CODEWITHSUNDEEP
javawindowsmetadatanio
Mario
Mario

Reputation: 817

Get file owner metadata information with java

I am trying to retrieve the owner of a file, using this code: 

    Path file = Paths.get( fileToExtract.getAbsolutePath() );
    PosixFileAttributes attr = Files.readAttributes(file, PosixFileAttributes.class); //line that throws exception

    System.out.println(attr.owner.getName());

taken from oracle's page (http://docs.oracle.com/javase/tutorial/essential/io/fileAttr.html)

but i always get a UnsupportedOperationException at the line i indicate above.

java.lang.UnsupportedOperationException
at sun.nio.fs.WindowsFileSystemProvider.readAttributes(WindowsFileSystemProvider.java:192)
at java.nio.file.Files.readAttributes(Files.java:1684)

I think that 'readAttributes' method is abstract and this cause the exception, but (if this is true) i don't know how to implement this method in order to give me the file attributes.

Does anyone know how to implement this method, or an alternative method (that is tested) to get the file owner?

Upvotes: 4

Views: 11337

Answers (3)

user1328876
user1328876

Reputation:

Here is is a sample for files permissions on UNIX/Linux platforms

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.PosixFileAttributes;
import java.nio.file.attribute.PosixFilePermission;
import java.nio.file.attribute.PosixFilePermissions;
import java.util.Set;

class A { 
    public static void main(String[] args) throws Exception
    { 
        //Make sure file exists e.g. Unix path structure
       Path p = Paths.get("/a/b/Log.txt");
       PosixFileAttributes posix = Files.readAttributes(p,        
       PosixFileAttributes.class);

       //Set Permissions if needs be for the file Log.txt
       Set<PosixFilePermission> perms =   
           PosixFilePermissions.fromString("rw-r--r--");
       Files.setPosixFilePermissions(p, perms);

       //Output the various attributes of the file named Log.txt
       System.out.println(posix.group());
       System.out.println(posix.permissions());
       System.out.println(posix.owner());

    }
 }

Upvotes: 0

drkunibar
drkunibar

Reputation: 1337

Try this - works also on Windows

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.FileOwnerAttributeView;
import java.nio.file.attribute.UserPrincipal;

public class FileOwner {

    public static void main(String[] args) throws IOException {
        Path path = Paths.get("/tmp");
        FileOwnerAttributeView ownerAttributeView = Files.getFileAttributeView(path, FileOwnerAttributeView.class);
        UserPrincipal owner = ownerAttributeView.getOwner();
        System.out.println("owner: " + owner.getName());
    }

}

Upvotes: 12

Mena
Mena

Reputation: 48404

Use BasicFileAttributes instead. 

BasicFileAttributes attr = Files.readAttributes(file, BasicFileAttributes.class);

Posix file attributes are not supported in Windows.

Upvotes: 2

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