content: package com.java2nb.novel.core.advice;
  
  import com.fasterxml.jackson.databind.ObjectMapper;
  import com.fasterxml.jackson.databind.module.SimpleModule;
  import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;
  import org.springframework.core.MethodParameter;
  import org.springframework.http.MediaType;
  import org.springframework.http.converter.HttpMessageConverter;
  import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
  import org.springframework.http.server.ServerHttpRequest;
  import org.springframework.http.server.ServerHttpResponse;
  import org.springframework.web.bind.annotation.RestControllerAdvice;
  import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;
  
  import java.util.Objects;
  
  /**
   * 在对 RestController 返回对象 json 序列化时，将所有 Long 类型转为 String 类型返回，避免前端数据精度丢失的问题
   * 取代 spring.jackson.generator.write-numbers-as-strings=true 配置，避免影响全局的 ObjectMapper
   *
   * @author xiongxiaoyang
   * */
  @RestControllerAdvice
  public class CustomResponseBodyAdvice implements ResponseBodyAdvice<Object> {
  
      private final ObjectMapper customObjectMapper;
  
      public CustomResponseBodyAdvice(Jackson2ObjectMapperBuilder builder) {
          customObjectMapper = builder.createXmlMapper(false).build();
          SimpleModule simpleModule = new SimpleModule();
          simpleModule.addSerializer(Long.class, ToStringSerializer.instance);
          simpleModule.addSerializer(Long.TYPE, ToStringSerializer.instance);
          customObjectMapper.registerModule(simpleModule);
      }
  
      @Override
      public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {
          // 返回 true 表示对所有 Controller 的响应都生效
          return true;
      }
  
      @Override
      public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class<? extends HttpMessageConverter<?>> selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) {
          // 使用自定义的 ObjectMapper 序列化响应体
          if(Objects.nonNull(body)) {
              return customObjectMapper.valueToTree(body);
          }else{
              return null;
          }
      }
  
  }
  
  