com.sun.grizzly.util.Charsets Maven / Gradle / Ivy
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package com.sun.grizzly.util;
import java.nio.charset.Charset;
import java.nio.charset.UnsupportedCharsetException;
import java.util.Locale;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
* Charset utility class.
*
* @author Alexey Stashok
*/
public final class Charsets {
static {
if (Boolean.getBoolean(Charsets.class.getName() + ".preloadAllCharsets")) {
preloadAllCharsets();
}
}
public static final String DEFAULT_CHARACTER_ENCODING = "ISO-8859-1";
private static final ConcurrentHashMap charsetAliasMap =
new ConcurrentHashMap();
public static final Charset ASCII_CHARSET = lookupCharset("ASCII");
public static final Charset UTF8_CHARSET = lookupCharset("UTF-8");
public static final Charset DEFAULT_CHARSET = lookupCharset(DEFAULT_CHARACTER_ENCODING);
private static volatile boolean areCharsetsPreloaded;
/**
* Lookup a {@link Charset} by name.
* Fixes Charset concurrency issue (http://paul.vox.com/library/post/the-mysteries-of-java-character-set-performance.html)
*
* @param charsetName
* @return {@link Charset}
*/
public static Charset lookupCharset(final String charsetName) {
final String charsetLowerCase = charsetName.toLowerCase(Locale.US);
Charset charset = charsetAliasMap.get(charsetLowerCase);
if (charset == null) {
if (areCharsetsPreloaded) {
// if all charsets are preloaded - throw Exception right away
throw new UnsupportedCharsetException(charsetName);
}
final Charset newCharset = Charset.forName(charsetLowerCase);
final Charset prevCharset =
charsetAliasMap.putIfAbsent(charsetLowerCase, newCharset);
charset = prevCharset == null ? newCharset : prevCharset;
}
return charset;
}
/**
* Preloads all JVM available {@link Charset}s, which makes charset search
* faster (for memory cost), especially non-existed charsets, because it
* lets us avoid pretty expensive {@link Charset#forName(java.lang.String)}
* call.
*/
public static void preloadAllCharsets() {
synchronized (charsetAliasMap) {
final Map charsetsMap = Charset.availableCharsets();
for (Charset charset : charsetsMap.values()) {
charsetAliasMap.put(
charset.name().toLowerCase(Locale.US), charset);
for (String alias : charset.aliases()) {
charsetAliasMap.put(alias.toLowerCase(Locale.US), charset);
}
}
areCharsetsPreloaded = true;
}
}
/**
* Removes all the charsets preloaded before.
*/
public static void drainAllCharsets() {
synchronized (charsetAliasMap) {
areCharsetsPreloaded = false;
charsetAliasMap.clear();
}
}
}