maven工程出现这种错误，可能是tomcat里面没有dao的xml文件，这样的话要在poi里面增加代码
<build><resources><resource><directory>src/main/java</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>false</filtering></resource><resource><directory>src/main/resources</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes></resource></resources></build>灵活修改