java.sql.SQLException: null, message from server: “Host ‘xx‘ is blocked because of many co

java.sql.SQLException: null, message from server: "Host 'xx' is blocked because of many  connection errors; unblock with 'mysqladmin flush-hosts'

出现这个的原因是错误连接达到数据库设置的最大值。

此时需要释放重置连接最大值。

进入mysql使用命令

flush-hosts;