java.sql.SQLException: null, message from server: "Host 'xxx' is not allowed to connect to this MySQ

表示该对象不是远程对象，不能通过该对象远程访问数据

解决：

方案一：改表：

use mysql ;select user,host,password from user;

update user set host = '%' where user='root';

方案二：授权法：

例如，你想myuser使用mypassword从任何主机连接到mysql服务器的话。 
GRANT ALL PRIVILEGES ON *.* TO 'myuser'@'%' IDENTIFIED BY 'mypassword' WITH GRANT OPTION; 
如果你想允许用户myuser从ip为192.168.1.3的主机连接到mysql服务器，并使用mypassword作为密码 

GRANT ALL PRIVILEGES ON *.* TO 'myuser'@'192.168.1.3' IDENTIFIED BY 'mypassword' WITH GRANT OPTION;