userloginfilter.java

网上购书系统！jsp+servlet+jdbc实现！数据库sqlserver2

package myFiter;

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

public class UserLoginFilter extends HttpServlet implements Filter {
    private FilterConfig filterConfig;
    //Handle the passed-in FilterConfig
    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
    }

    //Process the request/response pair
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain filterChain) throws ServletException,
            IOException {
        HttpServletRequest httprequest = (HttpServletRequest) request;
        HttpServletResponse httpresponse = (HttpServletResponse) response;
        HttpSession session = httprequest.getSession();
        filterChain.doFilter(request, response);
        Object name = session.getAttribute("name");
        if (name == null) {
            httpresponse.sendRedirect("error.jsp");
        }

    }

    //Clean up resources
    public void destroy() {
    }
}