Spring MVC过滤器-登录过滤的代码实现

/**  *  * @author geloin  * @date 2012-4-10 下午2:37:38  */ package com.test.spring.filter;  import java.io.IOException; import java.io.PrintWriter;  import javax.servlet.FilterChain; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;  import org.springframework.web.filter.OncePerRequestFilter;  /**  * 登录过滤  *  * @author geloin  * @date 2012-4-10 下午2:37:38  */ public class SessionFilter extends OncePerRequestFilter {    /*    * (non-Javadoc)    *    * @see    * org.springframework.web.filter.OncePerRequestFilter#doFilterInternal(    * javax.servlet.http.HttpServletRequest,    * javax.servlet.http.HttpServletResponse, javax.servlet.FilterChain)    */   @Override   protected void doFilterInternal(HttpServletRequest request,       HttpServletResponse response, FilterChain filterChain)       throws ServletException, IOException {      // 不过滤的uri     String[] notFilter = new String[] { "login.html", "index.html" };      // 请求的uri     String uri = request.getRequestURI();      // uri中包含background时才进行过滤     if (uri.indexOf("background") != -1) {       // 是否过滤       boolean doFilter = true;       for (String s : notFilter) {         if (uri.indexOf(s) != -1) {           // 如果uri中包含不过滤的uri，则不进行过滤           doFilter = false;           break;         }       }       if (doFilter) {         // 执行过滤         // 从session中获取登录者实体         Object obj = request.getSession().getAttribute("loginedUser");         if (null == obj) {           // 如果session中不存在登录者实体，则弹出框提示重新登录           // 设置request和response的字符集，防止乱码           request.setCharacterEncoding("UTF-8");           response.setCharacterEncoding("UTF-8");           PrintWriter out = response.getWriter();           String loginPage = "....";           StringBuilder builder = new StringBuilder();           builder.append("<script type=/"text/javascript/">");           builder.append("alert('网页过期，请重新登录！');");           builder.append("window.top.location.href='");           builder.append(loginPage);           builder.append("';");           builder.append("</script>");           out.print(builder.toString());         } else {           // 如果session中存在登录者实体，则继续           filterChain.doFilter(request, response);         }       } else {         // 如果不执行过滤，则继续         filterChain.doFilter(request, response);       }     } else {       // 如果uri中不包含background，则继续       filterChain.doFilter(request, response);     }   }  } 

<filter>   <filter-name>sessionFilter</filter-name>   <filter-class>com.test.spring.filter.SessionFilter</filter-class> </filter> <filter-mapping>   <filter-name>sessionFilter</filter-name>   <url-pattern>/*</url-pattern> </filter-mapping>