RFR: 8272120: Avoid looking for standard encodings in "java." modules

[Alan Bateman]

On Tue, 10 Aug 2021 05:08:54 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

> This is the continuation of JDK-8233884 and JDK-8271456. This change affects fewer cases so I fix all "java." modules at once.
> 
> In many places standard charsets are looked up via their names, for example:
> absolutePath.getBytes("UTF-8");
> 
> This could be done more efficiently(up to x20 time faster) with use of java.nio.charset.StandardCharsets:
> absolutePath.getBytes(StandardCharsets.UTF_8);
> 
> The later variant also makes the code cleaner, as it is known not to throw UnsupportedEncodingException in contrary to the former variant.
> 
> tested by the tier1/tier2/tier3 tests on Linux/Windows/macOS.

It would be useful to get up to date performance data on using Charset vs. charset name. At least historically, the charset name versions were faster (see [JDK-6764325](https://bugs.openjdk.java.net/browse/JDK-6764325)).

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PR: https://git.openjdk.java.net/jdk/pull/5063