import java.io.*;import java.lang.reflect.*;import java.security.*;import java.util.*;import javax.security.auth.*;import javax.security.auth.login.*;import javax.security.auth.callback.*;import javax.security.auth.spi.*;import javax.swing.*;/**   This login module authenticates users by reading usernames, passwords, and roles   from a text file. */public class SimpleLoginModule implements LoginModule{   public void initialize(Subject subject, CallbackHandler callbackHandler,       Map<String, ?> sharedState, Map<String, ?> options)   {      this.subject = subject;      this.callbackHandler = callbackHandler;      this.sharedState = sharedState;      this.options = options;   }   public boolean login() throws LoginException    {      if (callbackHandler == null)         throw new LoginException("no handler");      NameCallback nameCall = new NameCallback("username: ");      PasswordCallback passCall = new PasswordCallback("password: ", false);      try      {         callbackHandler.handle(new Callback[] { nameCall, passCall });               }      catch (UnsupportedCallbackException e)      {         LoginException e2 = new LoginException("Unsupported callback");         e2.initCause(e);         throw e2;      }      catch (IOException e)      {         LoginException e2 = new LoginException("I/O exception in callback");         e2.initCause(e);         throw e2;      }            return checkLogin(nameCall.getName(), passCall.getPassword());   }   /**      Checks whether the authentication information is valid. If it is, the subject acquires      principals for the user name and role.       @param username the user name       @param password a character array containing the password            @return true if the authentication information is valid   */   private boolean checkLogin(String username, char[] password) throws LoginException   {      try      {         Scanner in = new Scanner(new FileReader("" + options.get("pwfile")));         while (in.hasNextLine())         {            String[] inputs = in.nextLine().split("\\|");            if (inputs[0].equals(username) && Arrays.equals(inputs[1].toCharArray(), password))            {               String role = inputs[2];               Set<Principal> principals = subject.getPrincipals();               principals.add(new SimplePrincipal("username", username));               principals.add(new SimplePrincipal("role", role));               return true;            }         }         in.close();         return false;      }      catch (IOException e)      {         LoginException e2 = new LoginException("Can't open password file");         e2.initCause(e);         throw e2;      }   }   public boolean logout() { return true; }    public boolean abort() { return true; }    public boolean commit() { return true; }    private Subject subject;   private CallbackHandler callbackHandler;   private Map<String, ?> sharedState;   private Map<String, ?> options;}