检测用户是否登陆的过滤器

Java code

  

   
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   import
    javax.servlet.
   *
   ; 
   import
    javax.servlet.http.HttpServletRequest; 
   import
    javax.servlet.http.HttpServletResponse; 
   import
    javax.servlet.http.HttpSession; 
   import
    java.util.List; 
   import
    java.util.ArrayList; 
   import
    java.util.StringTokenizer; 
   import
    java.io.IOException; 
   /**
    * 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
    CheckLoginFilter 
   implements
    Filter { 
   protected
    FilterConfig filterConfig 
   =
    
   null
   ; 
   private
    String redirectURL 
   =
    
   null
   ; 
   private
    List notCheckURLList 
   =
    
   new
    ArrayList(); 
   private
    String sessionKey 
   =
    
   null
   ; 
   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(sessionKey) 
   ==
    
   null
   ) { response.sendRedirect(request.getContextPath() 
   +
    redirectURL); 
   return
   ; } filterChain.doFilter(servletRequest, servletResponse); } 
   public
    
   void
    destroy() { notCheckURLList.clear(); } 
   private
    
   boolean
    checkRequestURIIntNotFilterList(HttpServletRequest request) { String uri 
   =
    request.getServletPath() 
   +
    (request.getPathInfo() 
   ==
    
   null
    
   ?
    
   ""
    : request.getPathInfo()); 
   return
    notCheckURLList.contains(uri); } 
   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
   ) { StringTokenizer st 
   =
    
   new
    StringTokenizer(notCheckURLListStr, 
   "
   ;
   "
   ); notCheckURLList.clear(); 
   while
   (st.hasMoreTokens()) { notCheckURLList.add(st.nextToken()); } } } }