How to spring inject configuration value for Joda Period

Question

How can I use the @Value annotation to configure a Joda-Time Period field in my spring bean?

E.g. Given the following component class:

@Component
public class MyService {

  @Value("${myapp.period:P1D}")
  private Period periodField;
...
}

I want to use standard ISO8601 format to define the period in a properties file.

I get this error:

Caused by: java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [org.joda.time.Period]: no matching editors or conversion strategy found
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:302)
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:125)
    at org.springframework.beans.TypeConverterSupport.doConvert(TypeConverterSupport.java:61)
    ... 35 more

Answer 1

A simple solution that does not require any java code is to use Spring Expression Language (SpEL).

(My example uses java.time.Duration and not Joda stuff but I think you get it anyway.)

    @Value("#{T(java.time.Duration).parse('${notifications.maxJobAge}')}")
    private Duration maxJobAge;

Answer 2

What you can do is register a Spring ConversionService bean and implement a proper converter.

@Bean
public ConversionServiceFactoryBean conversionService() {
    ConversionServiceFactoryBean conversionServiceFactoryBean = new ConversionServiceFactoryBean();
    Set<Converter<?, ?>> myConverters = new HashSet<>();
    myConverters.add(new StringToPeriodConverter());
    conversionServiceFactoryBean.setConverters(myConverters);
    return conversionServiceFactoryBean;
}

public class StringToPeriodConverter implements Converter<String, Period> {

    @Override
    public Period convert(String source) {
        return Period.parse(source);
    }
}

Answer 3

Another, not elegant, option, is to use a String setter who invokes the parse method.

@Value("${myapp.period:P1D}")
public void setPeriodField(String periodField)
{
    if (isBlank(periodField))
        this.periodField= null;
    this.periodField= Duration.parse(periodField);
}