RFC5545。同时计算RRULE和EXDATE (EXRULE)的事件发生情况
我必须计算事件的发生情况。计算应基于反复发生的事件模式。递归事件模式是基于rfc5545的。
我已经找到了利伯-罗瑟库来计算出现的情况。在下面的描述中，我看到它们使用特定实例集的实例(例如，rrule、exrule、rdate或exdate的列表)来提供计算。我为RRULE使用了计算，看起来很有效。我需要在我的逻辑找到正确的所有事件，包括在计算EXDATE，EXRULE。但似乎最后的排除条款在这里并不支持。小代码示例：
import org.dmfs.rfc5545.DateTime;
import org.dmfs.rfc5545.recurrenceset.RecurrenceRuleAdapter;
import org.dmfs.rfc5545.recurrenceset.RecurrenceSet;
import org.dmfs.rfc5545.recurrenceset.RecurrenceSetIterator;
@Test
public void testSpecial() throws InvalidRecurrenceRuleException {
RecurrenceRule recurrenceRule = new RecurrenceRule("FREQ=YEARLY;BYMONTHDAY=23;BYMONTH=5;COUNT=3");
RecurrenceRuleIterator it = recurrenceRule.iterator(DateTime.nowAndHere());
int maxInstances = 10; // limit instances for rules that recur forever
while (it.hasNext() && (!recurrenceRule.isInfinite() || maxInstances-- > 0)) {
DateTime nextInstance = it.nextDateTime();
// do something with nextInstance
System.out.println(nextInstance);
}
}结果：
20170714T163325 20180523T163325 20190523T163325
我也知道基于google的图书馆可以为RRULES，EXRULE提供核心处理程序。基于rfc5545标准。但是我还没有找到如何在这里计算事件(包括RRULES，EXDATE，EXRULE)。
更多的例子是google-rfc-2445库：
import com.google.ical.compat.jodatime.LocalDateIterable;
import com.google.ical.compat.jodatime.LocalDateIterator;
import com.google.ical.compat.jodatime.LocalDateIteratorFactory;
import com.google.ical.values.RRule;
@Test
public void test() throws ParseException {
String sRule = "RRULE:FREQ=YEARLY;COUNT=3;INTERVAL=2;BYMONTH=5;BYMONTHDAY=22,23,24,25,26,27,28;BYDAY=MO";
LocalDateIterable localDateIterable = LocalDateIteratorFactory
.createLocalDateIterable(sRule, org.joda.time.LocalDate.now(), true);
LocalDateIterator iterator = localDateIterable.iterator();
while (iterator.hasNext()) {
System.out.println(iterator.next());
}
}结果：
2017-07-14 2019-05-27 2021-05-24 2023-05-22
请共享到已经具有复杂发生计算功能的开源库的链接(计算应该同时包括RRULE、EXDATE)。
回答 1
Stack Overflow用户
发布于 2017-07-14 21:05:48
lib-recur确实支持计算递归集。不过，这个组件的接口还不完善(也不太方便)。
下面是一个简单的示例，说明如何使用一个RRULE和一个EXRULE：
// note: recurrence expansion takes place in a specific time zone
TimeZone tz = TimeZone.getDefault();
// the start of the recurring event
DateTime start = new DateTime(tz, 2017, 5 - 1 /* zero based */, 23, 12, 0, 0);
// parse the RRULE
RecurrenceRule recurrenceRule = new RecurrenceRule("FREQ=YEARLY;BYMONTHDAY=23;BYMONTH=5;COUNT=30");
// parse the EXRULE (in this case every 3rd instance of the RRULE)
RecurrenceRule exceptionRule = new RecurrenceRule("FREQ=YEARLY;INTERVAL=3;BYMONTHDAY=23;BYMONTH=5;COUNT=10");
// create an empty RecurrenceSet
// a recurrence set is the set of all actual instance of a recurring event and may consist of multiple instance and excludes sources
RecurrenceSet recurrenceSet = new RecurrenceSet();
// add the instances of the RRULE
recurrenceSet.addInstances(new RecurrenceRuleAdapter(recurrenceRule));
// exclude the instances of the EXRULE
recurrenceSet.addExceptions(new RecurrenceRuleAdapter(exceptionRule));
RecurrenceSetIterator recurrenceSetIterator = recurrenceSet.iterator(start.getTimeZone(), start.getTimestamp());
int maxInstances = 10; // limit instances for rules that recur forever
// iterate as long as the recurrence set still has instances
while (recurrenceSetIterator.hasNext() && (!recurrenceRule.isInfinite() || maxInstances-- > 0))
{
// get the next instance of the recurrence set
DateTime nextInstance = new DateTime(start.getTimeZone(), recurrenceSetIterator.next());
// do something with nextInstance
System.out.println(nextInstance);
}您可以看到，RecurrenceSet在long时间戳上运行，这是非常不理想的。
要支持RDATES和EXDATES，可以使用RecurrenceList适配器。RecurrenceList要么接受一个时间戳数组，要么接受一个时区和一个逗号分隔的日期-时间或日期值字符串(就像为RDATES和EXDATES定义的那样)：
// add more RDATES instances
recurrenceSet.addInstances(new RecurrenceList("20171212T121212,20181212T121212", tz));
// add EXDATES
recurrenceSet.addExceptions(new RecurrenceList("20180523T120000,20190523T120000", tz));注意，与RecurrenceRuleIterator不同的是，这个组件还没有任何测试覆盖率。
https://stackoverflow.com/questions/45101330
复制相似问题
腾讯云开发者
