Mybatis懶載入時,springMVC返回JSON異常 Could not write JSON: No serializer found for class org.apache.ibatis.executor.loader.javassist.JavassistProxyFactory$En
阿新 • • 發佈:2018-12-31
在mybatis整合springmvc時,假如mybatis採用了懶載入,而springmvc中利用@ResponseBody註解返回實體類的JSON時會拋異常:
Could not write JSON: No serializer found for class org.apache.ibatis.executor.loader.javassist.JavassistProxyFactory$EnhancedResultObjectProxyImpl and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS);
先看出現問題的程式碼:
首先是controller中返回的是responsebody:
/** * 根據訂單ID查詢訂單 * @param orderId * @return */ @ResponseBody @RequestMapping(value = "/query/{orderId}" ,method = RequestMethod.GET) public Order queryOrderById(@PathVariable("orderId") String orderId) { return orderService.queryOrderById(orderId); }
service中的程式碼:
public Order queryOrderById(String orderId) { Order order = orderDao.queryOrderById(orderId); return order; }
public Order queryOrderById(String orderId) { return this.orderMapper.queryByID(orderId); }
呼叫的mapper.xml中使用了懶載入:
<resultMap type="Order" id="pojoResultMap" autoMapping="true"> <id column="order_id" property="orderId"/> <association property="orderShipping" javaType="OrderShipping" column="order_id" select="queryOrderShippingByOrderId" autoMapping="true" fetchType="lazy"></association> <collection property="orderItems" javaType="Arraylist" ofType="OrderItem" autoMapping="true" select="queryOrderItemByOrderId" column="order_id" fetchType="lazy"> </collection> </resultMap>
這個時候測試就會上面的異常.
經過除錯後發現,原來service中執行過queryByID的方法後,返回的實體類Order被做了代理,如下:
可以看到,被代理後的Order類多了一個handler的屬性,之後Jackson在對該代理類做序列化時,由於找不到對應的getter,異常就丟擲來辣!
解決方法:
在被代理的Order類上加上 @JsonIgnoreProperties(value = "handler") 註解,讓Jackson序列化時忽略handler屬性:
問題解決!