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package sun.nio.cs;

import java.lang.ref.SoftReference;
import java.nio.charset.Charset;
import java.nio.charset.spi.CharsetProvider;
import java.util.ArrayList;
import java.util.TreeMap;
import java.util.Iterator;
import java.util.Locale;
import java.util.Map;
import sun.misc.ASCIICaseInsensitiveComparator;


Abstract base class for charset providers.
Author:Mark Reinhold
/** * Abstract base class for charset providers. * * @author Mark Reinhold */
public class AbstractCharsetProvider extends CharsetProvider { /* Maps canonical names to class names */ private Map<String,String> classMap = new TreeMap<>(ASCIICaseInsensitiveComparator.CASE_INSENSITIVE_ORDER); /* Maps alias names to canonical names */ private Map<String,String> aliasMap = new TreeMap<>(ASCIICaseInsensitiveComparator.CASE_INSENSITIVE_ORDER); /* Maps canonical names to alias-name arrays */ private Map<String,String[]> aliasNameMap = new TreeMap<>(ASCIICaseInsensitiveComparator.CASE_INSENSITIVE_ORDER); /* Maps canonical names to soft references that hold cached instances */ private Map<String,SoftReference<Charset>> cache = new TreeMap<>(ASCIICaseInsensitiveComparator.CASE_INSENSITIVE_ORDER); private String packagePrefix; protected AbstractCharsetProvider() { packagePrefix = "sun.nio.cs"; } protected AbstractCharsetProvider(String pkgPrefixName) { packagePrefix = pkgPrefixName; } /* Add an entry to the given map, but only if no mapping yet exists * for the given name. */ private static <K,V> void put(Map<K,V> m, K name, V value) { if (!m.containsKey(name)) m.put(name, value); } private static <K,V> void remove(Map<K,V> m, K name) { V x = m.remove(name); assert (x != null); } /* Declare support for the given charset */ protected void charset(String name, String className, String[] aliases) { synchronized (this) { put(classMap, name, className); for (int i = 0; i < aliases.length; i++) put(aliasMap, aliases[i], name); put(aliasNameMap, name, aliases); cache.clear(); } } protected void deleteCharset(String name, String[] aliases) { synchronized (this) { remove(classMap, name); for (int i = 0; i < aliases.length; i++) remove(aliasMap, aliases[i]); remove(aliasNameMap, name); cache.clear(); } } /* Late initialization hook, needed by some providers */ protected void init() { } private String canonicalize(String charsetName) { String acn = aliasMap.get(charsetName); return (acn != null) ? acn : charsetName; } private Charset lookup(String csn) { // Check cache first SoftReference<Charset> sr = cache.get(csn); if (sr != null) { Charset cs = sr.get(); if (cs != null) return cs; } // Do we even support this charset? String cln = classMap.get(csn); if (cln == null) return null; // Instantiate the charset and cache it try { Class<?> c = Class.forName(packagePrefix + "." + cln, true, this.getClass().getClassLoader()); Charset cs = (Charset)c.newInstance(); cache.put(csn, new SoftReference<Charset>(cs)); return cs; } catch (ClassNotFoundException x) { return null; } catch (IllegalAccessException x) { return null; } catch (InstantiationException x) { return null; } } public final Charset charsetForName(String charsetName) { synchronized (this) { init(); return lookup(canonicalize(charsetName)); } } public final Iterator<Charset> charsets() { final ArrayList<String> ks; synchronized (this) { init(); ks = new ArrayList<>(classMap.keySet()); } return new Iterator<Charset>() { Iterator<String> i = ks.iterator(); public boolean hasNext() { return i.hasNext(); } public Charset next() { String csn = i.next(); synchronized (AbstractCharsetProvider.this) { return lookup(csn); } } public void remove() { throw new UnsupportedOperationException(); } }; } public final String[] aliases(String charsetName) { synchronized (this) { init(); return aliasNameMap.get(charsetName); } } }