1 /*
2 * Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package sun.nio.cs.ext;
27
28 import java.lang.ref.SoftReference;
29 import java.nio.charset.Charset;
30 import java.nio.charset.spi.CharsetProvider;
31 import java.util.ArrayList;
32 import java.util.TreeMap;
33 import java.util.Iterator;
34 import java.util.Locale;
35 import java.util.Map;
36 import sun.misc.ASCIICaseInsensitiveComparator;
37
38
39 /**
40 * Abstract base class for charset providers.
41 *
42 * @author Mark Reinhold
43 */
44
45 public class AbstractCharsetProvider
46 extends CharsetProvider
47 {
48
49 /* Maps canonical names to class names
50 */
51 private Map<String,String> classMap
52 = new TreeMap<>(ASCIICaseInsensitiveComparator.CASE_INSENSITIVE_ORDER);
53
54 /* Maps alias names to canonical names
55 */
56 private Map<String,String> aliasMap
57 = new TreeMap<>(ASCIICaseInsensitiveComparator.CASE_INSENSITIVE_ORDER);
58
59 /* Maps canonical names to alias-name arrays
60 */
61 private Map<String,String[]> aliasNameMap
62 = new TreeMap<>(ASCIICaseInsensitiveComparator.CASE_INSENSITIVE_ORDER);
63
64 /* Maps canonical names to soft references that hold cached instances
65 */
66 private Map<String,SoftReference<Charset>> cache
67 = new TreeMap<>(ASCIICaseInsensitiveComparator.CASE_INSENSITIVE_ORDER);
68
69 private String packagePrefix;
70
71 protected AbstractCharsetProvider() {
72 packagePrefix = "sun.nio.cs";
73 }
74
75 protected AbstractCharsetProvider(String pkgPrefixName) {
76 packagePrefix = pkgPrefixName;
77 }
78
79 /* Add an entry to the given map, but only if no mapping yet exists
80 * for the given name.
81 */
82 private static <K,V> void put(Map<K,V> m, K name, V value) {
83 if (!m.containsKey(name))
84 m.put(name, value);
85 }
86
87 private static <K,V> void remove(Map<K,V> m, K name) {
88 V x = m.remove(name);
89 assert (x != null);
90 }
91
92 /* Declare support for the given charset
93 */
94 protected void charset(String name, String className, String[] aliases) {
95 synchronized (this) {
96 put(classMap, name, className);
97 for (int i = 0; i < aliases.length; i++)
98 put(aliasMap, aliases[i], name);
99 put(aliasNameMap, name, aliases);
100 cache.clear();
101 }
102 }
103
104 protected void deleteCharset(String name, String[] aliases) {
105 synchronized (this) {
106 remove(classMap, name);
107 for (int i = 0; i < aliases.length; i++)
108 remove(aliasMap, aliases[i]);
109 remove(aliasNameMap, name);
110 cache.clear();
111 }
112 }
113
114 protected boolean hasCharset(String name) {
115 synchronized (this) {
116 return classMap.containsKey(name);
117 }
118 }
119
120 /* Late initialization hook, needed by some providers
121 */
122 protected void init() { }
123
124 private String canonicalize(String charsetName) {
125 String acn = aliasMap.get(charsetName);
126 return (acn != null) ? acn : charsetName;
127 }
128
129 private Charset lookup(String csn) {
130
131 // Check cache first
132 SoftReference<Charset> sr = cache.get(csn);
133 if (sr != null) {
134 Charset cs = sr.get();
135 if (cs != null)
136 return cs;
137 }
138
139 // Do we even support this charset?
140 String cln = classMap.get(csn);
141
142 if (cln == null)
143 return null;
144
145 // Instantiate the charset and cache it
146 try {
147
148 Class<?> c = Class.forName(packagePrefix + "." + cln,
149 true,
150 this.getClass().getClassLoader());
151
152 Charset cs = (Charset)c.newInstance();
153 cache.put(csn, new SoftReference<Charset>(cs));
154 return cs;
155 } catch (ClassNotFoundException x) {
156 return null;
157 } catch (IllegalAccessException x) {
158 return null;
159 } catch (InstantiationException x) {
160 return null;
161 }
162 }
163
164 public final Charset charsetForName(String charsetName) {
165 synchronized (this) {
166 init();
167 return lookup(canonicalize(charsetName));
168 }
169 }
170
171 public final Iterator<Charset> charsets() {
172
173 final ArrayList<String> ks;
174 synchronized (this) {
175 init();
176 ks = new ArrayList<>(classMap.keySet());
177 }
178
179 return new Iterator<Charset>() {
180 Iterator<String> i = ks.iterator();
181
182 public boolean hasNext() {
183 return i.hasNext();
184 }
185
186 public Charset next() {
187 String csn = i.next();
188 synchronized (AbstractCharsetProvider.this) {
189 return lookup(csn);
190 }
191 }
192
193 public void remove() {
194 throw new UnsupportedOperationException();
195 }
196 };
197 }
198
199 public final String[] aliases(String charsetName) {
200 synchronized (this) {
201 init();
202 return aliasNameMap.get(charsetName);
203 }
204 }
205
206 }