原文鏈接:http://www.cnblogs.com/dingchenghong/archive/2012/07/04/2576504.html
項目中用mybatis3.x,用sql查詢某個表類型爲int的字段,那個表是空表,沒有數據,結果拋異常了,原因是在對象中的屬性爲int,空表時,sql查詢出來的是NULL,結果賦值時拋異常了。
org.apache.ibatis.binding.BindingException: Mapper method 'getSort' (xx.yy.cc.DxxDAO) attempted to return null from a method with a primitive return type (int).
拋這樣的異常。
解決這個問題,是當查出來爲NULL時,結一個默認值,如:0。
SELECT IFNULL(MAX(SORT),0)AS sort FROM web_d_info
SELECT nvl(MAX(SORT),0) as sort FROM web_d_info
如果上述方法無效,請使用以下解決方案:
轉:http://blog.csdn.NET/just_lion/article/details/9700793
當配置mybatis返回int類型時
- select id="getUserIdByName" parameterType="string" resultType="int">
- SELECT
- id
- FROM user
- WHERE userName = #{userName}
- </select>
會報錯如下:
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.apache.ibatis.binding.BindingException: Mapper method 'com.bill.springMybatis.dao.UserDao.getUserIdByName attempted to return null from a method with a primitive
return type (int).
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.Java:894)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
解決方案,返回類型設置爲封裝類型Integer而不是基本類型int
- <?xml version="1.0" encoding="UTF-8"?>
- <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
- "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
- <mapper namespace="com.bill.springMybatis.dao.UserDao">
- <cache />
- <select id="getUserIdByName" parameterType="string" resultType="Integer">
- SELECT
- id
- FROM user
- WHERE userName = #{userName}
- </select>
- </mapper>
service層如果需要int數據類型,可以自動從Integer進行轉換, 當然有可能加入一些判斷,比如Integer爲Null,賦給int可以先轉成0