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Tomcat example source code file (AcceptLanguage.java)

This example Tomcat source code file (AcceptLanguage.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

acceptlanguage, double, enumeration, enumeration, hashtable, hashtable, locale, numberformatexception, string, string, stringtokenizer, util, vector, vector

The Tomcat AcceptLanguage.java source code

/*
 *  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.tomcat.util.http;

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Locale;
import java.util.StringTokenizer;
import java.util.Vector;

/**
 * Util to process the "Accept-Language" header. Used by facade to implement
 * getLocale() and by StaticInterceptor.
 *
 * Not optimized - it's very slow.
 * 
 * @author James Duncan Davidson [duncan@eng.sun.com]
 * @author James Todd [gonzo@eng.sun.com]
 * @author Jason Hunter [jch@eng.sun.com]
 * @author Harish Prabandham
 * @author costin@eng.sun.com
 */
public class AcceptLanguage {

    public static Locale getLocale(String acceptLanguage) {
        if( acceptLanguage == null ) return Locale.getDefault();

        Hashtable<String,Vector languages =
            new Hashtable<String,Vector();
        Vector<Double> quality = new Vector();
        processAcceptLanguage(acceptLanguage, languages, quality);

        if (languages.size() == 0) return Locale.getDefault();

        Vector<Locale> l = new Vector();
        extractLocales( languages,quality, l);

        return (Locale)l.elementAt(0);
    }

    public static Enumeration getLocales(String acceptLanguage) {
            // Short circuit with an empty enumeration if null header
        if (acceptLanguage == null) {
            Vector<Locale> v = new Vector();
            v.addElement(Locale.getDefault());
            return v.elements();
        }
        
        Hashtable<String,Vector languages =
            new Hashtable<String,Vector();
        Vector<Double> quality=new Vector();
            processAcceptLanguage(acceptLanguage, languages , quality);

        if (languages.size() == 0) {
            Vector<Locale> v = new Vector();
            v.addElement(Locale.getDefault());
            return v.elements();
        }
            Vector<Locale> l = new Vector();
            extractLocales( languages, quality , l);
            return l.elements();
    }

    private static void processAcceptLanguage( String acceptLanguage,
            Hashtable<String,Vector languages, Vector q)
    {
        StringTokenizer languageTokenizer =
            new StringTokenizer(acceptLanguage, ",");

        while (languageTokenizer.hasMoreTokens()) {
            String language = languageTokenizer.nextToken().trim();
            int qValueIndex = language.indexOf(';');
            int qIndex = language.indexOf('q');
            int equalIndex = language.indexOf('=');
            Double qValue = new Double(1);

            if (qValueIndex > -1 &&
                    qValueIndex < qIndex &&
                    qIndex < equalIndex) {
                    String qValueStr = language.substring(qValueIndex + 1);
                language = language.substring(0, qValueIndex);
                qValueStr = qValueStr.trim().toLowerCase();
                qValueIndex = qValueStr.indexOf('=');
                qValue = new Double(0);
                if (qValueStr.startsWith("q") &&
                    qValueIndex > -1) {
                    qValueStr = qValueStr.substring(qValueIndex + 1);
                    try {
                        qValue = new Double(qValueStr.trim());
                    } catch (NumberFormatException nfe) {
                    }
                }
            }

            // XXX
            // may need to handle "*" at some point in time

            if (! language.equals("*")) {
                String key = qValue.toString();
                Vector<String> v;
                if (languages.containsKey(key)) {
                    v = languages.get(key) ;
                } else {
                    v= new Vector<String>();
                    q.addElement(qValue);
                }
                v.addElement(language);
                languages.put(key, v);
            }
        }
    }

    private static void extractLocales(Hashtable languages, Vector q,
            Vector<Locale> l)
    {
        // XXX We will need to order by q value Vector in the Future ?
        Enumeration e = q.elements();
        while (e.hasMoreElements()) {
            Vector v =
                (Vector)languages.get(((Double)e.nextElement()).toString());
            Enumeration le = v.elements();
            while (le.hasMoreElements()) {
                    String language = (String)le.nextElement();
                        String country = "";
                        int countryIndex = language.indexOf("-");
                if (countryIndex > -1) {
                    country = language.substring(countryIndex + 1).trim();
                    language = language.substring(0, countryIndex).trim();
                }
                l.addElement(new Locale(language, country));
            }
        }
    }


}

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