usercontainer.java

我在加拿大学习的一个比较复杂的在线银行程序.

package com.ebusiness.ebank.security;

/**
 * <p>Title: </p>
 * <p>Description: This class acts as a global container to keep track of the
 *                  users in eBank system. When a new user uses the system first time,
 *                  the new user's information will be loaded and added to the container.
 *                  The user's information will be cached
 *                  in this object until it is removed on the scheduled time or
 *                  when the user's session is being destroyed.</p>
 * <p>Copyright: Copyright (c) 2005</p>
 * <p>Company:  eBusiness Inc., All right reserved</p>
 * @author unascribed
 * @version 1.0
 */

import java.util.HashSet;
import java.util.HashMap;
import java.util.Collections;
import java.util.Date;

import javax.servlet.http.HttpServletRequest;
import javax.ejb.SessionContext;

import com.ebusiness.ebank.exception.SystemException;

public class UserContainer
{
    private static HashMap container = new HashMap();
    private static String[] ebankRoles;

    private static long refreshInterval = 3600000 * 12; //default to 12 hour

    //This method is called by web tier
    public static UserProfile getUserProfile(HttpServletRequest request) throws SystemException
    {
        String userID = request.getRemoteUser();
        UserProfile user = (UserProfile)container.get(userID);
        if (user != null)
        {
            if (!needRefresh(user))
                return user;
        }

        HashSet roles = new HashSet();
        for (int i = 0; i < ebankRoles.length; i++)
        {
            if (request.isUserInRole(ebankRoles[i]))
                roles.add(ebankRoles[i]);
        }
        user = UserLoader.getInstance().load(userID, (String[])roles.toArray(new String[roles.size()]));
        container.put(userID, user);

        return user;
    }

    //This method is called by EJB tier
    public static UserProfile getUserProfile(SessionContext ctx) throws SystemException
    {
        String userID = ctx.getCallerPrincipal().getName();
        UserProfile user = (UserProfile)container.get(userID);
        if (user != null)
        {
            if (!needRefresh(user))
                return user;
        }

        HashSet roles = new HashSet();
        for (int i = 0; i < ebankRoles.length; i++)
        {
            if (ctx.isCallerInRole(ebankRoles[i]))
                roles.add(ebankRoles[i]);
        }
        user = UserLoader.getInstance().load(userID, (String[])roles.toArray(new String[roles.size()]));
        //user = new UserProfile(userID, (String[])roles.toArray(new String[roles.size()]));
        container.put(userID, user);

        return user;
    }

    /**
     * This method will only be called by sessionDestroyed method in a HttpSessionListener object,
     * to release user from the container when the user's session is being destroyed.
     * No other objects shall call this method
     */
    protected static void removeUser(String userID)
    {
        container.remove(userID);
    }

    //This method will only be called by a special object on a scheduled time
    //to release users and refresh the user's information. No other objects shall call this method
    protected static void removeAll()
    {
        container.clear();
    }

    //This method is called on the initialization of SignOnFilter
    protected static void initEbankRoles(String[] roles)
    {
        ebankRoles = roles;
    }

    //This method is called on the initialization of SignOnFilter
    protected static void initRefreshInterval(long interval)
    {
        refreshInterval = interval;
    }

    private static boolean needRefresh(UserProfile user)
    {
        Date currDate = new Date();
        return currDate.getTime() - user.getCreationDate().getTime() > refreshInterval;
    }
}