How to format java.time.LocalDateTime and java.time.LocalDate with pattern?

问题

In the following snipped the property $F is of class java.time.LocalDateTime or java.time.LocalDate.

<textField pattern="EE. dd.MM.yyyy">
    <reportElement...>
    </reportElement>
    <textFieldExpression><![CDATA[$F{theLocalDateTime}]]></textFieldExpression>
</textField>

How can I format this property with textField pattern in jasper reports?

回答1:

To use the pattern attribute in current version of jasper-report for Date/Time object you need a java.util.Date class or one of it's subclasses.

The solution is to convert java.time.LocalDate and java.time.LocalDateTime

Converting to java.util.Date

from java.time.LocalDate

<textField pattern="EE. dd.MM.yyyy">
    <reportElement...>
    </reportElement>
    <textFieldExpression><![CDATA[java.util.Date.from($F{theLocalDate}.atStartOfDay(java.time.ZoneId.systemDefault()).toInstant())]]></textFieldExpression>
</textField>

from java.time.LocalDateTime

<textField pattern="EE. dd.MM.yyyy">
    <reportElement...>
    </reportElement>
    <textFieldExpression><![CDATA[java.util.Date.from($F{theLocalDateTime}.atZone(java.time.ZoneId.systemDefault()).toInstant())]]></textFieldExpression>
</textField>

Converting to java.sql.Timestamp

from java.time.LocalDate

<textField pattern="EE. dd.MM.yyyy">
    <reportElement...>
    </reportElement>
    <textFieldExpression><![CDATA[java.sql.Timestamp.valueOf($F{theLocalDate}.atStartOfDay())]]></textFieldExpression>
</textField>

from java.time.LocalDateTime

<textField pattern="EE. dd.MM.yyyy">
    <reportElement...>
    </reportElement>
    <textFieldExpression><![CDATA[java.sql.Timestamp.valueOf($F{theLocalDateTime})]]></textFieldExpression>
</textField>

Note: Applying pattern is always preferable solution, specially when exporting to excel since correct class will be passed to poi (hence excel will recognize column as a date and apply same formatting as in pattern)

来源：https://stackoverflow.com/questions/38830722/how-to-format-java-time-localdatetime-and-java-time-localdate-with-pattern