    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.codec;
    018
    019import java.nio.charset.Charset;
    020
    021/**
    022 * Charsets required of every implementation of the Java platform.
    023 *
    024 * From the Java documentation <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard
    025 * charsets</a>:
    026 * <p>
    027 * <cite>Every implementation of the Java platform is required to support the following character encodings. Consult the
    028 * release documentation for your implementation to see if any other encodings are supported. Consult the release
    029 * documentation for your implementation to see if any other encodings are supported. </cite>
    030 * </p>
    031 *
    032 * <ul>
    033 * <li><code>US-ASCII</code><br>
    034 * Seven-bit ASCII, a.k.a. ISO646-US, a.k.a. the Basic Latin block of the Unicode character set.</li>
    035 * <li><code>ISO-8859-1</code><br>
    036 * ISO Latin Alphabet No. 1, a.k.a. ISO-LATIN-1.</li>
    037 * <li><code>UTF-8</code><br>
    038 * Eight-bit Unicode Transformation Format.</li>
    039 * <li><code>UTF-16BE</code><br>
    040 * Sixteen-bit Unicode Transformation Format, big-endian byte order.</li>
    041 * <li><code>UTF-16LE</code><br>
    042 * Sixteen-bit Unicode Transformation Format, little-endian byte order.</li>
    043 * <li><code>UTF-16</code><br>
    044 * Sixteen-bit Unicode Transformation Format, byte order specified by a mandatory initial byte-order mark (either order
    045 * accepted on input, big-endian used on output.)</li>
    046 * </ul>
    047 *
    048 * This perhaps would best belong in the Commons Lang project. Even if a similar class is defined in Commons Lang, it is
    049 * not foreseen that Commons Codec would be made to depend on Commons Lang.
    050 *
    051 * <p>
    052 * This class is immutable and thread-safe.
    053 * </p>
    054 *
    055 * @see <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    056 * @since 1.7
    057 * @version $Id: CharEncoding.java 1173287 2011-09-20 18:16:19Z ggregory $
    058 */
    059public class Charsets {
    060
    061    //
    062    // This class should only contain Charset instances for required encodings. This guarantees that it will load
    063    // correctly and without delay on all Java platforms.
    064    //
    065
    066    /**
    067     * Returns the given Charset or the default Charset if the given Charset is null.
    068     *
    069     * @param charset
    070     *            A charset or null.
    071     * @return the given Charset or the default Charset if the given Charset is null
    072     */
    073    public static Charset toCharset(final Charset charset) {
    074        return charset == null ? Charset.defaultCharset() : charset;
    075    }
    076
    077    /**
    078     * Returns a Charset for the named charset. If the name is null, return the default Charset.
    079     *
    080     * @param charset
    081     *            The name of the requested charset, may be null.
    082     * @return a Charset for the named charset
    083     * @throws java.nio.charset.UnsupportedCharsetException
    084     *             If the named charset is unavailable
    085     */
    086    public static Charset toCharset(final String charset) {
    087        return charset == null ? Charset.defaultCharset() : Charset.forName(charset);
    088    }
    089
    090    /**
    091     * CharEncodingISO Latin Alphabet No. 1, a.k.a. ISO-LATIN-1.
    092     * <p>
    093     * Every implementation of the Java platform is required to support this character encoding.
    094     *
    095     * @see <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    096     * @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
    097     */
    098    @Deprecated
    099    public static final Charset ISO_8859_1 = Charset.forName(CharEncoding.ISO_8859_1);
    100
    101    /**
    102     * Seven-bit ASCII, also known as ISO646-US, also known as the Basic Latin block of the Unicode character set.
    103     * <p>
    104     * Every implementation of the Java platform is required to support this character encoding.
    105     *
    106     * @see <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    107     * @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
    108     */
    109    @Deprecated
    110    public static final Charset US_ASCII = Charset.forName(CharEncoding.US_ASCII);
    111
    112    /**
    113     * Sixteen-bit Unicode Transformation Format, The byte order specified by a mandatory initial byte-order mark
    114     * (either order accepted on input, big-endian used on output)
    115     * <p>
    116     * Every implementation of the Java platform is required to support this character encoding.
    117     *
    118     * @see <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    119     * @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
    120     */
    121    @Deprecated
    122    public static final Charset UTF_16 = Charset.forName(CharEncoding.UTF_16);
    123
    124    /**
    125     * Sixteen-bit Unicode Transformation Format, big-endian byte order.
    126     * <p>
    127     * Every implementation of the Java platform is required to support this character encoding.
    128     *
    129     * @see <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    130     * @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
    131     */
    132    @Deprecated
    133    public static final Charset UTF_16BE = Charset.forName(CharEncoding.UTF_16BE);
    134
    135    /**
    136     * Sixteen-bit Unicode Transformation Format, little-endian byte order.
    137     * <p>
    138     * Every implementation of the Java platform is required to support this character encoding.
    139     *
    140     * @see <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    141     * @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
    142     */
    143    @Deprecated
    144    public static final Charset UTF_16LE = Charset.forName(CharEncoding.UTF_16LE);
    145
    146    /**
    147     * Eight-bit Unicode Transformation Format.
    148     * <p>
    149     * Every implementation of the Java platform is required to support this character encoding.
    150     *
    151     * @see <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    152     * @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
    153     */
    154    @Deprecated
    155    public static final Charset UTF_8 = Charset.forName(CharEncoding.UTF_8);
    156}