在mysql cluster 连接的出错：
java.sql.SQLException
MESSAGE: null, message from server: “Host ‘192.168.39.147’ is blocked because of many connection errors; unblock with ‘mysqladmin flush-hosts’”
是因为mysql 最大连接数超过了其设置的值．
解决办法：
在mysql服务器上运行：mysqladmin flush-hosts,就可以解决．
Mysql 连接出错＂ unblock with ‘mysqladmin flush-hosts＇＂
原文：http://blog.csdn.net/a105421548/article/details/43705207