使用JSON.toJSONString格式化成json字符串时保留null属性
目录
JSON.toJSONString格式化成json字符串时保留null属性
使用阿里的
com.alibaba.fastjson.JSON
格式化时，默认null属性会被过滤掉，可以设置不过滤null
public static String parseScriptJsonStringWithNullValue(Object obj) {
if (obj == null || (obj instanceof Undefined)) {
return null;
}
return JSON.toJSONString(obj, new SerializeFilter[]{scriptArrayFilter}, SerializerFeature.WriteMapNullValue);
}
指定这个参数即可
SerializerFeature.WriteMapNullValue
属性说明
QuoteFieldNames———输出key时是否使用双引号,默认为true
WriteMapNullValue———是否输出值为null的字段,默认为false
WriteNullNumberAsZero———数值字段如果为null,输出为0,而非null
WriteNullListAsEmpty———List字段如果为null,输出为[],而非null
WriteNullStringAsEmpty———字符类型字段如果为null,输出为”“,而非null
WriteNullBooleanAsFalse———Boolean字段如果为null,输出为false,而非null
例子
String ret = JSON.toJSONStringWithDateFormat(returnValue, "yyyy-MM-dd HH:mm:ss", SerializerFeature.PrettyFormat, // 保留map空的字段 SerializerFeature.WriteMapNullValue, // 将String类型的null转成"" SerializerFeature.WriteNullStringAsEmpty, // 将Number类型的null转成0 SerializerFeature.WriteNullNumberAsZero, // 将List类型的null转成[] SerializerFeature.WriteNullListAsEmpty, // 将Boolean类型的null转成false SerializerFeature.WriteNullBooleanAsFalse, // 避免循环引用 SerializerFeature.DisableCircularReferenceDetect );
处理返回结果中字段为空或为null,不展示字段的问题(字段展示不全)
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处理返回的参数为null、或者不返回
* date: 2019/11/22 15:03
* author: hantao
* version: 1.0
* springboot 处理返回结果中字段为空或为null，不展示字段的问题（字段展示不全）
*/
@Configuration
public class FastJsonConfiguration extends WebMvcConfigurationSupport {
/**
* 使用阿里 fastjson 作为JSON MessageConverter
* @param converters
*/
@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
FastJsonHttpMessageConverter converter = new FastJsonHttpMessageConverter();
FastJsonConfig config = new FastJsonConfig();
config.setSerializerFeatures(
// 保留map空的字段
SerializerFeature.WriteMapNullValue,
// 将String类型的null转成""
SerializerFeature.WriteNullStringAsEmpty,
// 将Number类型的null转成0
SerializerFeature.WriteNullNumberAsZero,
// 将List类型的null转成[]
SerializerFeature.WriteNullListAsEmpty,
// 将Boolean类型的null转成false
SerializerFeature.WriteNullBooleanAsFalse,
// 避免循环引用
SerializerFeature.DisableCircularReferenceDetect);
converter.setFastJsonConfig(config);
converter.setDefaultCharset(Charset.forName("UTF-8"));
List<MediaType> mediaTypeList = new ArrayList<>();
// 解决中文乱码问题，相当于在Controller上的@RequestMapping中加了个属性produces = "application/json"
mediaTypeList.add(MediaType.APPLICATION_JSON);
converter.setSupportedMediaTypes(mediaTypeList);
converters.add(converter);
}
/**
* 整合了swagger需要配置swagger拦截
* @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/");
}
}
/**
37 * 过滤器,发现传入的是null时,转化为""
38 */
39 ValueFilter filter = new ValueFilter() {
40 @Override
41 public Object process(Object obj, String s, Object v) {
42 if (v == null)
43 return "";
44 return v;
45 }
46 };
47
48 // 添加过滤器
49 System.out.println(JSONObject.toJSONString(jsonMap, filter));