SpringBoot Jackson 将null转字符串"" ，List、Array转[]，Int转0_星光的博客-CSDN博客
import com.fasterxml.jackson.core.JsonGenerator;import com.fasterxml.jackson.core.JsonProcessingException;import com.fasterxml.jackson.databind.BeanDescription;import com.fasterxml.jackson.databind.JsonSerializer;import com.fasterxml.jackson.databind.SerializationConfig;import com.fasterxml.jackson.databind.SerializerProvider;import com.fasterxml.jackson.databind.ser.BeanPropertyWriter;import com.fasterxml.jackson.databind.ser.BeanSerializerModifier;import org.apache.commons.lang3.StringUtils;import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter; import java.io.IOException;import java.util.Collection;import java.util.List; /** * 使用官方自带的json格式类库，fastjson因为content type问题时不时控制台报错、无法直接返回二进制等问题 */class JacksonHttpMessageConverter extends MappingJackson2HttpMessageConverter { /** * 处理数组类型的null值 */ public class NullArrayJsonSerializer extends JsonSerializer<Object> { @Override public void serialize(Object value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException { if (value == null) { jgen.writeStartArray(); jgen.writeEndArray(); } } } /** * 处理字符串类型的null值 */ public class NullStringJsonSerializer extends JsonSerializer<Object> { @Override public void serialize(Object o, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException { jsonGenerator.writeString(StringUtils.EMPTY); } } /** * 处理数字类型的null值 */ public class NullNumberJsonSerializer extends JsonSerializer<Object> { @Override public void serialize(Object o, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException { jsonGenerator.writeNumber(0); } } /** * 处理布尔类型的null值 */ public class NullBooleanJsonSerializer extends JsonSerializer<Object> { @Override public void serialize(Object o, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException { jsonGenerator.writeBoolean(false); } } public class MyBeanSerializerModifier extends BeanSerializerModifier { @Override public List<BeanPropertyWriter> changeProperties(SerializationConfig config, BeanDescription beanDesc, List<BeanPropertyWriter> beanProperties) { //循环所有的beanPropertyWriter for (Object beanProperty : beanProperties) { BeanPropertyWriter writer = (BeanPropertyWriter) beanProperty; //判断字段的类型，如果是array，list，set则注册nullSerializer if (isArrayType(writer)) { //给writer注册一个自己的nullSerializer writer.assignNullSerializer(new NullArrayJsonSerializer()); } else if (isNumberType(writer)) { writer.assignNullSerializer(new NullNumberJsonSerializer()); } else if (isBooleanType(writer)) { writer.assignNullSerializer(new NullBooleanJsonSerializer()); } else if (isStringType(writer)) { writer.assignNullSerializer(new 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int */ 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); } } JacksonHttpMessageConverter() { getObjectMapper().setSerializerFactory(getObjectMapper().getSerializerFactory().withSerializerModifier(new MyBeanSerializerModifier())); } }一定要在下面配置消息转换器，不然没效果
@Configurationpublic class WebMvcConfig extends WebMvcConfigurationSupport { @Override protected void configureMessageConverters(List<HttpMessageConverter<?>> converters) { super.configureMessageConverters(converters); converters.add(new JacksonHttpMessageConverter()); } }如果想要更丰富的可以在：MyBeanSerializerModifier中自定义。
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创建于: 2021-11-02 11:17:19
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