Servlet filter inhibitor, usefull when you want to bypass an undesired filter sometimes.

FilterInhibitor.java

/* 
 */

package com.github.superbob.demo.servlets.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @author superbob
 *
 */
public class FilterInhibitor implements Filter {
    private static final Logger logger = LoggerFactory.getLogger(FilterInhibitor.class);

    private static final String FILTER_PARAM_CLASS = "inhibitor.filterClass";
    private static final String FILTER_PARAM_HEADER = "inhibitor.header";

    private static final String HEADER_DEFAULT = "Inhibit";

    private String header = HEADER_DEFAULT;

    private Filter filter;

    /* (non-Javadoc)
     * @see javax.servlet.Filter#destroy()
     */
    @Override
    public void destroy() {
        logger.info("Destroying filter inhibitor");
        logger.info("Destroying real filter");
        filter.destroy();
        logger.info("Destroyed !");
    }

    /* (non-Javadoc)
     * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
     */
    @Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1,
            FilterChain arg2) throws IOException, ServletException {
        if (allow(arg0, arg1, arg2)) {
            filter.doFilter(arg0, arg1, arg2);
        } else {
            arg2.doFilter(arg0, arg1);
        }
    }

    /* (non-Javadoc)
     * @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
     */
    @Override
    public void init(FilterConfig arg0) throws ServletException {
        logger.info("Initializing filter inhibitor");
        try {
            logger.info("Loading real filter : " + arg0.getInitParameter(FILTER_PARAM_CLASS));
            this.filter = (Filter) Class.forName(arg0.getInitParameter(FILTER_PARAM_CLASS)).newInstance();
        } catch (InstantiationException e) {
            logger.error("exception while initializing inhibitor filter", e);
            throw new RuntimeException(e);
        } catch (IllegalAccessException e) {
            logger.error("exception while initializing inhibitor filter", e);
            throw new RuntimeException(e);
        } catch (ClassNotFoundException e) {
            logger.error("ClassNotFoundException while initializing inhibitor filter, check your inhibitor filter configuration in web.xml and your classpath", e);
            throw new RuntimeException(e);
        }
        final String paramHeader = arg0.getInitParameter(FILTER_PARAM_HEADER);
        if (paramHeader != null) {
            this.header = paramHeader;
        }
        logger.info("Filtering on header : " + this.header);

        logger.info("Initializing real filter");
        filter.init(arg0);
        logger.info("Inhibitor engaged !");
    }

    private final boolean allow(ServletRequest arg0, ServletResponse arg1,
            FilterChain arg2) {
        if (HttpServletRequest.class.isAssignableFrom(arg0.getClass())) {
            HttpServletRequest httpReq = (HttpServletRequest) arg0;
            return !Boolean.parseBoolean(httpReq.getHeader(header));
        }
        return true;
    }

}

web.xml

<!-- Struts 2 -->
<!-- Struts 2 messes with file uploaded when using spring,
so an inhibitor is used to bypass its filtering when a given header is found in the request -->
<filter>
	<filter-name>struts2</filter-name>
	<filter-class>com.github.superbob.demo.servlets.filter.FilterInhibitor</filter-class>
	<!-- This is the real filter (struts2) -->
	<init-param>
	    <param-name>inhibitor.filterClass</param-name>
	    <param-value>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</param-value>
	</init-param>
	<!-- This is the header to look for, when it is set to true, the bypass will occur,
	otherwise the filter (struts2) will be called transparently -->
       <init-param>
           <param-name>inhibitor.header</param-name>
           <param-value>Inhibit</param-value>
       </init-param>
       <!-- All the specified parameters are transfered to the filter (struts2) initialization -->
	<init-param>
		<param-name>actionPackages</param-name>
		<param-value>com.github.superbob.demo.struts.actions</param-value>
	</init-param>
</filter>
<filter-mapping>
	<filter-name>struts2</filter-name>
	<url-pattern>*.action</url-pattern>
	<dispatcher>FORWARD</dispatcher>
	<dispatcher>REQUEST</dispatcher>
</filter-mapping>

I think this is an ingenious solution. With your permission, I tried to improve a bit to make it more reusable.

I also publish my code in github (https://github.com/evazquezma/JEE6/tree/master/wrapperFilter) and http://trabajosdesisifo.blogspot.com.es/2015/01/java-servlet-byapssfilter-filter.html.

Regards