在Spring WebFlux中修改/覆盖/扩展内置的Jackson 2 ObjectMapper的建议方法是什么？

Question

目前，我与Jackson libraries有一个极简的Spring/Netty、Reactor/Web Flux项目

@Configuration
public class EmbeddedSpringServer extends DelegatingWebFluxConfiguration {
    @Bean
    MyController controller() {
        return new AdminController();
    }
    public static void main(String[] args) throws Exception {
        AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(EmbeddedSpringServer.class);
        HttpHandler handler = WebHttpHandlerBuilder.applicationContext(applicationContext).build();
        ReactorHttpHandlerAdapter adapter = new ReactorHttpHandlerAdapter(handler);
        HttpServer.create("0.0.0.0", 8082).newHandler(adapter).subscribe();
        applicationContext.registerShutdownHook();
    }
}

        compile 'org.springframework:spring-context:5.0.2.RELEASE'
        compile 'org.springframework:spring-web:5.0.2.RELEASE'
        compile 'org.springframework:spring-webflux:5.0.2.RELEASE'
        compile 'io.projectreactor.ipc:reactor-netty:0.7.2.RELEASE'

        compile group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.9.3'

Controller类工作良好（它返回具有DTO类型的mono<>)。由于Jackson存在于类路径中，Web Flux通过DefaultServerCodeCconfigureer自动创建对象映射器实例，但不清楚如何覆盖对象映射器实例，因为大多数Web Flux配置类都是包专用的。

我希望实现的是创建自己的对象映射器，以添加在jackson-modules-java8中实现的自定义localdatetime序列化

ObjectMapper mapper = new ObjectMapper()
   .registerModule(new ParameterNamesModule())
   .registerModule(new Jdk8Module())
   .registerModule(new JavaTimeModule())
;

问题是，不清楚如何修改包privateorg.springframework.http.codec.support.abstractcodecconfigurer.abstractdefaultcodecs中创建的jackson2jsonencoder。

Answer 1

结果比我最初想象的要简单，因为DelegatingWebFluxConfiguration已经有一个ConfigureHttpMessageCodecs方法重写，这就足够了

@Configuration
public class EmbeddedSpringServer extends DelegatingWebFluxConfiguration {
    @Bean
    MyController controller() {
        return new MyController();
    }

    public static void main(String[] args) throws Exception {
        AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(EmbeddedSpringServer.class);
        HttpHandler handler = WebHttpHandlerBuilder.applicationContext(applicationContext).build();
        ReactorHttpHandlerAdapter adapter = new ReactorHttpHandlerAdapter(handler);
        HttpServer.create("0.0.0.0", 8082).newHandler(adapter).subscribe();
        applicationContext.registerShutdownHook();
    }

    @Bean
    ObjectMapper objectMapper(){
        return new ObjectMapper()
                .registerModule(new ParameterNamesModule())
                .registerModule(new Jdk8Module())
                .registerModule(new JavaTimeModule());

    }

    @Override
    protected void configureHttpMessageCodecs(ServerCodecConfigurer configurer) {
        configurer.defaultCodecs().jackson2JsonEncoder(new Jackson2JsonEncoder(objectMapper()));
        configurer.defaultCodecs().jackson2JsonDecoder(new Jackson2JsonDecoder(objectMapper()));
    }
}

至于Spring引导，我认为也可以通过返回WebFluxConfigureer bean来实现

@Bean
WebFluxConfigurer webFluxConfigurer(ObjectMapper objectMapper) {
        return new WebFluxConfigurer() {
            @Override
            public void configureHttpMessageCodecs(ServerCodecConfigurer configurer) {
                configurer.defaultCodecs().jackson2JsonEncoder(new Jackson2JsonEncoder(objectMapper());
                configurer.defaultCodecs().jackson2JsonDecoder(new Jackson2JsonDecoder(objectMapper());
            }
        };
    }

因为它们是由@enablewebflux自动创建的delegatingwebfluxconfiguration选择的。

请注意。Jackson2ObjectMapperBuilder的默认实现已经自动注册了这些日期模块。日期问题与此无关，我以

@Override
    protected void configureHttpMessageCodecs(ServerCodecConfigurer configurer) {
        configurer.defaultCodecs().jackson2JsonEncoder(new Jackson2JsonEncoder(Jackson2ObjectMapperBuilder
        .json()
          .featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
        .build()));
    } 

以实现简单的日期序列化。