RFR 8251989: Hex encoder and decoder utility

[Paul Sandoz]

Hi Roger,

A nice minimal addition. I agree with Mark’s naming suggestion.

- Use appropriate code convention for static field names.

- The encoder comes with two encoding production signatures, that returning a String and that for encoding into a StringBuilder.
The decoder comes with just one such production signature, returning byte[]. I imagine one might need a decode into a byte[] from a given offset.
Something to consider later if need be?

- More generally if there is pressure to add ByteBuffer accepting signatures we can punt and if necessary use MemorySegment once it exits incubating.


>  36  * Utilities to encode bytes to hex strings and decode hex strings to bytes.


I recommend using “hexadecimal (hex)” for the first use, and “hex” thereafter.


>  48  * For example, for a comma (",") separated format with a prefix and suffix


Use an @apiNote


>  63  *     Hex.Encoder encodeFingerprint = Hex.encoder(":", "", "",true);


Missing space after last comma.


>  60  * RFC 4752 defines a fingerprint of byte values that uses the delimiter colon {@code ':'}.
>  61  * The encoder and decoder for RFC 2752 are:


s/2752/4752 ?


> 254         public StringBuilder encodeHexPair(StringBuilder sb, int value) {


This can be specified as behaving as if sb.append(toHexPair(value)), and also say @see #toHexPair.

Paul.

> On Aug 19, 2020, at 2:14 PM, Roger Riggs <Roger.Riggs at oracle.com> wrote:
> 
> Please review a java.util.Hex API to encode and decode hexadecimal strings to and from byte arrays.
> 
> Within the JDK and JDK tests there are multiple implementations to encode and decode
> hexadecimal strings to byte arrays. Hex encoders and decoders support
> upper or lower case hexadecimal characters, delimiters, prefix, and suffix.
> The API is modeled after the java.util.Base64 API providing static factories,
> immutable threadsafe instances with methods to encode to and decode from
> string and StringBuilder.
> 
> JavaDoc:
> http://cr.openjdk.java.net/~rriggs/hex-javadoc/java.base/java/util/Hex.html
> 
> Webrev for Hex encoder and decoder:
>    http://cr.openjdk.java.net/~rriggs/webrev-hex-encoder-8251989
> 
> Webrev for applying to java.security:
>    http://cr.openjdk.java.net/~rriggs/webrev-hex-security-8252055
> 
> CSR:
>    https://bugs.openjdk.java.net/browse/JDK-8251991
> 
> Issue for API and a few uses:
>    https://bugs.openjdk.java.net/browse/JDK-8251989
> 
> Issue for Use in java.security and tests:
>    https://bugs.openjdk.java.net/browse/JDK-8252055
>