wro4j-core/src/main/java/ro/isdc/wro/http/GzipFilter.java
private void doGzipResponse(final HttpServletRequest req, final HttpServletResponse response, final FilterChain chain)
      throws IOException, ServletException {
    LOG.debug("Applying gzip on resource: " + req.getRequestURI());
    response.setHeader(HttpHeader.CONTENT_ENCODING.toString(), "gzip");
    final ByteArrayOutputStream baos = new ByteArrayOutputStream();
    final CountingOutputStream countingStream = new CountingOutputStream(new GZIPOutputStream(new BufferedOutputStream(
        baos)));
    // final GZIPOutputStream gzout = new GZIPOutputStream(new BufferedOutputStream(baos));
    // Perform gzip operation in-memory before sending response
    final HttpServletResponseWrapper wrappedResponse = new RedirectedStreamServletResponseWrapper(countingStream,
        response);
    chain.doFilter(req, wrappedResponse);
    // close underlying stream
    countingStream.close();
    response.setContentLength(countingStream.getCount());
    // avoid NO CONTENT error thrown by jetty when gzipping empty response
    if (countingStream.getCount() > 0) {
      IOUtils.write(baos.toByteArray(), response.getOutputStream());
    }
  }
private void doGzipResponse(final HttpServletRequest req, final HttpServletResponse response, final FilterChain chain)
      throws IOException, ServletException {
    LOG.debug("Applying gzip on resource: " + req.getRequestURI());
    response.setHeader(HttpHeader.CONTENT_ENCODING.toString(), "gzip");
    final ByteArrayOutputStream baos = new ByteArrayOutputStream();
    final CountingOutputStream countingStream = new CountingOutputStream(new GZIPOutputStream(new BufferedOutputStream(
        baos)));
    // final GZIPOutputStream gzout = new GZIPOutputStream(new BufferedOutputStream(baos));
    // Perform gzip operation in-memory before sending response
    final HttpServletResponseWrapper wrappedResponse = new RedirectedStreamServletResponseWrapper(countingStream,
        response);
    chain.doFilter(req, wrappedResponse);
    // close underlying stream
    countingStream.close();
    response.setContentLength(countingStream.getCount());
    // avoid NO CONTENT error thrown by jetty when gzipping empty response
    if (countingStream.getCount() > 0) {
      IOUtils.write(baos.toByteArray(), response.getOutputStream());
    }
  }
Performs actual gzip of the filtered content.