mybatis配置文件 org.xml.sax.SAXParseException; lineNumber: 3; columnNumber: 16; 文档根元素 "configuration" 必须

将配置文件中 

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

修改为：

<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">