de.cosmocode.commons.converter.LocaleLanguageIsoConverter.java Source code

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Here is the source code for de.cosmocode.commons.converter.LocaleLanguageIsoConverter.java

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/**
 * Copyright 2010 - 2013 CosmoCode GmbH
 *
 * Licensed 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 de.cosmocode.commons.converter;

import com.google.common.base.Preconditions;
import de.cosmocode.commons.Codec;
import de.cosmocode.commons.Patterns;
import de.cosmocode.commons.TrimMode;
import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Locale;
import java.util.MissingResourceException;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/**
 * A {@link LanguageIsoConverter} that is backed by {@link Locale}.
 *
 * @since 1.8
 * @author Oliver Lorenz
 */
public class LocaleLanguageIsoConverter extends Codec<Locale, String> implements LanguageIsoConverter {

    private static final Logger LOG = LoggerFactory.getLogger(LocaleLanguageIsoConverter.class);

    private final ConcurrentMap<String, String> cache = new ConcurrentHashMap<String, String>();

    @Override
    public String toThreeLetter(String iso6391) {
        Preconditions.checkNotNull(iso6391, "iso6391 must not be null");
        if (Patterns.ISO_639_1.matcher(iso6391).matches()) {
            // ISO 639-1 to ISO 639-2 (two-letter to three-letter)
            try {
                return new Locale(iso6391).getISO3Language();
            } catch (MissingResourceException e) {
                throw new IsoConversionException("No known three-letter language code for " + iso6391, e);
            }
        } else if (Patterns.ISO_639_2.matcher(iso6391).matches()) {
            // already ISO 639-2 (three letter)
            return iso6391;
        } else if (StringUtils.isBlank(iso6391)) {
            // this is here for convenience, to allow empty languages
            return TrimMode.EMPTY.apply(iso6391);
        } else {
            throw new IllegalArgumentException("given language code must be either iso 639-1 or iso 639-2");
        }
    }

    @Override
    public String toTwoLetter(String iso6392) {
        // sanity check on arguments
        Preconditions.checkNotNull(iso6392, "iso6392 must not be null");
        if (Patterns.ISO_639_1.matcher(iso6392).matches()) {
            // already ISO 639-1 (two letter)
            return iso6392;
        } else if (StringUtils.isBlank(iso6392)) {
            // this is here for convenience, to allow empty languages
            return TrimMode.EMPTY.apply(iso6392);
        }
        Preconditions.checkArgument(Patterns.ISO_639_2.matcher(iso6392).matches(),
                "Language Code %s not in ISO 639-2", iso6392);

        // try to get two letter code from cache
        final String fromCache = cache.get(iso6392);
        if (fromCache != null) {
            return fromCache;
        }

        // search for three letter code in the known language codes of Locale
        for (final String iso6391 : Locale.getISOLanguages()) {
            final String threeLetter = new Locale(iso6391).getISO3Language();
            if (iso6392.equals(threeLetter)) {
                LOG.trace("Found ISO 639-1 language code: {} for ISO 639-2 language code: {}", iso6391, iso6392);
                cache.put(iso6392, iso6391);
                return iso6391;
            }
        }

        // if we arrive here then the Locale class could not find the iso3 code
        throw new IsoConversionException("No known ISO 639-1 language code for " + iso6392);
    }

    @Override
    public String encode(Locale input) {
        return toThreeLetter(input.getLanguage());
    }

    @Override
    public Locale decode(String input) {
        return new Locale(toTwoLetter(input));
    }

}