可能的原因:

1、将mapper.xml的文件头的部分UTF-8修改为UTF8

<?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">
<!--namespace=绑定一个对应的dao、Mapper接口-->
<mapper namespace="com.pcz.dao.UserMapper">