mybatis3的mapper文件报Referenced file contains errors

最近使用mybatis.3.1.0时无意中碰到一个问题：

The errors below were detected when validating the file "mybatis-3-mapper.dtd" via the file "account-mapper.xml".  In most cases these errors can be detected by validating "mybatis-3-mapper.dtd" directly.  However it is possible that errors will only occur when mybatis-3-mapper.dtd is validated in the context of account-mapper.xml.

 解决方案：

将
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
改为
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://www.mybatis.org/dtd/mybatis-3-mapper.dtd">