

      • lastdayOfMonth

        protected transient boolean lastdayOfMonth

      • nearestWeekday

        protected transient boolean nearestWeekday

      • expressionParsed

        protected transient boolean expressionParsed

    • Constructor Detail

      • KieCronExpression

        public KieCronExpression​(java.lang.String cronExpression)
                  throws java.text.ParseException
        Constructs a new CronExpression based on the specified parameter.
        Parameters:
        cronExpression - String representation of the cron expression the new object should represent
        Throws:
        java.text.ParseException - if the string expression cannot be parsed into a valid CronExpression

    • Method Detail

      • toString

        public java.lang.String toString()
        Returns the string representation of the CronExpression
        Overrides:
        toString in class java.lang.Object
        Returns:
        a string representation of the CronExpression

      • isValidExpression

        public static boolean isValidExpression​(java.lang.String cronExpression)
        Indicates whether the specified cron expression can be parsed into a valid cron expression
        Parameters:
        cronExpression - the expression to evaluate
        Returns:
        a boolean indicating whether the given expression is a valid cron expression

      • buildExpression

        protected void buildExpression​(java.lang.String expression)
                        throws java.text.ParseException
        Throws:
        java.text.ParseException

      • storeExpressionVals

        protected int storeExpressionVals​(int pos,
                                  java.lang.String s,
                                  int type)
                           throws java.text.ParseException
        Throws:
        java.text.ParseException

      • checkNext

        protected int checkNext​(int pos,
                        java.lang.String s,
                        int val,
                        int type)
                 throws java.text.ParseException
        Throws:
        java.text.ParseException

      • getCronExpression

        public java.lang.String getCronExpression()

      • getExpressionSummary

        public java.lang.String getExpressionSummary()

      • getExpressionSetSummary

        protected java.lang.String getExpressionSetSummary​(java.util.Set set)

      • getExpressionSetSummary

        protected java.lang.String getExpressionSetSummary​(java.util.ArrayList list)

      • skipWhiteSpace

        protected int skipWhiteSpace​(int i,
                             java.lang.String s)

      • findNextWhiteSpace

        protected int findNextWhiteSpace​(int i,
                                 java.lang.String s)

      • addToSet

        protected void addToSet​(int val,
                        int end,
                        int incr,
                        int type)
                 throws java.text.ParseException
        Throws:
        java.text.ParseException

      • getSet

        protected java.util.TreeSet getSet​(int type)

      • getNumericValue

        protected int getNumericValue​(java.lang.String s,
                              int i)

      • getMonthNumber

        protected int getMonthNumber​(java.lang.String s)

      • getDayOfWeekNumber

        protected int getDayOfWeekNumber​(java.lang.String s)