这是mybatis-config.xml：

<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"         "http://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration>     <environments default="development">         <environment id="development">             <transactionManager type="JDBC"/>             <dataSource type="POOLED">                 <property name="driver" value="com.mysql.jdbc.Driver"/>                 <property name="url"                           value="jdbc:mysql://localhost:3306/jupan_mail?useUnicode=true&amp;characterEncoding=UTF-8&amp;"/>                 <property name="username" value="root"/>                 <property name="password" value="password"/>             </dataSource>         </environment>     </environments>     <mappers>         <mapper resource="com/salamander/backcal/mapping/MailChangeMapper.xml"/>     </mappers> </configuration>

这是项目结构：

单元测试报错：
Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: java.io.IOException: Could not find resource com/salamander/backcal/dao/MailChangeMapper.xml