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Java SWT/JFace Utility Library including a Preferences Framework, Lightweight HTTP Server and macOS support.

There is a newer version: 20.1.0

/*
 * ====================================================================
 * 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * .
 *
 */

package io.github.albertus82.net.httpserver;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;

/**
 * Generates a date in the format required by the HTTP protocol.
 * 
 * Synchronization
 * 
 * 
 * This class is not synchronized. It is recommended to create separate
 * instances for each thread. If multiple threads access this class
 * concurrently, it must be synchronized externally.
 */
public class HttpDateGenerator {

	/** Date format pattern used to generate the header in RFC 1123 format. */
	public static final String PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";

	/** The time zone to use in the date header. */
	public static final TimeZone GMT = TimeZone.getTimeZone("GMT");

	private final DateFormat dateformat;
	private long dateAsLong = 0L;
	private String dateAsText = null;

	public HttpDateGenerator() {
		this.dateformat = new SimpleDateFormat(PATTERN_RFC1123, Locale.US);
		this.dateformat.setTimeZone(GMT);
	}

	public String getCurrentDate() {
		final long now = System.currentTimeMillis();
		if (now - this.dateAsLong > 1000) {
			// Generate new date string
			this.dateAsText = this.dateformat.format(new Date(now));
			this.dateAsLong = now;
		}
		return this.dateAsText;
	}

	public String format(final Date date) {
		return this.dateformat.format(date);
	}

}