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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   https://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.util;
17  
18  import io.netty.util.internal.InternalThreadLocalMap;
19  import static io.netty.util.internal.ObjectUtil.checkNotNull;
20  
21  import java.nio.charset.Charset;
22  import java.nio.charset.CharsetDecoder;
23  import java.nio.charset.CharsetEncoder;
24  import java.nio.charset.CodingErrorAction;
25  import java.util.Map;
26  
27  /**
28   * A utility class that provides various common operations and constants
29   * related with {@link Charset} and its relevant classes.
30   */
31  public final class CharsetUtil {
32  
33      /**
34       * 16-bit UTF (UCS Transformation Format) whose byte order is identified by
35       * an optional byte-order mark
36       */
37      public static final Charset UTF_16 = Charset.forName("UTF-16");
38  
39      /**
40       * 16-bit UTF (UCS Transformation Format) whose byte order is big-endian
41       */
42      public static final Charset UTF_16BE = Charset.forName("UTF-16BE");
43  
44      /**
45       * 16-bit UTF (UCS Transformation Format) whose byte order is little-endian
46       */
47      public static final Charset UTF_16LE = Charset.forName("UTF-16LE");
48  
49      /**
50       * 8-bit UTF (UCS Transformation Format)
51       */
52      public static final Charset UTF_8 = Charset.forName("UTF-8");
53  
54      /**
55       * ISO Latin Alphabet No. 1, as known as <tt>ISO-LATIN-1</tt>
56       */
57      public static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
58  
59      /**
60       * 7-bit ASCII, as known as ISO646-US or the Basic Latin block of the
61       * Unicode character set
62       */
63      public static final Charset US_ASCII = Charset.forName("US-ASCII");
64  
65      private static final Charset[] CHARSETS = new Charset[]
66              { UTF_16, UTF_16BE, UTF_16LE, UTF_8, ISO_8859_1, US_ASCII };
67  
68      public static Charset[] values() {
69          return CHARSETS;
70      }
71  
72      /**
73       * @deprecated Use {@link #encoder(Charset)}.
74       */
75      @Deprecated
76      public static CharsetEncoder getEncoder(Charset charset) {
77          return encoder(charset);
78      }
79  
80      /**
81       * Returns a new {@link CharsetEncoder} for the {@link Charset} with specified error actions.
82       *
83       * @param charset The specified charset
84       * @param malformedInputAction The encoder's action for malformed-input errors
85       * @param unmappableCharacterAction The encoder's action for unmappable-character errors
86       * @return The encoder for the specified {@code charset}
87       */
88      public static CharsetEncoder encoder(Charset charset, CodingErrorAction malformedInputAction,
89                                           CodingErrorAction unmappableCharacterAction) {
90          checkNotNull(charset, "charset");
91          CharsetEncoder e = charset.newEncoder();
92          e.onMalformedInput(malformedInputAction).onUnmappableCharacter(unmappableCharacterAction);
93          return e;
94      }
95  
96      /**
97       * Returns a new {@link CharsetEncoder} for the {@link Charset} with the specified error action.
98       *
99       * @param charset The specified charset
100      * @param codingErrorAction The encoder's action for malformed-input and unmappable-character errors
101      * @return The encoder for the specified {@code charset}
102      */
103     public static CharsetEncoder encoder(Charset charset, CodingErrorAction codingErrorAction) {
104         return encoder(charset, codingErrorAction, codingErrorAction);
105     }
106 
107     /**
108      * Returns a cached thread-local {@link CharsetEncoder} for the specified {@link Charset}.
109      *
110      * @param charset The specified charset
111      * @return The encoder for the specified {@code charset}
112      */
113     public static CharsetEncoder encoder(Charset charset) {
114         checkNotNull(charset, "charset");
115 
116         Map<Charset, CharsetEncoder> map = InternalThreadLocalMap.get().charsetEncoderCache();
117         CharsetEncoder e = map.get(charset);
118         if (e != null) {
119             e.reset().onMalformedInput(CodingErrorAction.REPLACE).onUnmappableCharacter(CodingErrorAction.REPLACE);
120             return e;
121         }
122 
123         e = encoder(charset, CodingErrorAction.REPLACE, CodingErrorAction.REPLACE);
124         map.put(charset, e);
125         return e;
126     }
127 
128     /**
129      * @deprecated Use {@link #decoder(Charset)}.
130      */
131     @Deprecated
132     public static CharsetDecoder getDecoder(Charset charset) {
133         return decoder(charset);
134     }
135 
136     /**
137      * Returns a new {@link CharsetDecoder} for the {@link Charset} with specified error actions.
138      *
139      * @param charset The specified charset
140      * @param malformedInputAction The decoder's action for malformed-input errors
141      * @param unmappableCharacterAction The decoder's action for unmappable-character errors
142      * @return The decoder for the specified {@code charset}
143      */
144     public static CharsetDecoder decoder(Charset charset, CodingErrorAction malformedInputAction,
145                                          CodingErrorAction unmappableCharacterAction) {
146         checkNotNull(charset, "charset");
147         CharsetDecoder d = charset.newDecoder();
148         d.onMalformedInput(malformedInputAction).onUnmappableCharacter(unmappableCharacterAction);
149         return d;
150     }
151 
152     /**
153      * Returns a new {@link CharsetDecoder} for the {@link Charset} with the specified error action.
154      *
155      * @param charset The specified charset
156      * @param codingErrorAction The decoder's action for malformed-input and unmappable-character errors
157      * @return The decoder for the specified {@code charset}
158      */
159     public static CharsetDecoder decoder(Charset charset, CodingErrorAction codingErrorAction) {
160         return decoder(charset, codingErrorAction, codingErrorAction);
161     }
162 
163     /**
164      * Returns a cached thread-local {@link CharsetDecoder} for the specified {@link Charset}.
165      *
166      * @param charset The specified charset
167      * @return The decoder for the specified {@code charset}
168      */
169     public static CharsetDecoder decoder(Charset charset) {
170         checkNotNull(charset, "charset");
171 
172         Map<Charset, CharsetDecoder> map = InternalThreadLocalMap.get().charsetDecoderCache();
173         CharsetDecoder d = map.get(charset);
174         if (d != null) {
175             d.reset().onMalformedInput(CodingErrorAction.REPLACE).onUnmappableCharacter(CodingErrorAction.REPLACE);
176             return d;
177         }
178 
179         d = decoder(charset, CodingErrorAction.REPLACE, CodingErrorAction.REPLACE);
180         map.put(charset, d);
181         return d;
182     }
183 
184     private CharsetUtil() { }
185 }