回复：Adding appendHex method to StringBuilder

[温绍锦(高铁)]

Using String Template FMT has better performance and better code readability. But String Template does not yet support for/while/if/switch. Is there any plan to enhance String Template to support for/while/if/switch? The following scenarios cannot be implemented using String.format or String Template. I think whether to build in support for foo(bar(x)) depends on whether it is a common enough method.
```java
package java.net;
class Inet6Address extends InetAddress {
 static String numericToTextFormat(byte[] src) {
 StringBuilder sb = new StringBuilder(39);
 for (int i = 0; i < (INADDRSZ / INT16SZ); i++) {
 sb.append(Integer.toHexString(((src[i<<1]<<8) & 0xff00)
 | (src[(i<<1)+1] & 0xff)));
 if (i < (INADDRSZ / INT16SZ) -1 ) {
 sb.append(":");
 }
 }
 return sb.toString();
 }
}
class SocketPermission {
 private boolean authorizedIPv6(String cname, byte[] addr) {
 String authHost = "";
 InetAddress auth;
 try {
 StringBuilder sb = new StringBuilder(39);
 for (int i = 15; i >= 0; i--) {
 sb.append(Integer.toHexString(((addr[i]) & 0x0f)));
 sb.append('.');
 sb.append(Integer.toHexString(((addr[i] >> 4) & 0x0f)));
 sb.append('.');
 }
 ...
 }
}
```
```java
package sun.security.krb5.internal.crypto.dk;
class DkCrypto {
 static String bytesToString(byte[] digest) {
 // Get character representation of digest
 StringBuilder digestString = new StringBuilder();
 for (int i = 0; i < digest.length; i++) {
 if ((digest[i] & 0x000000ff) < 0x10) {
 digestString.append('0').append(Integer.toHexString(digest[i] & 0x000000ff));
 } else {
 digestString.append(
 Integer.toHexString(digest[i] & 0x000000ff));
 }
 }
 return digestString.toString();
 }
}
```
- wenshao
------------------------------------------------------------------
发件人：Mark Reinhold <mark.reinhold at oracle.com>
发送时间：2023年10月2日(星期一) 20:19
收件人：Claes Redestad <claes.redestad at oracle.com>
抄　送：温绍锦(高铁) <shaojin.wensj at alibaba-inc.com>; core-libs-dev at openjdk.org <core-libs-dev at openjdk.org>
主　题：Re: Adding appendHex method to StringBuilder
2023/10/2 7:22:55 -0400, claes.redestad at oracle.com:
> I think this goes against the grain: StringBuilder is a simple builder
> for non-localized unformatted output. For formatted output there’s
> Formatter, String.format and, with JEP 430[1], FMT."..." to help output
> string data in more advanced, formatted and localized ways.
Agreed.
If we were to introduce a `fooBar(x)` method for every common
`foo(bar(x))` expression in the JDK code base then our APIs
would fast become inscrutable.
- Mark
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