Grant Permission in Applet

Question

I am writing an applet which needed to read and write files with user's local machine, so i need to grant the permissions.
It seem the only way to grant the permissions for applets is needed user have some manually setup before running the applet. (Either modify the security policy
file or and add trust cert. ).
but i see some applets in the web and grant permission by a pop-up dialog
and user only need to answer "yes" or "no". how can they do this? is this supported by Java Plug-in? and How can i do it ??

Answer 1

Without policy file in your own class you can do this (i think NS only):
(import netscape.security.PrivilegeManager;)
try {
               PrivilegeManager.enablePrivilege("UniversalLinkAccess");
               System.out.println("\tUniversalLinkAccess Success!");
               PrivilegeManager.enablePrivilege("UniversalPropertyWrite");
               System.out.println("\tUniversalPropertyWrite Success!");
               PrivilegeManager.enablePrivilege("UniversalPropertyRead");
               System.out.println("\tUniversalPropertyRead Success!");
          } catch (netscape.security.ForbiddenTargetException e) {
               System.out.println(
                    "\tFailed! Permission to read system properties denied by user.");
          } catch (Exception e) {
               System.out.println("\tFailed! Unknown exception while enabling     privilege.");
               e.printStackTrace(System.out);
          }