How do I get the local hostname if unresolvable through DNS in Java?

Question

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 r

Answer 1

Alternatively, use JNA to call the gethostname function on unixes, avoiding the reverse DNS lookup.

Some notes: on Linux, I believe gethostname simply calls uname and parses the output. On OS X the situation is more complex, as your hostname can be affected by DNS, but those side-effects aside, it's definitely what I get from hostname.

import com.sun.jna.LastErrorException
import com.sun.jna.Library
import com.sun.jna.Native

...

private static final C c = (C) Native.loadLibrary("c", C.class);

private static interface C extends Library {
    public int gethostname(byte[] name, int size_t) throws LastErrorException;
}

public String getHostName() {
    byte[] hostname = new byte[256];
    c.gethostname(hostname, hostname.length)
    return Native.toString(hostname)
}

jna-platform.jar includes Win32 functions, so there it's as simple as a call to Kernel32Util.getComputerName().