错误：
Caused by: java.sql.SQLException: Unknown initial character set index '255' received from server. Initial client character set can be forced via the 'characterEncoding' property.
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1055)
原因：
这是编码不匹配的原因，MySQL驱动和数据库字符集设置不搭配，默认字符集已从latin1变成utf8mb4，因而系统变量受到影响
解决办法：
在后面加上这样一段代码：
<property name="url" value="jdbc:mysql://localhost:3306/eesy_mybatis?characterEncoding=utf8"/>
解决了
标签：index,set,Unknown,Initial,character,via,255 From： https://www.cnblogs.com/dbconfig1/p/16922137.html