使用ConversionServiceFactoryBean或GenericConversionService注册自定义转换器？

Question

@Bean
public ConversionService conversionService(
        Set<Converter<?, ?>> converters,
        ConversionServiceFactoryBean factory) {
    factory.setConverters(converters);
    return factory.getObject();
}

@Bean
public ConversionServiceFactoryBean conversionServiceFactoryBean() {
    return new ConversionServiceFactoryBean();
}

<bean id="conversionService"
        class="org.springframework.context.support.ConversionServiceFactoryBean">
    <property name="converters">
        <set>
            <bean class="example.MyCustomConverter"/>
        </set>
    </property>
</bean>

ConverterNotFoundException: No converter found capable of converting from type [java.lang.String] to type [java.time.Duration]

@Bean
public ConversionService conversionService(Set<Converter<?, ?>> converters) {
    final GenericConversionService conversionService = new GenericConversionService();
    converters.forEach(conversionService::addConverter);
    return conversionService;
}

为什么它不能与ConversionServiceFactoryBean和Java配置一起工作？为什么它与GenericConversionService一起使用？

Answer 1

这是因为您试图在初始化ConversionServiceFactoryBeanbean之后，将转换器注册到ConversionService方法中，即在构造工厂bean时已经调用了AfterPropertiesSet。如果要使用问题中的第一个方法，则需要在调用afterPropertiesSet方法之前注册转换器。因此，我将按以下方式更改ConversionService和ConversionServiceFactoryBean方法；

@Bean
public ConversionService conversionService(ConversionServiceFactoryBean factory) {
    return factory.getObject();
}

@Bean
public ConversionServiceFactoryBean conversionServiceFactoryBean(Set<Converter<?, ?>> converters) {
    ConversionServiceFactoryBean factory = new ConversionServiceFactoryBean();
    factory.setConverters(converters);
    return factory;
}

但是，分离这两个方法没有任何意义，因为ConversionService的实例已经在spring上下文中注册了。因此，最好将这两种方法合并如下；

注方法名从ConversionServiceFactoryBean更改为ConversionService。如果没有名称更改，Spring将抛出一个异常，无法按预期转换数据。

@Bean
public ConversionServiceFactoryBean conversionService(Set<Converter<?, ?>> converters) {
    ConversionServiceFactoryBean factory = new ConversionServiceFactoryBean();
    factory.setConverters(converters);
    return factory;
}