org.apache.tomcat.util.Charsets Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of grizzly-framework-http Show documentation
The newest version!
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2011 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */

package org.apache.tomcat.util;

import java.nio.charset.Charset;
import java.util.concurrent.ConcurrentHashMap;

/**
 * Charset utility class.
 *
 * @author Alexey Stashok
 */
public final class Charsets {
    public static final String DEFAULT_CHARACTER_ENCODING = "ISO-8859-1";

    private static final ConcurrentHashMap charsetAliasMap =
            new ConcurrentHashMap();

    public static final Charset ASCII_CHARSET = lookupCharset("ASCII");
    public static final Charset UTF8_CHARSET = lookupCharset("UTF-8");
    public static final Charset DEFAULT_CHARSET = lookupCharset(DEFAULT_CHARACTER_ENCODING);

    /**
     * Lookup a {@link Charset} by name.
     * Fixes Charset concurrency issue (http://paul.vox.com/library/post/the-mysteries-of-java-character-set-performance.html)
     *
     * @param charsetName
     * @return {@link Charset}
     */
    public static Charset lookupCharset(final String charsetName) {
        Charset charset = charsetAliasMap.get(charsetName);
        if (charset == null) {
            final Charset newCharset = Charset.forName(charsetName);
            final Charset prevCharset = charsetAliasMap.putIfAbsent(charsetName, newCharset);
            
            charset = prevCharset == null ? newCharset : prevCharset;
        }

        return charset;
    }
}