在项目中有事需要对值为NULL的对象中Field不做序列化输入配置方式如下：

[配置类型]：

源码包中的枚举类：

public static enum Include { ALWAYS, NON_NULL, NON_ABSENT, NON_EMPTY, NON_DEFAULT, USE_DEFAULTS; private Include() { }}

Include.Include.ALWAYS 默认

Include.NON_DEFAULT 属性为默认值不序列化

Include.NON_EMPTY 属性为 空（“”） 或者为 NULL 都不序列化

Include.NON_NULL 属性为NULL 不序列化

方式一：全局配置，处理所有整个应用的实体对象

#对日期类型的转换配置spring.jackson.date-format=yyyy-MM-dd HH:mm:ss # 配置 参数如下 always non_absent non_default non_empty non_null use_defaultsspring.jackson.default-property-inclusion=non_null

方式二：在需要序列的话的实体类上加注解 ->[配置类型]所列

@JsonInclude(Include.NON_NULL)

方式三：配置类型

3.1自定义序列化实现类，可以作用在类上 自定义json序列化需要实现StdSerializer<T>或者JsonSerializer<T>

@JsonSerialize(using = ClientObjectSerialize.class)public class CreditBorrowerRepaymentRequestDto{}

实现类：对字段类型转换，以及对值为null字段的过滤

public class ClientObjectSerialize extends JsonSerializer<CreditBorrowerRepaymentRequestDto>{ @Override public void serialize(CreditBorrowerRepaymentRequestDto dto, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException { jsonGenerator.writeStartObject(); try { Field[] fields = dto.getClass().getDeclaredFields(); for (Field field : fields) { field.setAccessible(true); if(null == field.get(dto)){ continue; } jsonGenerator.writeFieldName(field.getName()); jsonGenerator.writeObject(field.get(dto)); } } catch (Exception e) { e.printStackTrace(); } jsonGenerator.writeEndObject(); }}

3.2自定义序列化实现类，可以作用在实体对象字段上，对NULL值的处理，或者转换

@JsonSerialize(using = ClientStringSerialize.class)private String name; @JsonSerialize(using = ClientDtaeSerialize.class)private Date date;public class ClientStringSerialize extends JsonSerializer<String> { @Override public void serialize(String string, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException { if(string == null){ jsonGenerator.writeString(string + "[NULL]"); }else{ jsonGenerator.writeString(string); } }}public class ClientDtaeSerialize extends JsonSerializer<Date> { @Override public void serialize(Date createDate, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException { jsonGenerator.writeString(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(createDate)); }}

实践总结：

一当全局配置了NULL字段过滤的配置，但有的实体对象需要序列化出NULL的字段值，如何处理？

答：

1. 直接在对象上增加 @JsonInclude(JsonInclude.Include.ALWAYS) 类上的注解优先级比较高，会覆盖全局的配置

2.用自定义的类序列化注解（同上）

二直接在字段上加自定义序列化类会覆盖全局配置吗？

答：不会，有默认的 public class NullSerializer extends StdSerializer<Object> 来处理，当值不为Null的时候才会执行自定义字段上的序列化注解实现类

补充知识：SpringBoot中Jackson返回null处理,字符串类型转空串,数组集合转[],对象转{}

SpringBoot返回Json数据中null值处理，将字符串类型null值转换为""，将集合数组类型null值转换为[]，将原始数据类型null值转换为0，将布尔类型null值转换为false，将实体对象null值转换为{}。

1.自定义null值序列化处理器

import com.fasterxml.jackson.core.JsonGenerator;import com.fasterxml.jackson.databind.JsonSerializer;import com.fasterxml.jackson.databind.SerializerProvider;import java.io.IOException;/** * 自定义null值序列化处理器 */public class CustomizeNullJsonSerializer { /** * 处理数组集合类型的null值 */ public static class NullArrayJsonSerializer extends JsonSerializer<Object> { @Override public void serialize(Object value, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException { jsonGenerator.writeStartArray(); jsonGenerator.writeEndArray(); } } /** * 处理字符串类型的null值 */ public static class NullStringJsonSerializer extends JsonSerializer<Object> { @Override public void serialize(Object value, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException { jsonGenerator.writeString(""); } } /** * 处理数值类型的null值 */ public static class NullNumberJsonSerializer extends JsonSerializer<Object> { @Override public void serialize(Object value, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException { jsonGenerator.writeNumber(0); } } /** * 处理boolean类型的null值 */ public static class NullBooleanJsonSerializer extends JsonSerializer<Object> { @Override public void serialize(Object value, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException { jsonGenerator.writeBoolean(false); } } /** * 处理实体对象类型的null值 */ public static class NullObjectJsonSerializer extends JsonSerializer<Object> { @Override public void serialize(Object value, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException { jsonGenerator.writeStartObject(); jsonGenerator.writeEndObject(); } }}

2.序列化程序修改器

import com.fasterxml.jackson.databind.BeanDescription;import com.fasterxml.jackson.databind.SerializationConfig;import com.fasterxml.jackson.databind.ser.BeanPropertyWriter;import com.fasterxml.jackson.databind.ser.BeanSerializerModifier;import java.util.Collection;import java.util.List;/** * <pre> * 此modifier主要做的事情为： * 1.当序列化类型为数组集合时，当值为null时，序列化成[] * 2.String类型值序列化为"" * * </pre> */public class MyBeanSerializerModifier extends BeanSerializerModifier { @Override public List<BeanPropertyWriter> changeProperties(SerializationConfig config, BeanDescription beanDesc, List<BeanPropertyWriter> beanProperties) { // 循环所有的beanPropertyWriter for (int i = 0; i < beanProperties.size(); i++) { BeanPropertyWriter writer = beanProperties.get(i); // 判断字段的类型，如果是数组或集合则注册nullSerializer if (isArrayType(writer)) { // 给writer注册一个自己的nullSerializer writer.assignNullSerializer(new CustomizeNullJsonSerializer.NullArrayJsonSerializer()); } if (isStringType(writer)) { writer.assignNullSerializer(new CustomizeNullJsonSerializer.NullStringJsonSerializer()); } } return beanProperties; } /** * 是否是数组 */ private boolean isArrayType(BeanPropertyWriter writer) { Class<?> clazz = writer.getType().getRawClass(); return clazz.isArray() || Collection.class.isAssignableFrom(clazz); } /** * 是否是String */ private boolean isStringType(BeanPropertyWriter writer) { Class<?> clazz = writer.getType().getRawClass(); return CharSequence.class.isAssignableFrom(clazz) || Character.class.isAssignableFrom(clazz); } /** * 是否是数值类型 */ private boolean isNumberType(BeanPropertyWriter writer) { Class<?> clazz = writer.getType().getRawClass(); return Number.class.isAssignableFrom(clazz); } /** * 是否是boolean */ private boolean isBooleanType(BeanPropertyWriter writer) { Class<?> clazz = writer.getType().getRawClass(); return clazz.equals(Boolean.class); }}

3.配置Jackson实体

import com.fasterxml.jackson.databind.ObjectMapper;import com.fasterxml.jackson.databind.SerializerProvider;import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.Primary;import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;/** * 配置Jackson实体 */@Configurationpublic class JacksonConfig { @Bean @Primary @ConditionalOnMissingBean(ObjectMapper.class) public ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) { ObjectMapper objectMapper = builder.createXmlMapper(false).build(); /** 为objectMapper注册一个带有SerializerModifier的Factory */ objectMapper.setSerializerFactory(objectMapper.getSerializerFactory() .withSerializerModifier(new MyBeanSerializerModifier())); SerializerProvider serializerProvider = objectMapper.getSerializerProvider(); serializerProvider.setNullValueSerializer(new CustomizeNullJsonSerializer .NullObjectJsonSerializer()); return objectMapper; }}

以上这篇springboot项目中jackson-序列化-处理 NULL教程就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持。