Java Reference
In-Depth Information
// Change the file owner to brice
UserPrincipal newOwner =
upls.lookupPrincipalByName("brice");
foav.setOwner(newOwner);
UserPrincipal changedOwner = foav.getOwner();
System.out.format("New owner of %s is %s%n",
path, changedOwner.getName());
}
catch (UnsupportedOperationException | IOException e) {
e.printStackTrace();
}
}
}
Original owner of C:\poems\luci1.txt is CORPORATE\ksharan
New owner of C:\poems\luci1.txt is CORPORATE\brice
The following snippet of code uses the
Files.setOwner()
method to update the owner of a file identified with
the path
C:\poems\luci1.txt
on Windows:
UserPrincipal owner = get the owner;
Path path = Paths.get("C:\\poems\\luci1.txt");
Files.setOwner(path, owner);
Managing ACL File Permissions
In this section, I will cover managing the file permissions using
AclFileAttributeView
. Note that ACL type file
attributes are supported on Microsoft Windows. An ACL consists of an ordered list of access control entries. Each
entry consists of a
UserPrincipal
, the type of access, and the level of the access to an object. In NIO.2, an instance of
the
AclEntry
class represents an entry in an ACL. You can get and set a
List
of
AclEntry
for a file using the
getAcl()
and
setAcl()
methods of the
AclFileAttributeView
. The following snippet of code gets the
List
of ACL entries for a
file called
C:\poems\luci1.txt
:
Path path = Paths.get("C:\\poems\\luci1.txt");
AclFileAttributeView view =
Files.getFileAttributeView(path, AclFileAttributeView.class);
List<AclEntry> aclEntries = view.getAcl();
The
AclEntry
class has methods to read various properties of an ACL entry. Its
principal()
method returns the
UserPrincipal
to identify the user or the group. Its
permissions()
method returns a
Set
of
AclEntryPermission
objects to identify the permissions. Its
type()
method returns an enum constant of the type
AclEntryType
such as
ALARM
,
ALLOW
,
AUDIT
, and
DENY
that indicates the type of the access. Its
flags()
method returns a
Set
of
AclEntryFlag
enum constants, which contains the inheritance flags of the ACL entry.
Listing 10-17 demonstrates how to read ACL entries for file
C:\poems\luci1.txt
. If the file does not exist, a
NoSuchFileException
is thrown. The program handles the exception and prints the stack trace of the exception. If you
run the program on a UNIX-like platform, it will print an error message that the ACL view is not supported. A partial
output is shown when the program was run on Windows. You may get a different output.
