Web page internal forwarding and URL input are different

1HttpServletRequest req=(httpservletrequest) request;2HttpServletResponse res=(httpservletresponse) response;3 4String Referer=req.getheader ("Referer");5         //If the referer is not empty6         if(referer!=NULL) //non-null instructions are internal forward access to other pages 7{//Release Resources8 Chain.dofilter (request, response);9         }Ten         //if Referer null is the direct enter key to access the servlet's One         Else A         { -SYSTEM.OUT.PRINTLN ("cannot be accessed directly"); -Response.setcontenttype ("Text/html;charset=utf-8"); the             //warning cannot be accessed directly -Response.getwriter (). Write ("" + -"<script>" + -"Window.alert (' You are trespassing, get out ');" + +"Window.location.href= ' http://127.0.0.1:8080/bbs/welcome.jsp '" + -"</script>"); +  A}