// Add the reference file to the zip file.
ZipFile zipFile = new ZipFile(file);
ZipParameters parameters = new ZipParameters();
parameters.setCompressionMethod(Zip4jConstants.COMP_DEFLATE);
parameters.setCompressionLevel(Zip4jConstants.DEFLATE_LEVEL_NORMAL);
zipFile.addFile(refFile, parameters);
httpHeaders.add("Content-Type", "application/zip");
httpHeaders.add("Content-Disposition",
"attachment; filename=\"" + file.getName() + "\"");
FileInputStream fis = new FileInputStream(file);