content: /**
   * 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
   * <p>
   * http://www.apache.org/licenses/LICENSE-2.0
   * <p>
   * 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.atlas.web.util;
  
  import java.text.DateFormat;
  import java.text.SimpleDateFormat;
  import java.util.Date;
  import java.util.TimeZone;
  import java.util.regex.Pattern;
  
  /**
   * Support function to parse and format date.
   */
  public final class DateTimeHelper {
      public static final  String  ISO8601_FORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";
      private static final String  DATE_PATTERN   = "(2\\d\\d\\d|19\\d\\d)-(0[1-9]|1[012])-(0[1-9]|1[0-9]|2[0-9]|3[01])T" + "([0-1][0-9]|2[0-3]):([0-5][0-9])Z";
      private static final Pattern PATTERN        = Pattern.compile(DATE_PATTERN);
  
      private static final ThreadLocal<DateFormat> DATE_FORMAT = ThreadLocal.withInitial(() -> {
          DateFormat dateFormat = new SimpleDateFormat(ISO8601_FORMAT);
  
          dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
  
          return dateFormat;
      });
  
      private DateTimeHelper() {
      }
  
      public static DateFormat getDateFormat() {
          return DATE_FORMAT.get();
      }
  
      public static String formatDateUTC(Date date) {
          return (date != null) ? getDateFormat().format(date) : null;
      }
  }
  