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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    *   http://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 org.jboss.netty.util;
    17
    18  import java.nio.charset.Charset;
    19  import java.nio.charset.CharsetDecoder;
    20  import java.nio.charset.CharsetEncoder;
    21  import java.nio.charset.CodingErrorAction;
    22  import java.util.IdentityHashMap;
    23  import java.util.Map;
    24
    25  /**
    26   * A utility class that provides various common operations and constants
    27   * related with {@link Charset} and its relevant classes.
    28   */
    29  public final class CharsetUtil {
    30
    31      /**
    32       * 16-bit UTF (UCS Transformation Format) whose byte order is identified by
    33       * an optional byte-order mark
    34       */
    35      public static final Charset UTF_16 = Charset.forName("UTF-16");
    36
    37      /**
    38       * 16-bit UTF (UCS Transformation Format) whose byte order is big-endian
    39       */
    40      public static final Charset UTF_16BE = Charset.forName("UTF-16BE");
    41
    42      /**
    43       * 16-bit UTF (UCS Transformation Format) whose byte order is little-endian
    44       */
    45      public static final Charset UTF_16LE = Charset.forName("UTF-16LE");
    46
    47      /**
    48       * 8-bit UTF (UCS Transformation Format)
    49       */
    50      public static final Charset UTF_8 = Charset.forName("UTF-8");
    51
    52      /**
    53       * ISO Latin Alphabet No. 1, as known as <tt>ISO-LATIN-1</tt>
    54       */
    55      public static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
    56
    57      /**
    58       * 7-bit ASCII, as known as ISO646-US or the Basic Latin block of the
    59       * Unicode character set
    60       */
    61      public static final Charset US_ASCII = Charset.forName("US-ASCII");
    62
    63      private static final ThreadLocal<Map<Charset, CharsetEncoder>> encoders =
    64          new ThreadLocal<Map<Charset, CharsetEncoder>>() {
    65              @Override
    66              protected Map<Charset, CharsetEncoder> initialValue() {
    67                  return new IdentityHashMap<Charset, CharsetEncoder>();
    68              }
    69          };
    70
    71      private static final ThreadLocal<Map<Charset, CharsetDecoder>> decoders =
    72          new ThreadLocal<Map<Charset, CharsetDecoder>>() {
    73              @Override
    74              protected Map<Charset, CharsetDecoder> initialValue() {
    75                  return new IdentityHashMap<Charset, CharsetDecoder>();
    76              }
    77          };
    78
    79      /**
    80       * Returns a cached thread-local {@link CharsetEncoder} for the specified
    81       * <tt>charset</tt>.
    82       */
    83      public static CharsetEncoder getEncoder(Charset charset) {
    84          if (charset == null) {
    85              throw new NullPointerException("charset");
    86          }
    87
    88          Map<Charset, CharsetEncoder> map = encoders.get();
    89          CharsetEncoder e = map.get(charset);
    90          if (e != null) {
    91              e.reset();
    92              e.onMalformedInput(CodingErrorAction.REPLACE);
    93              e.onUnmappableCharacter(CodingErrorAction.REPLACE);
    94              return e;
    95          }
    96
    97          e = charset.newEncoder();
    98          e.onMalformedInput(CodingErrorAction.REPLACE);
    99          e.onUnmappableCharacter(CodingErrorAction.REPLACE);
    100         map.put(charset, e);
    101         return e;
    102     }
    103
    104     /**
    105      * Returns a cached thread-local {@link CharsetDecoder} for the specified
    106      * <tt>charset</tt>.
    107      */
    108     public static CharsetDecoder getDecoder(Charset charset) {
    109         if (charset == null) {
    110             throw new NullPointerException("charset");
    111         }
    112
    113         Map<Charset, CharsetDecoder> map = decoders.get();
    114         CharsetDecoder d = map.get(charset);
    115         if (d != null) {
    116             d.reset();
    117             d.onMalformedInput(CodingErrorAction.REPLACE);
    118             d.onUnmappableCharacter(CodingErrorAction.REPLACE);
    119             return d;
    120         }
    121
    122         d = charset.newDecoder();
    123         d.onMalformedInput(CodingErrorAction.REPLACE);
    124         d.onUnmappableCharacter(CodingErrorAction.REPLACE);
    125         map.put(charset, d);
    126         return d;
    127     }
    128
    129     private CharsetUtil() {
    130         // Unused
    131     }
    132 }