SpringBoot 2.2.2：用于自定义分页的 Jackson 序列化程序不起作用

Posted 2023-02-27

【中文标题】SpringBoot 2.2.2：用于自定义分页的 Jackson 序列化程序不起作用

【英文标题】：SpringBoot 2.2.2: Jackson serializer for custom pagination doesn't work

【发布时间】：2020-04-11 11:17:06

【问题描述】：

从 SpringBoot 2.2.2 开始，带有 Jackson (2.10.1) 的自定义分页序列化程序不起作用，并且在序列化时不执行。

/**
 * This class allows to specify configuration related to the Web MVC part.
 */
@Configuration
public class WebConfiguration implements WebMvcConfigurer 

    private static final String JSON_DATA_PROPERTY = "data";

    /**
     * Allows to configure a @link JsonSerializer for pagination.
     *
     * @return an instance of @link Module.
     */
    @SuppressWarnings("rawtypes")
    @Bean
    public Module springDataPageModule() 
        return new SimpleModule().addSerializer(Page.class, new JsonSerializer<Page>() 
            @Override
            public void serialize(final Page page, final JsonGenerator jsonGenerator,
                    final SerializerProvider serializers) throws IOException 

                jsonGenerator.writeStartObject();
                jsonGenerator.writeObjectField(JSON_DATA_PROPERTY, page.getContent());
                jsonGenerator.writeObjectFieldStart("paging");
                jsonGenerator.writeNumberField("page", page.getNumber() + 1);
                jsonGenerator.writeNumberField("totalPages", page.getTotalPages());
                jsonGenerator.writeNumberField("totalElements", page.getTotalElements());
                jsonGenerator.writeNumberField("perPage", page.getSize());
                jsonGenerator.writeEndObject();
                jsonGenerator.writeEndObject();
            
        );
    
...

在 SpringBoot 2.2.1 中，这个自定义分页序列化器被应用并工作。 你能看出这个问题吗？

【参考方案1】：

自 SpringBoot 2.2.2 以来，该行为发生了变化。 您必须通过模块的注册

/**
 * This class allows to specify configuration related to the Web MVC part.
 */
@Configuration
public class WebConfiguration implements WebMvcConfigurer 

    private static final String JSON_DATA_PROPERTY = "data";

    /**
     * Allows to configure a @link JsonSerializer for pagination.
     *
     * @return an instance of @link Module.
     */
    private Module preparePageModule() 
        return new SimpleModule().addSerializer(Page.class, new JsonSerializer<>() 
            @Override
            public void serialize(@SuppressWarnings("rawtypes") final Page page, final JsonGenerator jsonGenerator,
                    final SerializerProvider serializers) throws IOException 

                jsonGenerator.writeStartObject();
                jsonGenerator.writeObjectField(JSON_DATA_PROPERTY, page.getContent());
                jsonGenerator.writeObjectFieldStart("paging");
                jsonGenerator.writeNumberField("page", page.getNumber() + 1);
                jsonGenerator.writeNumberField("totalPages", page.getTotalPages());
                jsonGenerator.writeNumberField("totalElements", page.getTotalElements());
                jsonGenerator.writeNumberField("perPage", page.getSize());
                jsonGenerator.writeEndObject();
                jsonGenerator.writeEndObject();
            
        );
    

    /**
     * Allows to configure the Jackson object mapper.
     *
     * @param objectMapper
     *            an instance of @link ObjectMapper.
     */
    @Autowired
    public void configureJacksonObjectMapper(final ObjectMapper objectMapper) 
        ...
        objectMapper.registerModule(preparePageModule());
    
...

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