org.apache.ibatis.exceptions.PersistenceException: ### Error building SqlSession. ### The error may

跟着mybatis官方文档再次学习mybatis，果然，还是不记得一些配置了…

同时，官方文档也是坑小白哦

官方文档中文 http://www.mybatis.org/mybatis-3/zh/getting-started.html

在使用xml配置文件进行sqlsession获取的时候出现以下报错

org.apache.ibatis.exceptions.PersistenceException: ### Error building SqlSession.### The error may exist in com/wy/bean/StudentMapper.xml### Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration.     Cause: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML.     Cause: org.apache.ibatis.builder.BuilderException: Error resolving class.     Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'Student'.     Cause: java.lang.ClassNotFoundException: Cannot find class: Student

看报错提示很明显知道是Student这个类找不到，同时提示了可能发生错误的地方是

The error may exist in com/wy/bean/StudentMapper.xml

以下是我的mapper文件

<?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.wy.bean.StudentMapper">  <!-- 查找所有学生 -->  <select id="selectAllStudent" resultType="Student" >    select * from student  </select></mapper>

官方的mapper配置文件

<?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="org.mybatis.example.BlogMapper">  <select id="selectBlog" resultType="Blog">    select * from Blog where id = #{id}  </select></mapper>

仔细看resultType那块！直接是一个类名，然而在mybatis-config.xml中也没有配置类别名的相关配置，SO，被文档坑了…

解决方案

在mybatis-config.xml没有配置类别名的时候需要写上类的全路径

<?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.wy.bean.StudentMapper">  <!-- 查找所有学生 -->  <!-- 注意:在mybatis-config.xml没有配置类别名的时候需要写上类的全路径 -->  <select id="selectAllStudent" resultType="com.wy.bean.Student" >    select * from student  </select></mapper>