判断用户是否登录，如果登录了放行，否则跳转到登陆页面

@H_607_5@package elkw.action; import javax.servlet.Filter; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.Servletrequest; import javax.servlet.ServletResponse; import javax.servlet.FilterChain; import java.io.IOException; import javax.servlet.http.httpServletrequest; import javax.servlet.http.httpSession; import javax.servlet.http.httpServletResponse; import elkw.po.system.User; public class RightFilter implements Filter { public void init(FilterConfig filterConfig) throws ServletException { } public void doFilter(Servletrequest request,ServletResponse response,FilterChain chain) throws IOException,ServletException { httpServletrequest req = (httpServletrequest) request; httpServletResponse res = (httpServletResponsE) response; httpSession session = req.getSession(true); //从session里取的用户名信息 User username = (User) session.getAttribute("user"); String reuris = req.getrequestuRI(); // 获取访问路径 String reuri = reuris.subString(0,17); //截取0-17的字符 String loginAction = "/BACkserver/login";//定义登陆的地址 //判断如果没有取到用户信息,就跳转到登陆@L_801_9@ String ipad = "/BACkserver/jsond"; if (username == null || "".equals(userName)) { //ipad请求数据和登陆@L_801_9@不过滤 if (reuri.equals(loginAction) || reuri.equals(ipad)) { chain.doFilter(request,responsE); return; } //跳转到登陆@L_801_9@ res.sendRedirect("http://"+req.getHeader("Host")+"/BACkserver"); } else { //已经登陆,继续此次请求 chain.doFilter(request,responsE); } } public void destroy() { } }

  下面配置这个过滤器 
  然后在web.xml里配置那些JSP文件需要登陆权限验证: 
 
 

<!-- 判断用户是否登录,过滤action的请求(你也可以写 (*.jsp),(*.html),(/*)全局的,)。。。。 -->
  <filter>  
          <filter-name>right</filter-name>  
          <filter-class>你的类名</filter-class>  
      </filter>  
  <filter-mapping>  
          <filter-name>right</filter-name>  
          <url-pattern>*.action</url-pattern><!-- 拦截-->
      </filter-mapping>

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