IDEA启动项目报错Communications link failure的解决方案

问题描述

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

解决方案

方案1.  Tomcat配置VM参数：-Djava.net.preferIPv4Stack=true

方案2.  ①Nginx配置代理MySQL：

    ②修改数据库连接：spring.datasource.url=jdbc:mysql://localhost:9999/demo?characterEncoding=utf8

参考来自：

https://blog.youkuaiyun.com/baidu_21349635/article/details/121032229
https://adong.blog.youkuaiyun.com/article/details/111501253