如何为Joda Period注入配置值

Question

如何使用@Value注释在我的spring bean中配置Joda-Time Period字段？

例如,给定以下组件类:

@Component
public class MyService {

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

我想使用标准的ISO8601格式来定义属性文件中的句点.

我收到此错误:

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

一个不需要任何java代码的简单解决方案是使用Spring Expression Language(SpEL).

(我的例子使用的是java.time.Duration,而不是Joda的东西,但我认为无论如何你都会得到它.)

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

Answer 2

您可以做的是注册一个 SpringConversionService bean 并实现一个适当的转换器。

@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);
    }
}