authorizationfactory.java

一套大型Office网络办公系统

/*
 * AuthorizationFactory.java
 *
 * Created on 2002年7月16日, 下午2:22
 */

package com.codefad.easyoffice;

/**
 *
 * @author  Chu daping
 */
public abstract class AuthorizationFactory {
    
    private static String className =
        "com.codefad.easyoffice.db.DbAuthorizationFactory";
    
    private static AuthorizationFactory factory = null;
    
    public static Authorization getAuthorization(String username,
            String password) throws UnauthorizedException
    {
        loadAuthorizationFactory();
        return factory.createAuthorization(username, password);
    }
    
    public static Authorization getAnonymousAuthorization() {
        loadAuthorizationFactory();
        return factory.createAnonymousAuthorization();
    }
    
    protected abstract Authorization createAuthorization(String username,
            String password) throws UnauthorizedException;
    
    protected abstract Authorization createAnonymousAuthorization();
    
    private static void loadAuthorizationFactory() {
        if (factory == null) {
            //Use className as a convenient object to get a lock on.
            synchronized(className) {
                    try {
                        Class c = Class.forName(className);
                        factory = (AuthorizationFactory)c.newInstance();
                    }
                    catch (Exception e) {
                        System.err.println("Exception loading class: " + e);
                        e.printStackTrace();
                    }
            }
        }
    }
}