Aplicacion de Filtro

Filtro: validar.java

public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain)
throws IOException, ServletException {
RequestDispatcher rq=request.getRequestDispatcher("index.jsp");
HttpSession sesion=((HttpServletRequest) request).getSession();
Usuario u=(Usuario)sesion.getAttribute("user");
if(u==null){
rq.forward(request,response);
}
chain.doFilter(request, response);
}

Configuración del web.xml:


<filter>
<filter-name>validar</filter-name>
<filter-class>filtros.validar</filter-class>
</filter>
<filter-mapping>
<filter-name>validar</filter-name>
<url-pattern>/ventana_admin.jsp</url-pattern>
</filter-mapping>