无法通过java代码更改文件夹的权限

Question

I create a temporary folder and then try to change its permission in my Windows 7 machine. I have admin privileges.

public class FilePermissionExample
{
    public static void main( String[] args )
    {
        try {

            File file = File.createTempFile("temp", Long.toString(System.nanoTime()));

            file.delete();
            file.mkdir();

            if(file.exists()){
                System.out.println("Is Execute allow : " + file.canExecute());
                System.out.println("Is Write allow : " + file.canWrite());
                System.out.println("Is Read allow : " + file.canRead());
            }


            file.setExecutable(false);
            file.setReadable(false);
            file.setWritable(false);

            System.out.println("Is Execute allow : " + file.canExecute());
            System.out.println("Is Write allow : " + file.canWrite());
            System.out.println("Is Read allow : " + file.canRead());

            if (file.createNewFile()){
                System.out.println("File is created!");
            }else{
                System.out.println("File already exists.");
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Output:
Is Execute allow : true
Is Write allow : true
Is Read allow : true
Is Execute allow : true
Is Write allow : true
Is Read allow : true
File already exists.

Expected:
Is Execute allow : true
Is Write allow : true
Is Read allow : true
Is Execute allow : false
Is Write allow : false
Is Read allow : false

I am facing a similar issue while writing hive test using hiverunner in windows. Can anyone suggest something?

Answer 1

From the API-documentation for java.io.File :

"A file system may implement restrictions to certain operations on the actual file-system object, such as reading, writing, and executing. These restrictions are collectively known as access permissions. The file system may have multiple sets of access permissions on a single object. For example, one set may apply to the object's owner, and another may apply to all other users. The access permissions on an object may cause some methods in this class to fail."

So your os doesn't allow to change the permissions.

Answer 2

If you want to change the permission on an NTFS formatted drive you need to change the permissions via the AclFileAttributeView .

Below quite verbose snippet shows the principal to remove the write permission for authorized users on a given file.

Assume the user jane is owner of the file fobar.bin and user john has as authorized user write permission to it. After running the snippet john could not write anymore to the file.

static final String AUTHENTICATED_USERS = "NT AUTHORITY\\Authenticated Users";

...

Path file = Paths.get("foobar.bin");
AclFileAttributeView view = Files.getFileAttributeView(
        file, AclFileAttributeView.class);

// show current permissions for authenticated users
for (AclEntry acl : view.getAcl()) {
    if (acl.principal().getName().equals(AUTHENTICATED_USERS)) {
        System.out.printf("current permissions: %s%n", acl.permissions());
    }
}

// remove the WRITE_DATA permission for authenticated users
// get list of current ACLs
List<AclEntry> acls = view.getAcl();
for (int i = 0; i < acls.size(); i++) {
    UserPrincipal principal = acls.get(i).principal();
    String principalName = principal.getName();
    if (principalName.equals(AUTHENTICATED_USERS)) {
        // get the current permissions
        Set<AclEntryPermission> permissions = acls.get(i).permissions();
        // remove WRITE_DATA permission
        permissions.remove(AclEntryPermission.WRITE_DATA);

        // create a new ACL entry
        AclEntry entry = AclEntry.newBuilder()
                .setType(AclEntryType.ALLOW)
                .setPrincipal(principal)
                .setPermissions(permissions)
                .build();

        // replace the ACL entry for authenticated users
        acls.set(i, entry);
    }
}
// set the updated list of ACLs
view.setAcl(acls);

// show updated permissions for authenticated users
for (AclEntry acl : view.getAcl()) {
    if (acl.principal().getName().equals(AUTHENTICATED_USERS)) {
        System.out.printf("updated permissions: %s%n", acl.permissions());
    }
}

example output (long lines wrapped)

current permissions: [READ_NAMED_ATTRS, DELETE, EXECUTE, WRITE_ACL, \
    WRITE_ATTRIBUTES, DELETE_CHILD, WRITE_DATA, READ_ATTRIBUTES, \
    SYNCHRONIZE, WRITE_OWNER, APPEND_DATA, WRITE_NAMED_ATTRS, READ_DATA, \
    READ_ACL]
updated permissions: [READ_NAMED_ATTRS, DELETE, EXECUTE, WRITE_ACL, \
    WRITE_ATTRIBUTES, DELETE_CHILD, READ_ATTRIBUTES, SYNCHRONIZE, \
    WRITE_OWNER, APPEND_DATA, WRITE_NAMED_ATTRS, READ_DATA, READ_ACL]

the permission WRITE_DATA has been removed.