【已解决】数据库连接报错：com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

最新推荐文章于 2025-04-23 17:24:44 发布

旅人杰

最新推荐文章于 2025-04-23 17:24:44 发布

阅读量6.8w

点赞数 18

分类专栏： Exception 文章标签： mysql 数据库 java

本文链接：https://blog.youkuaiyun.com/qq_42554719/article/details/114626130

版权

Exception 专栏收录该内容

2 篇文章

订阅专栏

本文针对Java应用程序中出现的MySQL连接失败问题，提供了详细的排查及解决方案，包括检查URL、用户名、密码，验证用户权限，配置防火墙及开放端口，确保驱动版本匹配等。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

报错信息：

java.sql.SQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

java.sql.SQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:110) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:73) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.mysql.cj.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:903) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:828) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:453) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198) ~[mysql-connector-java-8.0.23.jar:8.0.23]
	at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:156) ~[druid-1.1.16.jar:1.1.16]
	at com.alibaba.druid.filter.stat.StatFilter.connection_connect(StatFilter.java:218) ~[druid-1.1.16.jar:1.1.16]
	at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:150) ~[druid-1.1.16.jar:1.1.16]
	at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1598) ~[druid-1.1.16.jar:1.1.16]
	at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1662) ~[druid-1.1.16.jar:1.1.16]
	at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2601) ~[druid-1.1.16.jar:1.1.16]
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

原因：根本就没有连接上数据库，连接超时、链接无效等意思

解决：

1、确定url链接、用户名、密码没有问题
2、确定用户名有权限，比如root用户有任何主机都可以连接的权限：参考
在这里插入图片描述
3、确认服务器防火墙中3306端口是开放的、或者关闭防火墙

查看防火墙状态 systemctl status firewalld
开启防火墙 systemctl start firewalld  
关闭防火墙 systemctl stop firewalld
开放指定端口 
firewall-cmd --zone=public --add-port=3306/tcp --permanent
重新载入开放端口 firewall-cmd --reload
移除指定端口 firewall-cmd --permanent --remove-port=3306/tcp