Java File Links

Unfortunately dealing with links and permissions is not really easily possible in java. At least with the following code you can figure out whether you dealing with a link or not. A similar piece code has recently been contributed to the commons-io project. Found that really useful and worth sharing.


public static boolean isLink( final File file ) throws IOException {
        if (file == null || !file.exists()) {
                return false;
        }

        return !file.getCanonicalFile().equals(file.getAbsoluteFile());
}

28. July 2008 | java

tcurdt

@Attila: Good catch! Thanks!
Attila Szegedi

This doesn't seem right. This function will also return true for a non-symlink file, if at least one of the directories in its path is symlinked.

This should work though:

File canonicalDir = file.getParentFile().getCanonicalFile();
File fileInCanonicalDir = new File(canonicalDir, file.getName());
return fileInCanonicalDir.getCanonicalFile().equals(fileInCanonicalDir.getAbsoluteFile());

Attila.
Steve Loughran

...something like this is marked as @since1.5 in the ant codebase. Its known to play up a bit on OS/X

Torsten Curdt’s weblog

Java File Links