在 Spring @Value('#{SPEL}) 中使用 Java 类

Question

I would like to parse the property value into an custom Object. Example; i have application.properties; say

rules.peakHours.weekday.morning.start=10:15:45

And would like to convert that property into java LocalTime object.

@Configuration
public class RuleUtils {


    @Value("#{localTime.parse(\"${rules.peakHours.weekday.morning.start}\")}")
    public LocalTime weekDayMorningPeakStart;

I have tried the below, but not helping.

    @Bean
    @ConfigurationProperties("localTime")
//    @EnableConfigurationProperties(LocalTime.class)
    public Class<LocalTime> getLocalTime() {

        return LocalTime.class;
    }

Getting below error:

 EL1008E: Property or field 'localTime' cannot be found on object of type 'org.springframework.beans.factory.config.BeanExpressionContext'

I tried web and stackoverflow, but not getting specific answer. Please help.

Only workaround i know for this is constructor injection; but this will bloat my constructor with many arguments

@Configuration
public class RuleUtils {

    public LocalTime weekDayMorningPeakStart;

    public RuleUtils(@Value("${rules.peakHours.weekday.morning.start}") String weekDayMorningPeakStart) {
         this.weekDayMorningPeakStart = LocalTime.parse(weekDayMorningPeakStart);
    }

Answer 1

You can use expression templating to parse into LocalTime, like show in docs

@Value("#{ T(java.time.LocalTime).parse('${rules.peakHours.weekday.morning.start}')}")
private LocalTime localTime;