stack/core/src/main/java/org/apache/usergrid/utils/DateUtils.java

/*
 * 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.usergrid.utils;


import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.SimpleTimeZone;


/**
 * Utilities for parsing and formatting dates.
 * <p/>
 * Note that this class doesn't use static methods because of the synchronization issues with SimpleDateFormat. This
 * lets synchronization be done on a per-object level, instead of on a per-class level.
 */
public class DateUtils {

    /** ISO 8601 parser */
    protected final SimpleDateFormat iso8601DateParser = new SimpleDateFormat( "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'" );

    /** Alternate ISO 8601 parser without fractional seconds */
    protected final SimpleDateFormat alternateIo8601DateParser = new SimpleDateFormat( "yyyy-MM-dd'T'HH:mm:ss'Z'" );

    /** RFC 822 parser */
    protected final SimpleDateFormat rfc822DateParser =
            new SimpleDateFormat( "EEE, dd MMM yyyy HH:mm:ss z", Locale.US );


    /** Constructs a new DateUtils object, ready to parse/format dates. */
    public DateUtils() {
        iso8601DateParser.setTimeZone( new SimpleTimeZone( 0, "GMT" ) );
        rfc822DateParser.setTimeZone( new SimpleTimeZone( 0, "GMT" ) );
        alternateIo8601DateParser.setTimeZone( new SimpleTimeZone( 0, "GMT" ) );
    }


    public static DateUtils instance = new DateUtils();


    /**
     * Formats the specified date as an ISO 8601 string.
     *
     * @param date The date to format.
     *
     * @return The ISO 8601 string representing the specified date.
     */
    public String formatIso8601Date( Date date ) {
        synchronized ( iso8601DateParser ) {
            return iso8601DateParser.format( date );
        }
    }


    public String iso8601DateNow() {
        return formatIso8601Date( new Date() );
    }
}