java - 如何在 spring-boot 中强制 Jackson2ObjectMapperBuilder？

Question

我想创建自己的 jackson ObjectMapper bean，如下所示:

@SpringBootApplication
@AutoConfigureBefore(JacksonAutoConfiguration.class) //even this does not help
public class MyConfig extends SpringBootServletInitializer {
    @Bean
    @Primary
    public ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {
        return builder.createXmlMapper(true).build(); //much more configurations
    }
}

问题:bean 从未创建，而是执行默认的 JacksonAutoConfiguration:

package org.springframework.boot.autoconfigure.jackson;

@Configuration
@ConditionalOnClass(ObjectMapper.class)
public class JacksonAutoConfiguration {
        @Bean
        @Primary
        @ConditionalOnMissingBean(ObjectMapper.class)
        public ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {
            return builder.createXmlMapper(false).build(); //this is always executed!
        }
}

因此，当评估 JacksonAutoConfiguration 时，ObjectMapper bean 还不存在。但为什么呢？

通过使用断点进行调试，我还可以看到我的 bean 从未被调用!但我注意到:即使我有@AutoConfigureBefore，jackson autoconfig仍然在MyConfig中的任何bean之前运行。奇怪吗？

Answer 1

Here's Spring关于定制ObjectMapper的文档，是这样说的:

If you want to replace the default ObjectMapper completely, either define a @Bean of that type and mark it as @Primary, or, if you prefer the builder-based approach, define a Jackson2ObjectMapperBuilder @Bean. Note that in either case this will disable all auto-configuration of the ObjectMapper.

如果定义 ObjectMapper bean 没有帮助，您可以尝试定义 Jackson2ObjectMapperBuilder bean 吗？

另外，您可以尝试将 bean 定义到用 @Configuration 注释的类中吗？