Error parsing Mapper XML. Cause: java.lang.NullPointerException

springmvc与mybatis整合出现的异常：
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userHandler': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userServiceImp': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userMapper' defined in file [G:\tomcat\apache-tomcat-7.0.57\webapps\springmvc_mybatis\WEB-INF\classes\com\tanghaibin\mapper\UserMapper.class]: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. Cause: java.lang.NullPointerException
Related cause: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userMapper' defined in file [G:\tomcat\apache-tomcat-7.0.57\webapps\springmvc_mybatis\WEB-INF\classes\com\tanghaibin\mapper\UserMapper.class]: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. Cause: java.lang.NullPointerException

解决：
mapper配置文件中的namespace没有填；而且namespase的值应该填为：mapper的权限定名；否则还是会抛出异常