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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.io;
import java.nio.charset.Charset;
import java.util.Collections;
import java.util.SortedMap;
import java.util.TreeMap;
/**
* Charsets required of every implementation of the Java platform.
*
* From the Java documentation
* Standard charsets:
*
* Every implementation of the Java platform is required to support the following character encodings. Consult
* the release documentation for your implementation to see if any other encodings are supported. Consult the release
* documentation for your implementation to see if any other encodings are supported.
*
*
*
* US-ASCII
* Seven-bit ASCII, a.k.a. ISO646-US, a.k.a. the Basic Latin block of the Unicode character set.ISO-8859-1
* ISO Latin Alphabet No. 1, a.k.a. ISO-LATIN-1.UTF-8
* Eight-bit Unicode Transformation Format.UTF-16BE
* Sixteen-bit Unicode Transformation Format, big-endian byte order.UTF-16LE
* Sixteen-bit Unicode Transformation Format, little-endian byte order.UTF-16
* Sixteen-bit Unicode Transformation Format, byte order specified by a mandatory initial byte-order mark (either order
* accepted on input, big-endian used on output.)
*
* @see Standard charsets
* @since 2.3
* @version $Id: Charsets.java 1686747 2015-06-21 18:44:49Z krosenvold $
*/
public class Charsets {
//
// This class should only contain Charset instances for required encodings. This guarantees that it will load
// correctly and without delay on all Java platforms.
//
/**
* Constructs a sorted map from canonical charset names to charset objects required of every implementation of the
* Java platform.
*
* From the Java documentation
* Standard charsets:
*
*
* @return An immutable, case-insensitive map from canonical charset names to charset objects.
* @see Charset#availableCharsets()
* @since 2.5
*/
public static SortedMap requiredCharsets() {
// maybe cache?
// TODO Re-implement on Java 7 to use java.nio.charset.StandardCharsets
final TreeMap m = new TreeMap(String.CASE_INSENSITIVE_ORDER);
m.put(ISO_8859_1.name(), ISO_8859_1);
m.put(US_ASCII.name(), US_ASCII);
m.put(UTF_16.name(), UTF_16);
m.put(UTF_16BE.name(), UTF_16BE);
m.put(UTF_16LE.name(), UTF_16LE);
m.put(UTF_8.name(), UTF_8);
return Collections.unmodifiableSortedMap(m);
}
/**
* Returns the given Charset or the default Charset if the given Charset is null.
*
* @param charset
* A charset or null.
* @return the given Charset or the default Charset if the given Charset is null
*/
public static Charset toCharset(final Charset charset) {
return charset == null ? Charset.defaultCharset() : charset;
}
/**
* Returns a Charset for the named charset. If the name is null, return the default Charset.
*
* @param charset
* The name of the requested charset, may be null.
* @return a Charset for the named charset
* @throws java.nio.charset.UnsupportedCharsetException
* If the named charset is unavailable
*/
public static Charset toCharset(final String charset) {
return charset == null ? Charset.defaultCharset() : Charset.forName(charset);
}
/**
* CharEncodingISO Latin Alphabet No. 1, a.k.a. ISO-LATIN-1.
*
* Every implementation of the Java platform is required to support this character encoding.
*
*
* @see Standard charsets
* @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
*/
@Deprecated
public static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
/**
*
* Seven-bit ASCII, also known as ISO646-US, also known as the Basic Latin block of the Unicode character set.
*
*
* Every implementation of the Java platform is required to support this character encoding.
*
*
* @see Standard charsets
* @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
*/
@Deprecated
public static final Charset US_ASCII = Charset.forName("US-ASCII");
/**
*
* Sixteen-bit Unicode Transformation Format, The byte order specified by a mandatory initial byte-order mark
* (either order accepted on input, big-endian used on output)
*
*
* Every implementation of the Java platform is required to support this character encoding.
*
*
* @see Standard charsets
* @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
*/
@Deprecated
public static final Charset UTF_16 = Charset.forName("UTF-16");
/**
*
* Sixteen-bit Unicode Transformation Format, big-endian byte order.
*
*
* Every implementation of the Java platform is required to support this character encoding.
*
*
* @see Standard charsets
* @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
*/
@Deprecated
public static final Charset UTF_16BE = Charset.forName("UTF-16BE");
/**
*
* Sixteen-bit Unicode Transformation Format, little-endian byte order.
*
*
* Every implementation of the Java platform is required to support this character encoding.
*
*
* @see Standard charsets
* @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
*/
@Deprecated
public static final Charset UTF_16LE = Charset.forName("UTF-16LE");
/**
*
* Eight-bit Unicode Transformation Format.
*
*
* Every implementation of the Java platform is required to support this character encoding.
*
*
* @see Standard charsets
* @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
*/
@Deprecated
public static final Charset UTF_8 = Charset.forName("UTF-8");
}