1. SpringBoot ResponseBody 返回值中null值處理

@PostMapping(path = '/test', produces = MediaType.APPLICATION_JSON_VALUE)public Object test() { JSONObject jsonObject = new JSONObject(); jsonObject.put('test','test'); jsonObject.put('testnull',null); ApiResponseVo apiResponseVo = new ApiResponseVo(); apiResponseVo.setData(jsonObject ); apiResponseVo.setStatus(0); return apiResponseVo;}

接口返回 (想實現將testnull也進行返回<null展示null還是0還是'' 可自定義>) :

{ 'data': { 'test': 'test' }, 'status': 0}

import java.nio.charset.Charset;import java.util.ArrayList;import java.util.List;import org.springframework.context.annotation.Configuration;import org.springframework.http.MediaType;import org.springframework.http.converter.HttpMessageConverter;import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;import com.alibaba.fastjson.serializer.SerializerFeature;import com.alibaba.fastjson.support.config.FastJsonConfig;import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;@Configurationpublic class fastJsonConfig extends WebMvcConfigurationSupport { @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, // 將 String 類型的 null 轉成''//SerializerFeature.WriteNullStringAsEmpty,// 將 Number 類型的 null 轉成 0//SerializerFeature.WriteNullNumberAsZero,// 將 List 類型的 null 轉成 []//SerializerFeature.WriteNullListAsEmpty,// 將 Boolean 類型的 null 轉成 false//SerializerFeature.WriteNullBooleanAsFalse, // 避免循環引用 SerializerFeature.DisableCircularReferenceDetect ); converter.setFastJsonConfig(config); converter.setDefaultCharset(Charset.forName('UTF-8')); List<MediaType> mediaTypeList = new ArrayList<>(); // 解決中文亂碼問題，相當于在 Controller 上的 @RequestMapping 中加了個屬性 produces = 'application/json' mediaTypeList.add(MediaType.APPLICATION_JSON); converter.setSupportedMediaTypes(mediaTypeList); converters.add(converter); }}

2. 攔截responsebody轉json,對數據進行二次處理 (字典轉換做案例)

2.1> 設置攔截器

import java.nio.charset.StandardCharsets;import java.util.List;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.http.converter.HttpMessageConverter;import org.springframework.http.converter.StringHttpMessageConverter;import org.springframework.web.servlet.config.annotation.InterceptorRegistry;import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;import com.alibaba.fastjson.serializer.SerializerFeature;import com.alibaba.fastjson.support.config.FastJsonConfig;import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;import com.fintell.dp3.manager.interceptor.LogInterceptor;@Configurationpublic class WebMvcConfiguration implements WebMvcConfigurer { @Override public void addInterceptors(InterceptorRegistry registry) { // 自定義攔截器，添加攔截路徑和排除攔截路徑 registry.addInterceptor(getLogInterceptor()).addPathPatterns('/**'); } @Bean public LogInterceptor getLogInterceptor() { return new LogInterceptor(); } /** * 修改StringHttpMessageConverter默認配置 & Json 默認序列化方式 (改這個方法) */ @Override public void configureMessageConverters(List<HttpMessageConverter<?>> converters) { //創建fastJson消息轉換器 FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter(); //創建配置類 FastJsonConfig fastJsonConfig = new FastJsonConfig(); //修改配置返回內容的過濾 fastJsonConfig.setSerializerFeatures( SerializerFeature.DisableCircularReferenceDetect, SerializerFeature.WriteMapNullValue, SerializerFeature.WriteNullStringAsEmpty ); fastConverter.setFastJsonConfig(fastJsonConfig); //將fastjson添加到視圖消息轉換器列表內 converters.add(fastConverter); }}

2.2> 字典注解類

import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target({ElementType.FIELD})@Retention(RetentionPolicy.RUNTIME)public @interface Dict { String type(); }

2.3> 序列化類

import java.io.IOException;import java.lang.reflect.Field;import org.apache.commons.lang3.StringUtils;import org.springframework.context.annotation.Configuration;import com.fasterxml.jackson.core.JsonGenerator;import com.fasterxml.jackson.databind.JsonSerializer;import com.fasterxml.jackson.databind.ObjectMapper;import com.fasterxml.jackson.databind.SerializerProvider;import lombok.extern.slf4j.Slf4j;@Slf4j@Configurationpublic class DictJsonSerializer extends JsonSerializer<Object> { @Override public void serialize(Object dictVal, JsonGenerator generator, SerializerProvider provider) throws IOException { ObjectMapper objectMapper = new ObjectMapper(); String currentName = generator.getOutputContext().getCurrentName(); try { // 1> 獲取字段 Field field = generator.getCurrentValue().getClass().getDeclaredField(currentName); // 2> 獲取字典注解 Dict dict = field.getDeclaredAnnotation(Dict.class); // 3> 判斷是否添加了字典注解 if(dict == null) { objectMapper.writeValue(generator, dictVal); return; } // 4> 獲取注解的type值 String type = dict.type(); // **************** 以下依據實際業務處理即可 ******************** // 5> 獲取到字段的值 String val = dictVal == null ? '' : dictVal.toString(); String dictValName = ''; if(!StringUtils.isEmpty(val)) {// 6> 這里可以依據type做不同的處理邏輯 dictValName = '通過自己的方法,依據val獲取到對應的字典值'; } // 7> 將字段改寫為{'code':'code','name':'name'}格式 objectMapper.writeValue(generator, BaseEnum.builder().code(dictVal).name(dictValName.toString()).build()); } catch (NoSuchFieldException e) { log.error(e); } }}

2.4> 字典注解使用

@SuppressWarnings('serial')@Builder@Getter@Setter@ToString@NoArgsConstructor@AllArgsConstructorpublic class BizRuleDto implements Serializable{ // 指定使用哪種序列化 @JsonSerialize(using = DictJsonSerializer.class) // 指定字典 (將被轉換為{'code':'content','name':'contentname'}格式) @Dict(type = 'content') private String content;}

3. 其它補充 (從容器中獲取某個實例) : 如 DictJsonSerializer 需要通過service查詢數據庫獲取字典

@Slf4jpublic class DictJsonSerializer extends JsonSerializer<Object> { // service private static ProductProxy productProxy; static { productProxy = SpringUtils.getBean(ProductProxy.class); } @Override public void serialize(Object dictVal, JsonGenerator generator, SerializerProvider provider) throws IOException { }}

SpringUtils

import org.springframework.beans.BeansException;import org.springframework.context.ApplicationContext;import org.springframework.context.ApplicationContextAware;import org.springframework.stereotype.Component;@Componentpublic class SpringUtils implements ApplicationContextAware { private static ApplicationContext ctx; /** * 獲取bean */ @SuppressWarnings('unchecked') public static <T> T getBean(String id) { return (T) ctx.getBean(id); } /** * 按類型獲取bean */ public static <T> T getBean(Class<T> clazz) { return ctx.getBean(clazz); } @Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { ctx = applicationContext; }}

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