/**
* Read first {@code sniffLength} bytes of {@code resource}'s payload, decoding {@code
* Content-Encoding} if any. Reset {@code resource}'s read position back to zero.
*
* @param resource Resource to load bytes from
* @return bytes, zero-padded if payload is shorter.
* @throws IOException
*/
protected byte[] peekContent(Resource resource) throws IOException {
byte[] bbuffer = new byte[Math.max(sniffLength, MINIMUM_SNIFF_BUFFER_SIZE)];
String encoding = resource.getHeader("content-encoding");
if ("gzip".equalsIgnoreCase(encoding) || "x-gzip".equalsIgnoreCase(encoding)) {
// use larger readlimit, because gzip-ed data can be larger than the original
// at low compression level.
resource.mark(sniffLength + 100);
@SuppressWarnings("resource")
Resource z = new GzipDecodingResource(resource);
z.read(bbuffer, 0, sniffLength);
resource.reset();
} else {
resource.mark(sniffLength);
resource.read(bbuffer, 0, sniffLength);
resource.reset();
}
return bbuffer;
}
