Inside of Java web applications you can define chains of filters. So called servlet filters intercepts and transforms requests as well as responses. For example they can be used to define reject filters (IP or other request parameter based filters), for template decorators (sitemesh) or for first step configurations (Spring Log4JConfigurer).
public final class RejectFilter implements Filter {
public void doFilter(ServletRequest request,
ServletResponse response,
FilterChain chain)
throws IOException, ServletException {
String ipAddress = request.getRemoteAddr();
//only for internal access
if (ipAddress.startsWith("192.168.")) {
chain.doFilter(request, response);
}
}
Servlet filters will be configured in the web.xml file:
<filter> <filter-name>RejectFilter</filter-name> <filter-class>org.developers.blog.web.example.RejectFilter</filter-class> </filter> <filter-mapping> <filter-name>RejectFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>Regards
Rafael Sobek
Technorati Tags: Servlet Filter Servlet web.xml
