Here's the main application program (the one called from the command line) for this example. It instantiates a login context, logs in, tries to execute two sensitive objects (one using programmatic authorization, the other using declarative authorization), and then logs out. Next, we'll look more closely at two elements of the main program: programmatic authorization and declarative authorization.

import java.security.*;
import javax.security.auth.*;
import javax.security.auth.callback.*;
import javax.security.auth.login.*;
//
// This is the main program in the JAAS Example.  It creates a Login  
// Context, logs the user in based on the settings in the Login  
// Configuration file,and calls two sensitive pieces of code, the  
// first using programmatic authorization, and the second using 
// declarative authorization.
public class JAASExample {

     static LoginContext lc = null;

     public static void main( String[] args) {
       //
       // Create a login context
       try {
         lc = new LoginContext("JAASExample",
            new UsernamePasswordCallbackHandler());
       } catch (LoginException le) {
         System.out.println( "Login Context Creation Error" );
         System.exit(1);
       }
       //

       // Login
       try {
         lc.login();
       } catch (LoginException le) {
         System.out.println( "\nOVERALL AUTHENTICATION FAILED\n" );
         System.exit(1);
       }
       System.out.println( "\nOVERALL AUTHENTICATION SUCCEEDED\n" );
       System.out.println( lc.getSubject() );
       //
       // Call the sensitive PayrollAction code, which uses programmatic
       // authorization.
       try {
         Subject.doAs( lc.getSubject(), new PayrollAction() );
       } catch (AccessControlException e) {
         System.out.println( "Payroll Access DENIED" );
       }
       //
       // Call the sensitive PersonnelAction code, which uses declarative
       // authorization.
       try {
         Subject.doAsPrivileged( lc.getSubject(), new PersonnelAction(), null );
       } catch (AccessControlException e) {
         System.out.println( "Personnel Access DENIED" );
       }
       try {
         lc.logout();
       } catch (LoginException le) {
         System.out.println( "Logout FAILED" );
         System.exit(1);
       }
       System.exit(0);

     }
}