InvalidDefinitionException：找不到内部类的序列化程序

Posted 2023-02-26

【中文标题】InvalidDefinitionException：找不到内部类的序列化程序

【英文标题】：InvalidDefinitionException: No serializer found for inner class

【发布时间】：2019-08-04 13:24:18

【问题描述】：

我有这门课，我想以JSON 格式返回RestAPI 调用

return ResponseEntity.ok().cacheControl(CacheControl.maxAge(5, TimeUnit.MINUTES))
                    .body(hotelChart2);

类：

public class HotelChart2 



    public HotelChart2() 
        super();
    

    public class Statistics 

         double min;
         double max;
         double average;

         public Statistics() 
            super();
         

        public Statistics(double min, double max, double average) 
            super();
            this.min = min;
            this.max = max;
            this.average = average;
        

    

    Map<LocalDateTime, DoubleSummaryStatistics> las24HPerHour;

    Map<LocalDate, Statistics> last30DPerDay;

    Map<LocalDate, Statistics> last3MPerDay;

    Map<LocalDate, Statistics> last6MPerDay;

    Map<LocalDate, Statistics> last1YPerDay;



    public Map<LocalDateTime, DoubleSummaryStatistics> getLas24HPerHour() 
        return las24HPerHour;
    

    public void setLas24HPerHour(Map<LocalDateTime, DoubleSummaryStatistics> las24hPerHour) 
        las24HPerHour = las24hPerHour;
    

    public Map<LocalDate, Statistics> getLast30DPerDay() 
        return last30DPerDay;
    

    public void setLast30DPerDay(Map<LocalDate, Statistics> last30dPerDay) 
        last30DPerDay = last30dPerDay;
    

    public Map<LocalDate, Statistics> getLast3MPerDay() 
        return last3MPerDay;
    

    public void setLast3MPerDay(Map<LocalDate, Statistics> last3mPerDay) 
        last3MPerDay = last3mPerDay;
    

    public Map<LocalDate, Statistics> getLast6MPerDay() 
        return last6MPerDay;
    

    public void setLast6MPerDay(Map<LocalDate, Statistics> last6mPerDay) 
        last6MPerDay = last6mPerDay;
    




    public Map<LocalDate, Statistics> getLast1YPerDay() 
        return last1YPerDay;
    

    public void setLast1YPerDay(Map<LocalDate, Statistics> last1yPerDay) 
        last1YPerDay = last1yPerDay;
    

但我收到了这个错误：

Type definition error: [simple type, class com.tdk.api.json.HotelChart2$Statistics]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class com.tdk.api.json.HotelChart2$Statistics and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: com.tdk.api.json.HotelChart2["last3MPerDay"]->java.util.HashMap["2019-01-27"])
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:293)
    at org.springframework.http.converter.AbstractGenericHttpMessageConverter.write(AbstractGenericHttpMessageConverter.java:103)
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:290)

【参考方案1】：

这两种解决方案中的任何一种都有效！

公开所有成员（默认情况下，Jackson 在公共成员字段上工作）

 public double min; //note: members are made public
 public double max;
 public double average;
 public Map<LocalDateTime, DoubleSummaryStatistics> las24HPerHour;
 // ..... modify all map as public

如果要修改 Jackson 默认属性，请修改 ObjectMapper

ObjectMapper objectMapper = new ObjectMapper();
objectMapper.setVisibility(mapper.getVisibilityChecker()
             .withFieldVisibility(JsonAutoDetect.Visibility.ANY));

【参考方案2】：

您需要将getters 添加到您的内部Statistics 类（首选）或在ObjectMapper 级别启用fields 可见性：

ObjectMapper mapper = new ObjectMapper();
mapper.setVisibility(mapper.getVisibilityChecker()
     .withFieldVisibility(JsonAutoDetect.Visibility.ANY));