Filter Requests with JEE 6 / 7

2015-01-15

A tiny but shiny improvement with Java EE 6 was the @WebFilter – Annotation which made the filtering and manipulating of requests very easy: No more com.sun.jersey.spi.container.ContainerResponseFilters entries in the web.xml.

All you have to do is to implements the Filter-Interface and annotate your class:

package com.fpm.playground.internal.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;

@WebFilter("/*")
public class CacheFilter implements Filter {

  @Override
  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain){
    try {

      // manipulate response

      chain.doFilter(request, response);

    } catch (IOException e) {
      //TODO handle exception

    } catch (ServletException e) {
      //TODO handle exception
    }
  }

  @Override
  public void init(FilterConfig filterConfig) throws ServletException {

  }

  @Override
  public void destroy() {
  }

}

With this solutions it’s very easy to enable CORS in REST-Requests or seperatly cache some resources while others have to refresh every request.