I18NUtil.java

// Copyright 2007 Google Inc.
//
// 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 com.google.enterprise.connector.common;

import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class I18NUtil {

  private I18NUtil() {
    // prevents instantiation
  }

  private static final Pattern LOCALE_PATTERN =
  Pattern.compile("(^[^_-]*)(?:[_-]([^_-]*)(?:[_-]([^_-]*))?)?");

/**
 * Convert a locale string from the RFC 3066 standard format
 * (used by GWS) to the Java locale format. You can call this on
 * any locale string obtained from an external source
 * (cookie, URL parameter, header, etc.). This method accepts
 * more than just the standard format and will also tolerate
 * capitalization discrepancies and the use of an underscore
 * in place of a hyphen.
 *
 * If an null or empty string is passed in, the platform default
 * locale is returned.
 */
  public static Locale getLocaleFromStandardLocaleString(String s) {
  if (s == null || s.length() == 0) {
    return Locale.getDefault();
  }

  Matcher matcher = LOCALE_PATTERN.matcher(s);

  // LOCALE_PATTERN will match any string, though it may not match the whole
  // string.  Specifically, it will not match a third _ or - or any
  // subsequent text.
  matcher.find();

  String language = makeSafe(matcher.group(1));
  String country = makeSafe(matcher.group(2));
  String variant = makeSafe(matcher.group(3));

  return new Locale(language, country, variant);
  }

 /**
  * Helper function for making null strings safe for comparisons, etc.
  *
  * @return (s == null) ? "" : s;
  */
  private static String makeSafe(String s) {
    return (s == null) ? "" : s;
  }

}