checkuserfilter.java

在线考试系统的具体实现 利用JSP+myeclipse6.6+tomcat5。5.27

package org.mmxbb.exam.business;

import java.io.IOException;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;



public class CheckUserFilter
    extends HttpServlet
    implements javax.servlet.Filter {
  private FilterConfig filterConfig;
  final String LOGIN_PAGE = "../index.jsp";

 
  public void init(FilterConfig filterConfig) throws ServletException {
    this.filterConfig = filterConfig;
  }

  public void setFilterConfig(final FilterConfig filterConfig) {
    this.filterConfig = filterConfig;
  }


  public void doFilter(ServletRequest request, ServletResponse response,
                       FilterChain filterChain) {

    HttpServletRequest hreq = (HttpServletRequest) request;
    HttpServletResponse hres = (HttpServletResponse) response;
    HttpSession session = hreq.getSession();
    if ( (session != null) && (session.getAttribute("logon") != null)) {
      LogonBean logonBean = (LogonBean) session.getAttribute("logon");
      if (!logonBean.isAuthority()) {
        try {
          filterChain.doFilter(request, response);
        } catch (ServletException ex) {
          ex.printStackTrace();
        } catch (IOException ex) {
          ex.printStackTrace();
        }
        return;
      }
    } else {
      try {
        hres.sendRedirect(LOGIN_PAGE);
      } catch (IOException ex1) {
        ex1.printStackTrace();
      }
    }
  }

 
  public void destroy() {
    this.filterConfig = null;
  }
}