防盗链代码

/** * 防盗链 * * @author fengjianhua */ public class HotlinkFilter implements Filter {  public void init(FilterConfig filterConfig) throws ServletException {  }  public void doFilter(ServletRequest req, ServletResponse resp,   FilterChain chain) throws IOException, ServletException {   HttpServletRequest request = (HttpServletRequest) req;   HttpServletResponse response = (HttpServletResponse) resp;   String referer = request.getHeader("referer");   if (referer == null || !referer.contains(request.getServerName())) {    request.getRequestDispatcher("/hotlink.gif").forward(request,response);   } else {    chain.doFilter(request, response);   }  }  public void destroy() {  } }