java.sql.SQLException: null, message from server: “Host ‘xxx’ is not allowed to connect
java.sql.SQLException: null, message from server: "Host 'xxx' is not allowed to connect to this MySQL server"：
java.sql.SQLException: Access denied for user 'root'@'xxx.xxx.xxx.xxx' at (数据库名)
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;
无论使用哪种方案，请重启Mysql服务。