loginfilter.java

是一个基于java开发的拍卖系统 非常适合初学者看

package com.wish.jhk.util;

import java.io.IOException;
import java.util.Timer;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class LoginFilter implements Filter {

	// private FilterConfig filterConfig = null;

	public void init(FilterConfig filterConfig) throws ServletException {
		final Timer timer = new Timer();
		timer.scheduleAtFixedRate(new ItemUpdate(), 0, 1000 * 60 * 60);
	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		doFilter((HttpServletRequest) request, (HttpServletResponse) response,
				chain);
	} 

	public void doFilter(HttpServletRequest req, HttpServletResponse resp,
			FilterChain chain) throws IOException, ServletException {
		// HttpServletRequest req = (HttpServletRequest) request;
		// HttpServletResponse resp = (HttpServletResponse) response;
		HttpSession session = req.getSession(false);
		int userid = 0;
		if (session.getAttribute("userId") == null) {
			// 跳转到登陆页面
			// System.out.println(req.getHeader("referer"));
			// System.out.println(req.getHeader("Host"));
			// System.out.println(req.getContextPath());
			resp.sendRedirect("http://" + req.getHeader("Host")
					+ req.getContextPath() + "/login.jsp");
		} else {
			userid = (Integer) session.getAttribute("userId");
			// System.out.println(userid);
			if (userid == 0) {
				// 跳转到登陆页面
				resp.sendRedirect("http://" + req.getHeader("Host")
						+ req.getContextPath() + "/login.jsp");
			} else {
				// 已经登陆,继续此次请求
				// 传递过滤器
				chain.doFilter(req, resp);
			}
		}
	}
	public void destroy() {
	}

}