mysql 应用程序连接到端口 3306 的问题
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Issue connecting to port 3306 for mysql application
提问by Walker Holahan
The Java application I am working with is supposed to write its resulting data to a mysql database, but whenever I run it, I get the following exception:
我正在使用的 Java 应用程序应该将其结果数据写入 mysql 数据库，但是每当我运行它时，我都会收到以下异常：
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
With the following cause:
由于以下原因：
Caused by: java.net.ConnectException: Connection refused
Naturally, my next step was to test the port that mysql was attempting to connect on (3306).
当然，我的下一步是测试 mysql 试图连接的端口 (3306)。
$ telnet localhost 3306
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection refused
My next step was to see if port 3306 was listening at all.
我的下一步是查看端口 3306 是否正在侦听。
$ netstat -an|grep 3306
tcp 0 0 69.164.214.18:3306 0.0.0.0:* LISTEN
So in summary, the port is listening but not accepting connections? I must admit, I do not know a whole lot about this, but does anybody know what is going on here?
总而言之，端口正在侦听但不接受连接？我必须承认，我对此知之甚少，但有人知道这里发生了什么吗？
采纳答案by Walker Holahan
I figured it out. I needed to connect to mysql externally, but my program was trying to access it locally.
我想到了。我需要从外部连接到 mysql，但我的程序试图在本地访问它。
回答by Go Namhyeon
Checklist:
清单：
- Firewall rule: If your server deny/not allow 3306 port, can not connect it.
- Bind Address: if your bind address are 127.0.0.1 in MySQL configuration, you must change to 0.0.0.0 in [mysqld] on /etc/mysql/my.cnf
- Restart Service: you have to run command 'service mysql restart'
- 防火墙规则：如果您的服务器拒绝/不允许 3306 端口，则无法连接。
- 绑定地址：如果你的绑定地址在 MySQL 配置中是 127.0.0.1，你必须在 /etc/mysql/my.cnf 上的 [mysqld] 中更改为 0.0.0.0
- 重新启动服务：您必须运行命令“service mysql restart”
Good Luck.
祝你好运。
