后台controller返回前台json HttpMessageNotWritableException报错的解决办法

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/wuxiao_wei/article/details/83986783

报错信息如下：

2018-11-12 09:25:14.644  WARN 9416 --- [nio-8080-exec-2] .w.s.m.s.DefaultHandlerExceptionResolver : Failed to write HTTP message: org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS)
 

分析：报错的类==>org.springframework.http.converter.HttpMessageNotWritableException

原因：Could not write JSON: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS);

重点：FAIL_ON_EMPTY_BEANS

那么，显然，json 序列化失败，失败的原因是 返回的类属性里有空值，在数据里查数据发现

确实有空值 则 ，在实体类中加入注解

@JsonSerialize(include=Inclusion.NON_EMPTY) 

当然这个注解可以作为全局注解 放在类上，也可以作为局部注解，放在某个具体字段上 

这个注解似乎失效了，但还能用。到此结束。