登录数据库查看用户权限，如果如下，没有开放对外权限，连接不上，需要配置权限
mysql> select user,host from mysql.user;
+---------------+-----------+
| user | host |
+---------------+-----------+
| mysql.session | localhost |
| mysql.sys | localhost |
| root | localhost |
+---------------+-----------+
3 rows in set (0.00 sec)
#GRANT ALL PRIVILEGES ON *.* TO 'root'@'主机' IDENTIFIED BY '密码' WITH GRANT OPTION;
# %：代表所有主机
grant all privileges on *.* to 'root'@'%' identified by '123456' with grant option;
flush privileges; #刷新权限