I did not know about the old HexDumpEncoder. It extends an internal
class `CharacterEncoder` which seems to be pretty similar purpose-wise
to what I am suggesting with CharsetEncoder. There is also the good old
`DatatypeConverter.printHexBinary`, though it can't stream.
But this is not really what I mean. The interesting part about doing
this as a charset is the unified API aspect of it, the fact that you can
reuse existing code utilizing Charset for hex operations.
- Jonas
On 05/02/2018 11:44 AM, Alan Bateman wrote:
On 02/05/2018 09:35, Jonas Konrad wrote:
Hi,
Conceptually, a 'charset' (in java) is a pair of transformations from
bytes to utf-16 code units and vice versa. Could it be useful to have
charset implementations that convert from bytes to the hex (or base64)
representations of those? The idea is as follows:
"0a0b0c".getBytes(HexCharset.getInstance()) = new byte[] { 0x0a, 0x0b,
0x0c }
new String(new byte[] { 0x0a, 0x0b, 0x0c }, HexCharset.getInstance())
= "0a0b0c"
The motivation behind this idea is that there are lots of APIs that
provide efficient transformations between chars and bytes using
charsets, but converting to/from hex for debugging is usually more
involved. One example of this is netty ByteBuf.toString (
https://netty.io/4.0/api/io/netty/buffer/ByteBuf.html#toString-int-int-java.nio.charset.Charset-
) - it would be really convenient to be able to just plug in a hex
charset to get nice debug output.
Of course this is only one example and there are other ways to get hex
output from ByteBuf in netty in particular, but I still think that a
hex charset would be an interesting tool to reuse code. I understand
this is a somewhat dubious use of a Charset, but I'd like to hear
other thoughts on it.
Have you looked at the Hex API proposed in JDK-8170769? It needs to be
dusted off but the last iteration discussed here got to the point where
it provides conversion of binary data to/from hex string representation.
It also supported both bulk and stream operations.
-Alan
