控制台的error日志：

org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class com...entity..[某一具体实体类]]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class com...entity..[某一具体实体类] and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS)

划重点：

• org.springframework.http.converter.HttpMessageConversionException
• Type definition error 定义错误
• No serializer found 序列化器无法找到
• no properties discovered 属性没法找到（没有getter、setter）

原因

忘记在实体类上加 @Data 注解

解决

对应的实体类上加上 @Data 注解