必须为元素类型mapper声明属性namespace解决

项目目录结构

UserMapper和UserMapper.xml统一放到mapper下了,SqlMapConfig.xml为mybatis的系统配置文件



<configuration><environments default&＃61;"development"><environment id&＃61;"development"><transactionManager type&＃61;"JDBC"/><dataSource type&＃61;"POOLED"><property name&＃61;"driver" value&＃61;"com.mysql.jdbc.Driver"/><property name&＃61;"url" value&＃61;"jdbc:mysql://localhost:3306/mybatis?characterEncoding&＃61;utf-8"/><property name&＃61;"username" value&＃61;"root"/><property name&＃61;"password" value&＃61;"123456"/>dataSource>environment>environments><mappers><mapper resource&＃61;"cn/itheima/pojo/User.xml"/><mapper class&＃61;"cn.itheima.mapper.UserMapper"/>mappers>
configuration>

UserMapper.xml



<mapper namespace&＃61;"cn.itheima.mapper.UserMapper"><select id&＃61;"findUserById" parameterType&＃61;"int" resultType&＃61;"cn.itheima.pojo.User">select * from user where id &＃61; #{id}select><select id&＃61;"findUserByUserName" parameterType&＃61;"String" resultType&＃61;"cn.itheima.pojo.User">select * from user where username like &＃39;%${value}%&＃39;select><insert id&＃61;"insertUser" parameterType&＃61;"cn.itheima.pojo.User">/*执行select LAST_INSERT_ID()数据函数,返回自增的主键keyProperty:将返回的主键放入传入参数的id中保存order:当前函数相对于insert语句的执行顺序,在insert之前执行是before,在insert后执行是afterresultType:id的类型,也是keyProperty中属性的类型*/<selectKey keyProperty&＃61;"id" order&＃61;"AFTER" resultType&＃61;"int">select LAST_INSERT_ID()selectKey>insert into user (username,birthday,sex,address) values (#{username},#{birthday},#{sex},#{address})insert>
mapper>


网上找了一下发现我的UserMapper.xml下应该引错了

应该将Config改成mapper,改好从新测试,问题解决