查看编译后的classes文件后，没有mapper.xml文件，所以SQLsessionfactory不能读取成功。
在Maven中加入如下的resources配置：
<dependencies>
//相关的依赖包
</dependencies>
.....
<resources>
<resource>
<directory>src/main/resources</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
<include>**/*.tld</include>
</includes>
<filtering>false</filtering>
</resource>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
<include>**/*.tld</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>
原文：http://www.cnblogs.com/expiator/p/7494965.html