一个非常简单的登录权限拦截器，具体代码如下：
以下代码是继承OncePerRequestFilter实现登录过滤的代码：
/** * * @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); } } } 写完过滤器后，需要在web.xml中进行配置：
<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>
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