如何使用 java config 而不是 XML 声明一个存储库填充器 bean?

问题描述

我正在开发一个基于 Spring 的项目，该项目(到目前为止)完全没有 XML，但现在我在 Spring JPA 存储库填充器上遇到了困难:

I am working on a Spring based project that is (so-far) completely XML-free, except now I've hit a wall with the Spring JPA repository populator:

<repository:jackson-populator location="classpath:data.json" />

如何在 java @Configuration 类中表达以上内容?

How would the above be expressed in a java @Configuration class?

这篇文章建议直接使用 FactoryBean:https://stackoverflow.com/a/13566712/1746274

This post suggests using the FactoryBean directly: https://stackoverflow.com/a/13566712/1746274

我试过了，我得到的最接近的是以下，但它不太正确.

I tried that and the closest I got was the following but it's not quite right.

@Bean(name="repositoryPopulator")
public RepositoryPopulator getRespositoryPopulator() throws Exception {
    final JacksonRepositoryPopulatorFactoryBean factory =  new JacksonRepositoryPopulatorFactoryBean();
    factory.getObject().setResourceLocation("classpath:test-data.json");
    factory.afterPropertiesSet();
    return factory.getObject();
}

上述结果导致 FactoryBeanNotInitializedException 消息 JacksonRepositoryPopulatorFactoryBean 不支持循环引用.

The above results in a FactoryBeanNotInitializedException with the message JacksonRepositoryPopulatorFactoryBean does not support circular references.

有什么想法吗?

推荐答案

其实很简单:

@Configuration
class ApplicationConfig {

  @Bean
  public JacksonRepositoryPopulatorFactoryBean repositoryPopulator() {

    Resource sourceData = new ClassPathResource("test-data.json");

    JacksonRepositoryPopulatorFactoryBean factory = new JacksonRepositoryPopulatorFactoryBean();
    // Set a custom ObjectMapper if Jackson customization is needed
    factory.setObjectMapper(…);
    factory.setResources(new Resource[] { sourceData });
    return factory;
  }
}

通过返回 FactoryBean 本身，Spring 将负责调用所有必要的回调接口(即 setApplicationContext(…)、setBeanClassLoader(…)等).工厂 bean 是一个 ApplicationListener，因此将在 ApplicationContext 完全初始化时侦听 ContextRefreshedEvent 并触发填充.