Log in Filter

1  Public classLoginfilterImplementsFilter {2      Public voiddestroy () {3 4     }5 6      Public voidDoFilter (servletrequest request, servletresponse response,7Filterchain chain)throwsIOException, servletexception {8         /*9 * 1. Get the user in sessionTen * 2. Determine if NULL One * > If NULL: Save error message, forward to msg.jsp A * > If NOT NULL: Release -          */ -HttpServletRequest req =(httpservletrequest) request; theObject user = Req.getsession (). getattribute ("Sessionuser"); -         if(User = =NULL) { -Req.setattribute ("Code", "error");//in order to display the X picture -Req.setattribute ("msg", "You are not logged in, please log in first"); +Req.getrequestdispatcher ("You want to jump to the landing page"). Forward (req, response); -}Else { +Chain.dofilter (request, response);//Release A         } at     } -  -      Public voidInit (Filterconfig fconfig)throwsservletexception { -  -     } -}

The Web. XML is configured as
<Filter>    <Display-name>Loginfilter</Display-name>    <Filter-name>Loginfilter</Filter-name>    <Filter-class>Filter class Path</Filter-class>  </Filter>  <filter-mapping>    <Filter-name>Loginfilter</Filter-name>    <Url-pattern>The page you want to filter</Url-pattern>  </filter-mapping>  <filter-mapping>    <Filter-name>Loginfilter</Filter-name>    <Servlet-name>The servlet you want to filter</Servlet-name>  </filter-mapping>  </filter-mapping>

Log in Filter