authenticationfilter.java

这段代码是用struts实现的客户管理系统

package com.tarena.filter;

import java.io.IOException;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.tarena.util.HttpFilter;

/**
 * 保护系统中的资源（/login.html和/login除外）,使只能被已经登录 的用户访问。
 * 
 * @author Allan
 */
public class AuthenticationFilter extends HttpFilter {
	@Override
	public void doFilter(HttpServletRequest request,
			HttpServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		HttpSession session = request.getSession();
		if (session.getAttribute("user") == null) {
			String path = request.getServletPath();
			if (!path.startsWith("/login")) {
				response.sendRedirect(request.getContextPath() + "/login.jsp");
				return;
			}
		}
		chain.doFilter(request, response);
	}
}