    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     * </p>
    095     * <p>
    096     * On Java 7 or later, use {@link java.nio.charset.StandardCharsets#ISO_8859_1} instead.
    097     * </p>
    098     *
    099     * @see <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    100     */
    101    public static final Charset ISO_8859_1 = Charset.forName(CharEncoding.ISO_8859_1);
    102
    103    /**
    104     * Seven-bit ASCII, also known as ISO646-US, also known as the Basic Latin block of the Unicode character set.
    105     * <p>
    106     * Every implementation of the Java platform is required to support this character encoding.
    107     * </p>
    108     * <p>
    109     * On Java 7 or later, use {@link java.nio.charset.StandardCharsets#ISO_8859_1} instead.
    110     * </p>
    111     *
    112     * @see <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    113     */
    114    public static final Charset US_ASCII = Charset.forName(CharEncoding.US_ASCII);
    115
    116    /**
    117     * Sixteen-bit Unicode Transformation Format, The byte order specified by a mandatory initial byte-order mark
    118     * (either order accepted on input, big-endian used on output)
    119     * <p>
    120     * Every implementation of the Java platform is required to support this character encoding.
    121     * </p>
    122     * <p>
    123     * On Java 7 or later, use {@link java.nio.charset.StandardCharsets#ISO_8859_1} instead.
    124     * </p>
    125     *
    126     * @see <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    127     */
    128    public static final Charset UTF_16 = Charset.forName(CharEncoding.UTF_16);
    129
    130    /**
    131     * Sixteen-bit Unicode Transformation Format, big-endian byte order.
    132     * <p>
    133     * Every implementation of the Java platform is required to support this character encoding.
    134     * </p>
    135     * <p>
    136     * On Java 7 or later, use {@link java.nio.charset.StandardCharsets#ISO_8859_1} instead.
    137     * </p>
    138     *
    139     * @see <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    140     */
    141    public static final Charset UTF_16BE = Charset.forName(CharEncoding.UTF_16BE);
    142
    143    /**
    144     * Sixteen-bit Unicode Transformation Format, little-endian byte order.
    145     * <p>
    146     * Every implementation of the Java platform is required to support this character encoding.
    147     * </p>
    148     * <p>
    149     * On Java 7 or later, use {@link java.nio.charset.StandardCharsets#ISO_8859_1} instead.
    150     * </p>
    151     *
    152     * @see <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    153     */
    154    public static final Charset UTF_16LE = Charset.forName(CharEncoding.UTF_16LE);
    155
    156    /**
    157     * Eight-bit Unicode Transformation Format.
    158     * <p>
    159     * Every implementation of the Java platform is required to support this character encoding.
    160     * </p>
    161     * <p>
    162     * On Java 7 or later, use {@link java.nio.charset.StandardCharsets#ISO_8859_1} instead.
    163     * </p>
    164     *
    165     * @see <a href="http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
    166     */
    167    public static final Charset UTF_8 = Charset.forName(CharEncoding.UTF_8);
    168}