如何在springboot中在ConversionService中自动接线
问题内容：
尝试在springboot中访问模型中的ConversionControl，不走运。
@Component
public class CityHelperService {
@Autowired
ConversionService conversionService;// = ConversionServiceFactory.registerConverters();
public City toEntity(CityDTO dto){
City entity = conversionService.convert(dto, City.class);
return entity;
}
public CityDTO toDTO(City entity){
CityDTO dto = conversionService.convert(entity, CityDTO.class);
return dto;
}
}
它显示以下错误：
Injection of autowired dependencies failed;
nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.lumiin.mytalk.model.CityModel com.lumiin.mytalk.controllers.CityController.cityModel;
nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'cityModel' defined in file : Unsatisfied dependency expressed through constructor argument with index 1 of type [com.lumiin.mytalk.dao.CityHelperService]: : Error creating bean with name 'cityHelperService': Injection of autowired dependencies failed;
nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: org.springframework.core.convert.ConversionService com.lumiin.mytalk.dao.CityHelperService.conversionService;
nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.core.convert.ConversionService] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)};
nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'cityHelperService': Injection of autowired dependencies failed;
nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: org.springframework.core.convert.ConversionService com.lumiin.mytalk.dao.CityHelperService.conversionService;
nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.core.convert.ConversionService] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
问题答案：
ConversionService根据最后一个嵌套异常，显然没有bean可用：
org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.core.convert.ConversionService] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency.
通过查看Spring文档可以发现，您应该声明一个ConversionServicebean。在XML配置中，它看起来像这样：
<bean id="conversionService" class="org.springframework.context.support.ConversionServiceFactoryBean">
<property name="converters">
<set>
<bean class="example.MyCustomConverter"/>
</set>
</property>
</bean>
并且由于您使用的是Spring
Boot，所以我假设您是以编程方式创建上下文的，因此您应该创建一个带有注释的方法@Bean，该方法返回一个ConverstionService。
@Bean(name="conversionService")
public ConversionService getConversionService() {
ConversionServiceFactoryBean bean = new ConversionServiceFactoryBean();
bean.setConverters(...); //add converters
bean.afterPropertiesSet();
return bean.getObject();
}
