简述springboot web 自定义Jackson ObjectMapperBeanSerializerModifierimportcom.fasterxml.jackson.core.JsonGenerator;importcom.fasterxml.jackson.databind.BeanDescription;importcom.fasterxml.jackson.databind.JsonSerializer;importcom.fasterxml.jackson.databind.SerializationConfig;importcom.fasterxml.jackson.databind.SerializerProvider;importcom.fasterxml.jackson.databind.ser.BeanPropertyWriter;importcom.fasterxml.jackson.databind.ser.BeanSerializerModifier;importjava.io.IOException;importjava.time.LocalDateTime;importjava.util.Collection;importjava.util.Date;importjava.util.List;publicclassCustomNullSerializerModifierextendsBeanSerializerModifier{privatefinalStringNullSerializerstringNullSerializer;privatefinalArrayNullSerializerarrayNullSerializer;privatefinalDateNullSerializerdateNullSerializer;privatefinalNumberNullSerializernumberNullSerializer;publicCustomNullSerializerModifier(){this.stringNullSerializernewStringNullSerializer();this.arrayNullSerializernewArrayNullSerializer();this.dateNullSerializernewDateNullSerializer();this.numberNullSerializernewNumberNullSerializer();}OverridepublicListBeanPropertyWriterchangeProperties(SerializationConfigconfig,BeanDescriptionbeanDesc,ListBeanPropertyWriterbeanProperties){for(BeanPropertyWriterwriter:beanProperties){if(isString(writer)){writer.assignNullSerializer(this.stringNullSerializer);}elseif(isArrayType(writer)){writer.assignNullSerializer(this.arrayNullSerializer);}elseif(isNumberType(writer)){writer.assignNullSerializer(this.numberNullSerializer);}elseif(isDateType(writer)){writer.assignNullSerializer(this.dateNullSerializer);}elseif(isLocalDateTime(writer)){writer.assignNullSerializer(this.dateNullSerializer);}}returnbeanProperties;}booleanisString(BeanPropertyWriterwriter){returnwriter.getType().getRawClass().isAssignableFrom(String.class);}booleanisArrayType(BeanPropertyWriterwriter){returnwriter.getType().getRawClass().isArray()||writer.getType().getRawClass().isAssignableFrom(List.class)||writer.getType().getRawClass().isAssignableFrom(Collection.class);}booleanisNumberType(BeanPropertyWriterwriter){returnwriter.getType().getRawClass().isAssignableFrom(Integer.class)||writer.getType().getRawClass().isAssignableFrom(Long.class)||writer.getType().getRawClass().isAssignableFrom(Double.class);}booleanisDateType(BeanPropertyWriterwriter){returnwriter.getType().getRawClass().isAssignableFrom(Date.class);}booleanisLocalDateTime(BeanPropertyWriterwriter){returnwriter.getType().getRawClass().isAssignableFrom(LocalDateTime.class);}}classStringNullSerializerextendsJsonSerializerObject{Overridepublicvoidserialize(Objecto,JsonGeneratorjsonGenerator,SerializerProviderserializerProvider)throwsIOException{jsonGenerator.writeString();}}classArrayNullSerializerextendsJsonSerializerObject{Overridepublicvoidserialize(Objecto,JsonGeneratorjsonGenerator,SerializerProviderserializerProvider)throwsIOException{jsonGenerator.writeStartArray();jsonGenerator.writeEndArray();}}classDateNullSerializerextendsJsonSerializerObject{Overridepublicvoidserialize(Objecto,JsonGeneratorjsonGenerator,SerializerProviderserializerProvider)throwsIOException{jsonGenerator.writeNull();}}classNumberNullSerializerextendsJsonSerializerObject{Overridepublicvoidserialize(Objecto,JsonGeneratorjsonGenerator,SerializerProviderserializerProvider)throwsIOException{if(oinstanceofDouble){jsonGenerator.writeNumber(0.00);}elseif(oinstanceofFloat){jsonGenerator.writeNumber(0.00f);}else{jsonGenerator.writeNumber(0);}}}Object Mapperimportcom.fasterxml.jackson.annotation.JsonInclude;importcom.fasterxml.jackson.core.json.JsonReadFeature;importcom.fasterxml.jackson.databind.DeserializationFeature;importcom.fasterxml.jackson.databind.ObjectMapper;importcom.fasterxml.jackson.databind.SerializationFeature;importcom.fasterxml.jackson.datatype.jsr310.JavaTimeModule;importcom.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;importcom.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;importcom.fasterxml.jackson.datatype.jsr310.deser.LocalTimeDeserializer;importcom.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;importcom.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;importcom.fasterxml.jackson.datatype.jsr310.ser.LocalTimeSerializer;importcom.ft.mall.common.json.serializer.CustomNullSerializerModifier;importjava.text.SimpleDateFormat;importjava.time.LocalDate;importjava.time.LocalDateTime;importjava.time.LocalTime;importjava.time.ZoneId;importjava.time.format.DateTimeFormatter;importjava.util.TimeZone;publicclassCustomObjectMapperextendsObjectMapper{privatestaticfinalStringDATE_TIMEyyyy-MM-dd HH:mm:ss;privatestaticfinalStringDATEyyyy-MM-dd;privatestaticfinalStringTIMEHH:mm:ss;publicCustomObjectMapper(){super();registerModule();setSerializer();configure();this.setSerializerFactory(this.getSerializerFactory().withSerializerModifier(newCustomNullSerializerModifier()));}/* * LocalDateTime transfer */privatevoidregisterModule(){JavaTimeModulejavaTimeModulenewJavaTimeModule();javaTimeModule.addSerializer(LocalDateTime.class,newLocalDateTimeSerializer(DateTimeFormatter.ofPattern(DATE_TIME)));javaTimeModule.addDeserializer(LocalDateTime.class,newLocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DATE_TIME)));javaTimeModule.addSerializer(LocalDate.class,newLocalDateSerializer(DateTimeFormatter.ofPattern(DATE)));javaTimeModule.addDeserializer(LocalDate.class,newLocalDateDeserializer(DateTimeFormatter.ofPattern(DATE)));javaTimeModule.addSerializer(LocalTime.class,newLocalTimeSerializer(DateTimeFormatter.ofPattern(TIME)));javaTimeModule.addDeserializer(LocalTime.class,newLocalTimeDeserializer(DateTimeFormatter.ofPattern(TIME)));registerModule(javaTimeModule);}privatevoidsetSerializer(){// 1. 序列化配置 // 序列化时忽略 null 值字段不输出 null 字段setSerializationInclusion(JsonInclude.Include.NON_NULL);// 序列化空对象不抛错比如空 Bean 转 JSONconfigure(SerializationFeature.FAIL_ON_EMPTY_BEANS,false);// 日期格式统一Date 类型setDateFormat(newSimpleDateFormat(yyyy-MM-dd HH:mm:ss));setTimeZone(TimeZone.getTimeZone(ZoneId.systemDefault()));}privatevoidconfigure(){// 2. 反序列化配置 // JSON 存在 Java 对象没有的字段时不抛错最常用configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES,false);// 允许 JSON 字符串带多余的转义比如 \ 这种configure(JsonReadFeature.ALLOW_BACKSLASH_ESCAPING_ANY_CHARACTER.mappedFeature(),true);// 允许 JSON 数字用引号包裹如 age:18 → 自动转 intconfigure(JsonReadFeature.ALLOW_SINGLE_QUOTES.mappedFeature(),true);// 时间不序列化成时间戳而是字符串configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false);// 未知属性不报错configure(com.fasterxml.jackson.databind.DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES,false);}}web 注册ConfigurationpublicclassWebConfigimplementsWebMvcConfigurer{BeanpublicMappingJackson2HttpMessageConverterconfigureMessageConverters(){MappingJackson2HttpMessageConverterjackson2HttpMessageConverternewMappingJackson2HttpMessageConverter();ObjectMapperobjectMappernewCustomObjectMapper();jackson2HttpMessageConverter.setObjectMapper(objectMapper);ListMediaTypelistnewArrayList();MediaTypemediaTypenewMediaType(application,json,StandardCharsets.UTF_8);list.add(mediaType);jackson2HttpMessageConverter.setSupportedMediaTypes(list);returnjackson2HttpMessageConverter;}}