详解Struts2中对未登录jsp页面实现拦截功能

<filter>    <filter-name>SessionInvalidate</filter-name>    <filter-class>com.tp.action.SessionCheckFilter</filter-class> //过滤器核心类的class地址   <init-param>     <param-name>checkSessionKey</param-name> //session中需要检查的key    <param-value>users</param-value>    </init-param>    <init-param>     <param-name>redirectURL</param-name> //过滤重定向的地址    <param-value>/login.jsp</param-value>    </init-param>    <init-param>     <param-name>notCheckURLList</param-name> //不需要过滤的jsp    <param-value>/login.jsp</param-value>    </init-param>   </filter>   <filter-mapping>    <filter-name>SessionInvalidate</filter-name> //需要过滤的文件   <url-pattern>*.jsp</url-pattern>   </filter-mapping> 

package com.tp.action; import java.io.IOException;  import java.util.HashSet;  import java.util.Set;  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;  /**  * 用于检测用户是否登陆的过滤器，如果未登录，则重定向到指的登录页面 配置参数 checkSessionKey 需检查的在 Session 中保存的关键字  * redirectURL 如果用户未登录，则重定向到指定的页面，URL不包括 ContextPath notCheckURLList  * 不做检查的URL列表，以分号分开，并且 URL 中不包括 ContextPath  */  public class SessionCheckFilter implements Filter {   protected FilterConfig filterConfig = null;   private String redirectURL = null;   private Set<String> notCheckURLList = new HashSet<String>();   private String sessionKey = null;   @Override   public void destroy() {    notCheckURLList.clear();   }   @Override   public void doFilter(ServletRequest servletRequest,     ServletResponse servletResponse, FilterChain filterChain)     throws IOException, ServletException {    HttpServletRequest request = (HttpServletRequest) servletRequest;    HttpServletResponse response = (HttpServletResponse) servletResponse;    HttpSession session = request.getSession();    if (sessionKey == null) {     filterChain.doFilter(request, response);     return;    }    if ((!checkRequestURIIntNotFilterList(request))      && session.getAttribute("users") == null) {       response.sendRedirect(request.getContextPath() + redirectURL);     return;    }    filterChain.doFilter(servletRequest, servletResponse);   }   private boolean checkRequestURIIntNotFilterList(HttpServletRequest request) {    String uri = request.getServletPath()      + (request.getPathInfo() == null ? "" : request.getPathInfo());    String temp = request.getRequestURI();   temp = temp.substring(request.getContextPath().length() + 1);    // System.out.println("是否包括："+uri+";"+notCheckURLList+"=="+notCheckURLList.contains(uri));    return notCheckURLList.contains(uri);   }   @Override   public void init(FilterConfig filterConfig) throws ServletException {    this.filterConfig = filterConfig;    redirectURL = filterConfig.getInitParameter("redirectURL");    sessionKey = filterConfig.getInitParameter("checkSessionKey");    String notCheckURLListStr = filterConfig      .getInitParameter("notCheckURLList");    if (notCheckURLListStr != null) {     System.out.println(notCheckURLListStr);     String[] params = notCheckURLListStr.split(",");     for (int i = 0; i < params.length; i++) {      notCheckURLList.add(params[i].trim());     }    }   }  }