StatelessAuthenticationFilter.java

package com.jdriven.stateless.security;

import java.io.IOException;

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

import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.web.filter.GenericFilterBean;

class StatelessAuthenticationFilter extends GenericFilterBean {

	private final TokenAuthenticationService tokenAuthenticationService;

	protected StatelessAuthenticationFilter(TokenAuthenticationService taService) {
		this.tokenAuthenticationService = taService;
	}

	@Override
	public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException,
			ServletException {
		SecurityContextHolder.getContext().setAuthentication(
				tokenAuthenticationService.getAuthentication((HttpServletRequest) req));
		chain.doFilter(req, res); // always continue
	}
}