基于Filter的简单登录过滤器

public class LoginFilter implements Filter { private static List<String> exclude_uris = new ArrayList<String>(0); @Override public void destroy() { } @Override public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) resp; String uri = request.getRequestURI(); // 获取请求URL String path = uri + (request.getQueryString() != null ? "?" + request.getQueryString() : ""); // 获取上下文对象 String context = request.getContextPath(); HttpSession session = request.getSession(); // 获取session的sid String sid = session.toString().substring( session.toString().lastIndexOf("@") + 1); // 获取服务器全局对象 ServletContext application = session.getServletContext(); // 获取全局对象中的 上线用户列表 HashMap<String, String> onlines = (HashMap<String, String>) application .getAttribute("onlines"); if (onlines == null) { onlines = new HashMap<String, String>(0); } String loginid = null; if (session.getAttribute("loginid") != null) { loginid = session.getAttribute("loginid").toString(); } Object flag = session.getAttribute("islogin"); if (flag == null || !flag.toString().equals("1")) { // 未登录 if (exclude_uris.contains(path.replace(context + "/", "")) || path.indexOf(context + "/imgs/") != -1 || path.indexOf(context + "/css/") != -1 || path.indexOf(context + "/js/") != -1) { // 请求URL在不拦截列表，不拦截 chain.doFilter(request, response); } else { // 拦截请求，转发网页到login.jsp session.setAttribute("error", "请登录!"); response.sendRedirect(context + "/login.jsp"); } } else { // 已经登录 if (!onlines.containsKey(loginid) || !sid.equals(onlines.get(loginid))) { // 登录账号已经在先前登录 if (!exclude_uris.contains(path.replace(context + "/", "")) && path.indexOf(context + "/imgs/") == -1 && path.indexOf(context + "/css/") == -1 && path.indexOf(context + "/js/") == -1) { // 之前登录的相同账号被踢出 session.setAttribute("error", "您的账号在其他地方登录了!"); response.sendRedirect(context + "/login.jsp"); } else { chain.doFilter(request, response); } } else { chain.doFilter(request, response); } } } @Override public void init(FilterConfig fConfig) throws ServletException { String excludes = fConfig.getInitParameter("excludes"); String[] excludes_arr = excludes.split(","); for (String e : excludes_arr) { exclude_uris.add(e); } } }