1.场景

启动整合mybatis的springboot项目，报异常如下：

 Factory method 'sqlSessionFactory' threw exception; nested exception is org.springframework.core.NestedIOException: Failed to parse mapping resource: 'file [D:\Git\target\classes\mappers\system\SysMenuMapper.xml]'; nested exception is org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'file [D:\Git\target\classes\mappers\system\SysMenuMapper.xml]'. Cause: java.lang.IllegalArgumentException: Result Maps collection already contains value for com.system.mapper.SysMenuMapper.BaseResultMap

2.分析

java.lang.IllegalArgumentException: Result Maps collection already contains value for com.system.mapper.SysMenuMapper.BaseResultMap

在mybatis的xml文件的com.system.mapper.SysMenuMapper.BaseResultMap早已经存在，检查SysMenuMapper.xml
该文件发现BaseResultMap的id命名重复了

3.解决

找到SysMenuMapper.xml的id重复命名去掉重新启动，解决了