Examples of java.nio.file.attribute.UserPrincipal

java.nio.file.attribute.UserPrincipal

A {@code Principal} representing an identity used to determine access rightsto objects in a file system.

On many platforms and file systems an entity requires appropriate access rights or permissions in order to access objects in a file system. The access rights are generally performed by checking the identity of the entity. For example, on implementations that use Access Control Lists (ACLs) to enforce privilege separation then a file in the file system may have an associated ACL that determines the access rights of identities specified in the ACL.

A {@code UserPrincipal} object is an abstract representation of anidentity. It has a {@link #getName() name} that is typically the username oraccount name that it represents. User principal objects may be obtained using a {@link UserPrincipalLookupService}, or returned by {@link FileAttributeView} implementations that provide access to identity relatedattributes. For example, the {@link AclFileAttributeView} and {@link PosixFileAttributeView} provide access to a file's {@link PosixFileAttributes#owner owner}. @since 1.7

    UserPrincipalLookupService service = target.getFileSystem().getUserPrincipalLookupService();
    return new BlockingAction<Void>(handler) {
      public Void perform() {


        try {
          final UserPrincipal userPrincipal = user == null ? null : service.lookupPrincipalByName(user);
          final GroupPrincipal groupPrincipal = group == null ? null : service.lookupPrincipalByGroupName(group);
          if (groupPrincipal != null) {
            PosixFileAttributeView view = Files.getFileAttributeView(target, PosixFileAttributeView.class, LinkOption.NOFOLLOW_LINKS);
            if (view == null) {
              throw new FileSystemException("Change group of file not supported");

  public void testChownToOwnUser() throws Exception {
    String file1 = "some-file.dat";
    createFileWithJunk(file1, 100);
    String fullPath = testDir + pathSep + file1;
    Path path = Paths.get(fullPath);
    UserPrincipal owner = Files.getOwner(path);
    String user = owner.getName();
    vertx.fileSystem().chown(fullPath, user, null, ar -> {
      deleteFile(file1);
      assertTrue(ar.succeeded());
      testComplete();
    });

Examples of java.nio.file.attribute.UserPrincipal

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