1. SpringBoot ResponseBody 返回值中null值处理
@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 (想实现将testnull也进行返回<null展示null还是0还是"" 可自定义>) :
{ "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; @Configuration public 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, // 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); } }
2. 拦截responsebody转json,对数据进行二次处理 (字典转换做案例)
2.1> 设置拦截器
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; @Configuration public class WebMvcConfiguration implements WebMvcConfigurer { @Override public void addInterceptors(InterceptorRegistry registry) { // 自定义拦截器,添加拦截路径和排除拦截路径 registry.addInterceptor(getLogInterceptor()).addPathPatterns("/**"); } @Bean public LogInterceptor getLogInterceptor() { return new LogInterceptor(); } /** * 修改StringHttpMessageConverter默认配置 & Json 默认序列化方式 (改这个方法) */ @Override public void configureMessageConverters(List<HttpMessageConverter<?>> converters) { //创建fastJson消息转换器 FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter(); //创建配置类 FastJsonConfig fastJsonConfig = new FastJsonConfig(); //修改配置返回内容的过滤 fastJsonConfig.setSerializerFeatures( SerializerFeature.DisableCircularReferenceDetect, SerializerFeature.WriteMapNullValue, SerializerFeature.WriteNullStringAsEmpty ); fastConverter.setFastJsonConfig(fastJsonConfig); //将fastjson添加到视图消息转换器列表内 converters.add(fastConverter); } }
2.2> 字典注解类
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> 序列化类
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 @Configuration public 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> 获取字段 Field field = generator.getCurrentValue().getClass().getDeclaredField(currentName); // 2> 获取字典注解 Dict dict = field.getDeclaredAnnotation(Dict.class); // 3> 判断是否添加了字典注解 if(dict == null) { objectMapper.writeValue(generator, dictVal); return; } // 4> 获取注解的type值 String type = dict.type(); // **************** 以下依据实际业务处理即可 ******************** // 5> 获取到字段的值 String val = dictVal == null ? "" : dictVal.toString(); String dictValName = ""; if(!StringUtils.isEmpty(val)) { // 6> 这里可以依据type做不同的处理逻辑 dictValName = "通过自己的方法,依据val获取到对应的字典值"; } // 7> 将字段改写为{"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 @AllArgsConstructor public class BizRuleDto implements Serializable{ // 指定使用哪种序列化 @JsonSerialize(using = DictJsonSerializer.class) // 指定字典 (将被转换为{"code":"content","name":"contentname"}格式) @Dict(type = "content") private String content; }
3. 其它补充 (从容器中获取某个实例) : 如 DictJsonSerializer 需要通过service查询数据库获取字典
@Slf4j public 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; @Component public class SpringUtils implements ApplicationContextAware { private static ApplicationContext ctx; /** * 获取bean */ @SuppressWarnings("unchecked") public static <T> T getBean(String id) { return (T) ctx.getBean(id); } /** * 按类型获取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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