为什么正确使用ical4j时会收到ValidationException？

Question

我尝试使用ical4j构建日历。当我尝试将输出输出到文件时，它给了我如下所示的异常：

net.fortuna.ical4j.validate.ValidationException: Property [PRODID] must be specified once.

代码：

FileOutputStream icsOutputStream = new FileOutputStream(new File("").getAbsoluteFile()+ "classInfo.ics");
CalendarOutputter icsOutputter = new CalendarOutputter();
icsOutputter.output(ical4jHandler.icsCalender,icsOutputStream);

Answer 1

在ical4j documentation中，您可以尝试以下操作：

import net.fortuna.ical4j.model.Calendar;

// add this :
// create a new calendar
Calendar cal = new Calendar();
cal.getProperties().add(new ProdId("-//Ben Fortuna//iCal4j 1.0//EN"));
cal.getProperties().add(Version.VERSION_2_0);
// set other properties by looking at the documentation..

// your code 
FileOutputStream icsOutputStream = new FileOutputStream(new File("").getAbsoluteFile()+ "classInfo.ics");
CalendarOutputter icsOutputter = new CalendarOutputter();
// send the cal reference directly.
icsOutputter.output(cal,icsOutputStream);

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