Servlet Filter

Question

Hi, all
I work on a web application running on a Jboss server and i would like to filter all the http request in order to save it in a database. (i save those informations for manage web stats).
I suppose i may use servlet filter, but i don't know the operation of this
Does anyone could help me giving some example and the protocol to set up this on the server (file server configuration as web.xml)

Answer 1

Well here is what I know. I hope it helps.....
First thing is to create a class that implements the "javax.servlet.Filter" interface. But there are also other Filter interfaces that you could use depending on what you want: Filter, FilterChain, and FilterConfig.
You have to implement the init(), destroy() and doFilter() methods (I ommitted the arguments).
But most of your work will be done in the doFilter () method. You could extract request information from one of the arguments in these method and have a datasource connection to save to your back-end.
Something like :
public void doFilter( ServletRequest request, ServletResponse responce, FilterChain chain ) throws  ServletException {
      HttpServletRequest httpRequest = (HttpServletRequest) request;
      backEndDelegate.saveInformation(  request.getRemoteAddr(),  request.getRemoteHost() );
      chain.doFilter( request, responce );
}Second, you need to configure the Filter. In the web.xml file add the following tags:
<filter>
     <filter-name>StatsFilter</filter-name>
      <description>Logs Web Stats to the back end</description>
     <filter-class>com.yourpackage.StatsFilter</filter-class>
     <!--  you can also pass parameters to the StatsFilter -->
      <!--
       <init-param>
               <param-name>some parameter</param-name>
               <param-value>some parameter</param-value>
        </init-param>
        -->
</filter>
<filter-mapping>
      <filter-name>StatsFilter</filter-name>
      <filter-pattern>*.jsp</filter-pattern>
</filter-mapping>That is just a little example. You can associate a filter with a Servlet using the <filter-mapping> tags too. And you can also do filter chains, but I don't feel like going there.
I sure hope that it was helpful. If not then "RTFM"