MyBatis DTD [Element type “if“ must be declared]
MyBatis DTD [Element type "if" must be declared]

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

Downloading external resources is disabled.
http://mybatis.org/dtd/mybatis-3-mapper.dtd


下载到本地放到项目的src/main/resources里面也可以,

修改XML头部定义
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "classpath:mybatis-3-mapper.dtd">

Cannot find DTD 'classpath:mybatis-3-mapper.dtd'.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "file:C:\Users\Administrator\Desktop\mybatis-3-mapper.dtd">
======
把XML校验全部关闭

