问题描述
我有这个用 Java 编写的俄罗斯方块游戏，它使用 DB 来记录高分.只要我使用远程 MySQL 数据库，它就可以正常工作，但现在我正在尝试使用 XAMPP MySQL 设置 localhost 数据库，并且它在命令中一直像SQLException:通信链接失败"一样:
I have this Tetris game written in Java, which uses DB to record high scores. It worked ok as long as I was using remote MySQL DB, but now I'm trying to set up localhost DB using XAMPP MySQL and it keeps going like "SQLException: Communications link failure" at command:
con = java.sql.DriverManager.getConnection("jdbc:mysql://localhost/score", user, psw);
我猜是错误的 URL 或数据库配置，但我真的不知道要检查什么.有什么想法吗?
I guess it's either wrong URL or DB configuration, but I really don't know what to check. Any ideas?
我的朋友解决了我的问题，将 URL 中的localhost"替换为127.0.0.1"(这很尴尬，你可以想象 :P).
My friend has fixed my problem by replacing "localhost" in URL by "127.0.0.1" (which was quite embarrassing as you can surely imagine :P ).
所以问题是:为什么 XAMPP 无法将localhost"转换为 IP 地址以及如何解决?
推荐答案
为什么 XAMPP 无法将localhost"翻译成 IP 地址以及如何解决?
这不是 XAMPP 问题，也不是编程问题.这更像是一个 DNS 问题.
This is not a XAMPP problem nor a programming problem. This is more a DNS problem.
首先，您是否有一个 %SystemRoot%/system32/drivers/etc/hosts 文件，其中以下行作为 first 行?(因此，在所有评论之后，但在任何其他主机声明之前)
To start, do you have a %SystemRoot%/system32/drivers/etc/hosts file with the following line as first line? (thus, after all comments, but before any other host declarations)
127.0.0.1 localhost
更新: 根据我的评论 谷歌了一下，看起来 MySQL JDBC 驱动程序不吃 IPv6地址.换句话说，您需要将 ::1 更改为 127.0.0.1.但是我也发现 this topic 里面提到可以使用下面的JVM解决这个问题的论据:
Update: as per the comments I've Googled a bit and it look like that the MySQL JDBC driver doesn't eat IPv6 addresses at all. In other words, you'll need to change ::1 to 127.0.0.1. But I also found this topic which mentions that you can use the following JVM argument to fix this problem:
java -Djava.net.preferIPv4Stack=true
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