使用JSON.toJSONString格式化成json字串時保留null屬性

com.alibaba.fastjson.JSON

public static String parseScriptJsonStringWithNullValue(Object obj) { 
   if (obj == null || (obj instanceof Undefined)) { 
      return null; 
   } 
   return JSON.toJSONString(obj, new SerializeFilter[]{scriptArrayFilter}, SerializerFeature.WriteMapNullValue); 
}

SerializerFeature.WriteMapNullValue

String ret = JSON.toJSONStringWithDateFormat(returnValue, "yyyy-MM-dd HH:mm:ss",
                SerializerFeature.PrettyFormat,
                    // 保留map空的欄位
                    SerializerFeature.WriteMapNullValue,
                    // 將String型別的null轉成""
                    SerializerFeature.WriteNullStringAsEmpty,
                    // 將Number型別的null轉成0
                    SerializerFeature.WriteNullNumberAsZero,
                    // 將List型別的null轉成[]
                    SerializerFeature.WriteNullListAsEmpty,
                    // 將Boolean型別的null轉成false
                    SerializerFeature.WriteNullBooleanAsFalse,
                    // 避免迴圈參照
                    SerializerFeature.DisableCircularReferenceDetect
                );

package com.aiqin.mgs.market.api.config; 
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
 
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
 
/**
 * description: fastjson處理返回的引數為null、或者不返回
 * date: 2019/11/22 15:03
 * author: hantao
 * version: 1.0
 * springboot 處理返回結果中欄位為空或為null，不展示欄位的問題（欄位展示不全）
 */
@Configuration
public class FastJsonConfiguration extends WebMvcConfigurationSupport {
 
    /**
     * 使用阿里 fastjson 作為JSON MessageConverter
     * @param converters
     */
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        FastJsonHttpMessageConverter converter = new FastJsonHttpMessageConverter();
        FastJsonConfig config = new FastJsonConfig();
        config.setSerializerFeatures(
                // 保留map空的欄位
                SerializerFeature.WriteMapNullValue,
                // 將String型別的null轉成""
                SerializerFeature.WriteNullStringAsEmpty,
                // 將Number型別的null轉成0
                SerializerFeature.WriteNullNumberAsZero,
                // 將List型別的null轉成[]
                SerializerFeature.WriteNullListAsEmpty,
                // 將Boolean型別的null轉成false
                SerializerFeature.WriteNullBooleanAsFalse,
                // 避免迴圈參照
                SerializerFeature.DisableCircularReferenceDetect);
 
        converter.setFastJsonConfig(config);
        converter.setDefaultCharset(Charset.forName("UTF-8"));
        List<MediaType> mediaTypeList = new ArrayList<>();
        // 解決中文亂碼問題，相當於在Controller上的@RequestMapping中加了個屬性produces = "application/json"
        mediaTypeList.add(MediaType.APPLICATION_JSON);
        converter.setSupportedMediaTypes(mediaTypeList);
        converters.add(converter);
    }
 
    /**
     * 整合了swagger需要設定swagger攔截
     * @param registry
     */
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("swagger-ui.html","index.html").addResourceLocations("classpath:/META-INF/resources/");
        registry.addResourceHandler("doc.html").addResourceLocations("classpath:/META-INF/resources/");
        registry.addResourceHandler("/webjars/**").addResourceLocations("classpath:/META-INF/resources/webjars/");
        registry.addResourceHandler("/static/**").addResourceLocations("classpath:/META-INF/resources/static/");
    } 
}