/*
* ====================================================================
* 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
* <http://www.apache.org/>.
*
*/
package org.apache.http.protocol;
import org.apache.http.annotation.
ThreadingBehavior;
import org.apache.http.annotation.
Contract;
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.
*
* @since 4.0
*/
@
Contract(threading =
ThreadingBehavior.
SAFE)
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() {
super();
this.
dateformat = new
SimpleDateFormat(
PATTERN_RFC1123,
Locale.
US);
this.
dateformat.
setTimeZone(
GMT);
}
public synchronized
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;
}
}