eventhandlerbase.java

一个在线学习系统的服务端SERVLET程序

package eols.event.system;

import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;

import eols.tools.Log;

/**
 * <p>Title:事件处理基类</p>
 * <p>Description:完成事件处理的基本功能和框架
 * <p>所有事件处理器都必须继承自本类
 * <p>Copyright:(c) 2002</p>
 * @author Fasheng Qiu
 * @version 1.0
 */

public abstract class EventHandlerBase
{
    //事件处理标志
    //FAILEDED:表示处理失败
    //SUCCEED:表示处理成功
    protected final int FAILEDED = 0;
    protected final int SUCCEED = 1;

    //事件处理结果标量，初始值为处理失败
    protected int handleResult = FAILEDED;

    //读取属性文件类
    protected ResourceBundle bundle = null;

    //取得事件处理完毕后的转向页面的URL
    //该发放必须实现

    /**
     * 给定的默认的事件处理方法,一般继承需要重置本方法
     * @param sc 取得Servlet运行环境参数
     * @param request 用户请求对象
     * @param response 处理结果返回对象
     * @param beans 保存用户提交数据的散列表,即保存在多个bean中的数据
     * @throws IOException
     * @throws ServletException
     */
    public void process(ServletContext sc,
                        HttpServletRequest request,
                        HttpServletResponse response,
                        HashMap beans) throws IOException, ServletException
    {
        Log.log(this, "process", "Use default redirect method");
    }

    /**
     * 事物处理完毕后转向到结果显示页面
     * @param request 用户请求对象
     * @param response 处理结果返回对象
     * @throws IOException
     * @throws ServletException
     */
    public void forward(HttpServletRequest request,
                        HttpServletResponse response) throws IOException, ServletException
    {
        Log.log(this, "forward", "Use default redirect method");
        _dispatch(request, response);
    }

    /**
     * 转向到相应的显示页面显示处理结果
     * @param request 用户请求对象
     * @param response 处理结果返回对象
     * @throws IOException
     * @throws ServletException
     */
    protected void _dispatch(HttpServletRequest request,
                             HttpServletResponse response) throws IOException,
        ServletException
    {
        String url = "";

        //得到链接的信息(控制器中放入的sysFunction属性)
        eols.bean.system.SysFunction sysFunction =
            (eols.bean.system.SysFunction) request.getAttribute("sysFunction");
        url = sysFunction.getSysFunctionLink();

        Log.log(this, "_dispatch", "Redirect to: " + url);
        RequestDispatcher rd = request.getRequestDispatcher(url);
        if (rd == null)
        {
            Log.log(this, "_dispatch", "rd = null!");
        }
        rd.forward(request, response);
        }

    /**
     * 通过userID userPasswd role 进行权限控制
     * @param session 控制session
     * <p><b>需要做更改
     */

    protected void setSession(HttpServletRequest request, String role)
    {
        HttpSession session = request.getSession();
        session.setAttribute("user", request.getParameter("userID"));
        session.setAttribute("passwd", request.getParameter("userPasswd"));
        session.setAttribute("role", role);
    }
}