问题描述：

java.sql.SQLException: Unknown initial character set index ‘255‘ received from server. 
Initial client character set can be forced via the ‘characterEncoding‘ property.

原因分析：

MySQL驱动和数据库字符集设置不搭配

解决方案：

添加 ?useUnicode=true&characterEncoding=utf8

"jdbc:mysql:///maven02?useUnicode=true&characterEncoding=utf8","用户名","密码")          

成功解决

Unknown initial character set index ‘255‘ received from server. Initial client character 解决方法

原文：https://www.cnblogs.com/Slience-me/p/14674460.html