Charsets.java
/*
* 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.nio.charset.StandardCharsets;
import java.nio.charset.UnsupportedCharsetException;
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 <a href="https://docs.oracle.com/javase/8/docs/api/java/nio/charset/Charset.html">
* Standard charsets</a>:
* <p>
* <cite>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. </cite>
* </p>
*
* <ul>
* <li>{@code US-ASCII}<br>
* Seven-bit ASCII, a.k.a. ISO646-US, a.k.a. the Basic Latin block of the Unicode character set.</li>
* <li>{@code ISO-8859-1}<br>
* ISO Latin Alphabet No. 1, a.k.a. ISO-LATIN-1.</li>
* <li>{@code UTF-8}<br>
* Eight-bit Unicode Transformation Format.</li>
* <li>{@code UTF-16BE}<br>
* Sixteen-bit Unicode Transformation Format, big-endian byte order.</li>
* <li>{@code UTF-16LE}<br>
* Sixteen-bit Unicode Transformation Format, little-endian byte order.</li>
* <li>{@code UTF-16}<br>
* 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.)</li>
* </ul>
*
* @see <a href="https://docs.oracle.com/javase/8/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
* @since 2.3
*/
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.
//
private static final SortedMap<String, Charset> STANDARD_CHARSET_MAP;
static {
final SortedMap<String, Charset> standardCharsetMap = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
standardCharsetMap.put(StandardCharsets.ISO_8859_1.name(), StandardCharsets.ISO_8859_1);
standardCharsetMap.put(StandardCharsets.US_ASCII.name(), StandardCharsets.US_ASCII);
standardCharsetMap.put(StandardCharsets.UTF_16.name(), StandardCharsets.UTF_16);
standardCharsetMap.put(StandardCharsets.UTF_16BE.name(), StandardCharsets.UTF_16BE);
standardCharsetMap.put(StandardCharsets.UTF_16LE.name(), StandardCharsets.UTF_16LE);
standardCharsetMap.put(StandardCharsets.UTF_8.name(), StandardCharsets.UTF_8);
STANDARD_CHARSET_MAP = Collections.unmodifiableSortedMap(standardCharsetMap);
}
/**
* CharEncodingISO Latin Alphabet No. 1, a.k.a. ISO-LATIN-1.
* <p>
* Every implementation of the Java platform is required to support this character encoding.
* </p>
*
* @see <a href="https://docs.oracle.com/javase/8/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
* @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
*/
@Deprecated
public static final Charset ISO_8859_1 = StandardCharsets.ISO_8859_1;
/**
* <p>
* Seven-bit ASCII, also known as ISO646-US, also known as the Basic Latin block of the Unicode character set.
* </p>
* <p>
* Every implementation of the Java platform is required to support this character encoding.
* </p>
*
* @see <a href="https://docs.oracle.com/javase/8/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
* @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
*/
@Deprecated
public static final Charset US_ASCII = StandardCharsets.US_ASCII;
/**
* <p>
* 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)
* </p>
* <p>
* Every implementation of the Java platform is required to support this character encoding.
* </p>
*
* @see <a href="https://docs.oracle.com/javase/8/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
* @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
*/
@Deprecated
public static final Charset UTF_16 = StandardCharsets.UTF_16;
/**
* <p>
* Sixteen-bit Unicode Transformation Format, big-endian byte order.
* </p>
* <p>
* Every implementation of the Java platform is required to support this character encoding.
* </p>
*
* @see <a href="https://docs.oracle.com/javase/8/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
* @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
*/
@Deprecated
public static final Charset UTF_16BE = StandardCharsets.UTF_16BE;
/**
* <p>
* Sixteen-bit Unicode Transformation Format, little-endian byte order.
* </p>
* <p>
* Every implementation of the Java platform is required to support this character encoding.
* </p>
*
* @see <a href="https://docs.oracle.com/javase/8/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
* @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
*/
@Deprecated
public static final Charset UTF_16LE = StandardCharsets.UTF_16LE;
/**
* <p>
* Eight-bit Unicode Transformation Format.
* </p>
* <p>
* Every implementation of the Java platform is required to support this character encoding.
* </p>
*
* @see <a href="https://docs.oracle.com/javase/8/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
* @deprecated Use Java 7's {@link java.nio.charset.StandardCharsets}
*/
@Deprecated
public static final Charset UTF_8 = StandardCharsets.UTF_8;
/**
* Constructs a sorted map from canonical charset names to charset objects required of every implementation of the
* Java platform.
* <p>
* From the Java documentation <a href="https://docs.oracle.com/javase/8/docs/api/java/nio/charset/Charset.html">
* Standard charsets</a>:
* </p>
*
* @return An immutable, case-insensitive map from canonical charset names to charset objects.
* @see Charset#availableCharsets()
* @since 2.5
*/
public static SortedMap<String, Charset> requiredCharsets() {
return STANDARD_CHARSET_MAP;
}
/**
* 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 the given charset if non-null, otherwise return defaultCharset.
*
* @param charset The charset to test, may be null.
* @param defaultCharset The charset to return if charset is null, may be null.
* @return a Charset .
* @since 2.12.0
*/
public static Charset toCharset(final Charset charset, final Charset defaultCharset) {
return charset == null ? defaultCharset : charset;
}
/**
* Returns a Charset for the named charset. If the name is null, return the default Charset.
*
* @param charsetName The name of the requested charset, may be null.
* @return a Charset for the named charset.
* @throws UnsupportedCharsetException If the named charset is unavailable (unchecked exception).
*/
public static Charset toCharset(final String charsetName) throws UnsupportedCharsetException {
return toCharset(charsetName, Charset.defaultCharset());
}
/**
* Returns a Charset for the named charset. If the name is null, return the given default Charset.
*
* @param charsetName The name of the requested charset, may be null.
* @param defaultCharset The name charset to return if charsetName is null, may be null.
* @return a Charset for the named charset.
* @throws UnsupportedCharsetException If the named charset is unavailable (unchecked exception).
* @since 2.12.0
*/
public static Charset toCharset(final String charsetName, final Charset defaultCharset) throws UnsupportedCharsetException {
return charsetName == null ? defaultCharset : Charset.forName(charsetName);
}
}