如果通过Java中的DNS无法解析，如何获取本地主机名？ [英] How do I get the local hostname if unresolvable through DNS in Java?

问题描述

这听起来像以前应该问过的东西，而且它有一些，但我希望获得机器的本地主机名和IP地址，即使它无法通过DNS解析（在Java中）。

This sounds like something that should have been asked before, and it has sort of, but I'm looking to get the local hostname and IP addresses of a machine even when it is not resolvable through DNS (in Java).

我可以通过迭代 NetworkInterfaces.getNetworkInterfaces（）来获得没有解决方案的本地IP地址。

I can get the local IP addresses without resolution by iterating through NetworkInterfaces.getNetworkInterfaces().

我发现这个问题的任何答案都表明要使用getLocalHost（）

Any answers to this question I've found indicate to use getLocalHost()

InetAddress localhost = java.net.InetAddress.getLocalHost();
hostName = localhost.getHostName();

但是如果主机名会抛出 UnknownHostException 无法通过DNS解析。

but this throws an UnknownHostException if the hostname isn't resolvable through DNS.

如果没有在幕后发现DNS查询，是否无法获取本地主机名？

Is there no way to get the local hostname without a DNS lookup happening behind the scenes?

编辑：检索到的IP地址是10.4.168.23
例外是 java.net.UnknownHostException：cms1.companyname.com：cms1.companyname.com （主机名已更改为伪匿名），并且hosts文件不包含主机名。但它知道它的主机名，所以我不确定为什么我不能在没有抛出异常的情况下得到它。

edit: the IP address retrieved is 10.4.168.23 The exception is java.net.UnknownHostException: cms1.companyname.com: cms1.companyname.com (hostname changed for pseudo-anonymity), and the hosts file does not contain the hostname. But it does know its hostname, so I'm not sure why I can't get it without an exception being thrown.

推荐答案

是的， 应该在Java中获取主机名而不使用名称服务查找，但遗憾的是没有。

Yes, there should be a way in Java to get the hostname without resorting to name service lookups but unfortunately there isn't.

但是，你可以这样做：

if (System.getProperty("os.name").startsWith("Windows")) {
    // Windows will always set the 'COMPUTERNAME' variable
    return System.getenv("COMPUTERNAME");
} else {
    // If it is not Windows then it is most likely a Unix-like operating system
    // such as Solaris, AIX, HP-UX, Linux or MacOS.

    // Most modern shells (such as Bash or derivatives) sets the 
    // HOSTNAME variable so lets try that first.
    String hostname = System.getenv("HOSTNAME");
    if (hostname != null) {
       return hostname;
    } else {

       // If the above returns null *and* the OS is Unix-like
       // then you can try an exec() and read the output from the 
       // 'hostname' command which exist on all types of Unix/Linux.

       // If you are an OS other than Unix/Linux then you would have 
       // to do something else. For example on OpenVMS you would find 
       // it like this from the shell:  F$GETSYI("NODENAME") 
       // which you would probably also have to find from within Java 
       // via an exec() call.

       // If you are on zOS then who knows ??

       // etc, etc
    }
}

<这将使您在传统的Sun JDK平台（Windows，Solaris，Linux）上获得100％的所需，但如果您的操作系统更加激动（从Java角度来看），则会变得不那么容易。请参阅代码示例中的注释。

and that will get you 100% what you want on the traditional Sun JDK platforms (Windows, Solaris, Linux) but becomes less easy if your OS is more excotic (from a Java perspective). See the comments in the code example.

我希望有更好的方法。

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