如何在弹簧靴中注册自定义转换器？ [英] How to register custom converters in spring boot?

问题描述

我使用spring-boot-starter-jdbc（v1.3.0）编写应用程序。

I writing application using spring-boot-starter-jdbc (v1.3.0).

我遇到的问题： BeanPropertyRowMapper 的实例失败，因为它无法从 java转换.sql.Timestamp 到 java.time.LocalDateTime 。

The problem that I met: Instance of BeanPropertyRowMapper fails as it cannot convert from java.sql.Timestamp to java.time.LocalDateTime.

为了复制这个问题，我实现了
org.springframework.core.convert.converter.Converter 对于这些类型。

In order to copy this problem, I implemented org.springframework.core.convert.converter.Converter for these types.

public class TimeStampToLocalDateTimeConverter implements Converter<Timestamp, LocalDateTime> {

    @Override
    public LocalDateTime convert(Timestamp s) {
        return s.toLocalDateTime();
    }
}

我的问题是：我如何提供 TimeStampToLocalDateTimeConverter for BeanPropertyRowMapper 。

My question is: How do I make available TimeStampToLocalDateTimeConverter for BeanPropertyRowMapper.

更一般的问题，我该怎么办？注册我的转换器，以使它们在系统范围内可用？

More general question, how do I register my converters, in order to make them available system wide?

以下代码在初始化阶段将我们带到 NullPointerException ：

The following code bring us to NullPointerException on initialization stage:

private Set<Converter> getConverters() {
    Set<Converter> converters = new HashSet<Converter>();
    converters.add(new TimeStampToLocalDateTimeConverter());
    converters.add(new LocalDateTimeToTimestampConverter());

    return converters;
}

@Bean(name="conversionService")
public ConversionService getConversionService() {
    ConversionServiceFactoryBean bean = new ConversionServiceFactoryBean();
    bean.setConverters(getConverters()); 
    bean.afterPropertiesSet();
    return bean.getObject();
}    

谢谢。

推荐答案

我建议使用@Autowired和spring的相关依赖注入机制在整个应用程序中使用单个ConversionService实例。 ConversionService将在配置中实例化。

I suggest to use @Autowired and the related dependency injection mechanism of spring to use a single ConversionService instance throughout your application. The ConversionService will be instantiated within the configuration.

所有应用程序范围内可用的转换器都会收到注释（例如@AutoRegistered）。在应用程序启动@Component FormatterRegistrar（类型名称本身有点误导，是的，它是...注册器，因为它进行注册。而@Component因为它是完全弹簧管理并需要依赖注入）将接收@AutoRegistered列表所有带注释的转换器。

All Converters to be available application wide receive an annotation (e.g. @AutoRegistered). On application start a @Component FormatterRegistrar (Type name itself is a bit misleading, yes it is "...Registrar" as it does the registering. And @Component as it is fully spring managed and requires dependency injection) will receive @AutoRegistered List of all annotated Converters.

请参阅此主题以获取具体实施细节。我们在项目中使用这种机制，它就像一个魅力。

See this thread for concrete implementation details. We use this mechanism within our project and it works out like a charm.

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