Servlet 过滤器Filter判断用户是否登陆（jsp页面）

来源：互联网发布：mac乐谱制作软件编辑：程序博客网时间：2024/06/05 22:44

过滤器Servlet类：

package servlet;import java.io.IOException;//import java.io.PrintWriter;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.RequestDispatcher;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 LoginFilter implements Filter { private static final String LOGON_URI = "LOGON_URI"; private static final String REGISTER_URI = "REGISTER_URI"; private String logon_page; private String register_page; public void destroy() { } public void doFilter(ServletRequest request, ServletResponse response,   FilterChain chain) throws IOException, ServletException {  HttpServletRequest req = (HttpServletRequest) request;  HttpServletResponse resp = (HttpServletResponse) response;  resp.setContentType("text/html;");  resp.setCharacterEncoding("utf-8");  HttpSession session = req.getSession(); // PrintWriter out = resp.getWriter();  // 得到用户请求的URI  String request_uri = req.getRequestURI();  // 得到web应用程序的上下文路径  String ctxPath = req.getContextPath();  // 去除上下文路径，得到剩余部分的路径  String uri = request_uri.substring(ctxPath.length());  // 判断用户访问的是否是登录页面  if (uri.equals(logon_page) || uri.equals(register_page)) {   chain.doFilter(request, response);   return;  } else {   // 如果访问的不是登录页面，则判断用户是否已经登录   if (null != session.getAttribute("curUser")     && "" != session.getAttribute("curUser")){    chain.doFilter(request, response);    return;   }    else {   String   msg = "您未登录！";           String  url = "Errorer";             req.setAttribute("err", msg);             RequestDispatcher dis = req.getRequestDispatcher(url);       dis.forward(req, resp);   }    //out.println("<script language=/"javaScript/">"     // + "parent.location.href='" +//ctxPath + logon_page + "'"    //  + "</script>");   // return;  // }  } } public void init(FilterConfig config) throws ServletException {  // TODO Auto-generated method stub  // 从部署描述符中获取登录页面和首页的URI  logon_page = config.getInitParameter(LOGON_URI);  register_page = config.getInitParameter(REGISTER_URI);  // System.out.println(logon_page);  if (null == logon_page || null == register_page) {   throw new ServletException("没有找到登录页面或主页");  } }}

修改Web核心配置文件：

注：保存后需要重启tomcat服务器

 <filter>    <filter-name>loginFilter</filter-name>    <filter-class>servlet.LoginFilter</filter-class>    <init-param>          <param-name>LOGON_URI</param-name>          <param-value>/login.jsp</param-value>    </init-param>    <init-param>          <param-name>REGISTER_URI</param-name>          <param-value>/register.jsp</param-value>    </init-param>  </filter><filter-mapping><filter-name>charseterEncodingFilter</filter-name><url-pattern>/*</url-pattern></filter-mapping> <filter-mapping>   <filter-name>loginFilter</filter-name>   <url-pattern>*.jsp</url-pattern>  </filter-mapping>

Errorer错误信息处理类：

package servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.RequestDispatcher;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class Error */public class Errorer extends HttpServlet {private static final long serialVersionUID = 1L;protected void processRequest(HttpServletRequest request, HttpServletResponse response)    throws ServletException, IOException {        response.setContentType("text/html;charset=UTF-8");        PrintWriter out = response.getWriter();        String url="login.jsp";        try {            out.println("<html>");            out.println("<head>");            out.println("<title>Servlet Error</title>");            out.println("</head>");            out.println("<body>");            out.println("<h2 align=center>" + request.getAttribute("err") + "</h2>");            response.setHeader("refresh", "2;url='login.jsp'");            response.setContentType("text/html;charset=UTF-8");            response.getWriter().write("请登录！页面将在3秒后自动跳转，如果没有，请点击<a href='login.jsp'>回到登录页面</a>");            out.println("</body>");            out.println("</html>");        } finally {            out.close();    RequestDispatcher dis = request.getRequestDispatcher(url);   dis.forward(request, response);        }    }    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">    /**      * Handles the HTTP <code>GET</code> method.     * @param request servlet request     * @param response servlet response     * @throws ServletException if a servlet-specific error occurs     * @throws IOException if an I/O error occurs     */    @Override    protected void doGet(HttpServletRequest request, HttpServletResponse response)    throws ServletException, IOException {        processRequest(request, response);    }     /**      * Handles the HTTP <code>POST</code> method.     * @param request servlet request     * @param response servlet response     * @throws ServletException if a servlet-specific error occurs     * @throws IOException if an I/O error occurs     */    @Override    protected void doPost(HttpServletRequest request, HttpServletResponse response)    throws ServletException, IOException {        processRequest(request, response);    }    /**      * Returns a short description of the servlet.     * @return a String containing servlet description     */    @Override    public String getServletInfo() {        return "Short description";    }// </editor-fold>}

效果展示：

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