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28 package org.apache.hc.core5.http.protocol;
29
30 import java.text.DateFormat;
31 import java.text.SimpleDateFormat;
32 import java.util.Date;
33 import java.util.Locale;
34 import java.util.TimeZone;
35
36 import org.apache.hc.core5.annotation.Contract;
37 import org.apache.hc.core5.annotation.ThreadingBehavior;
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44 @Contract(threading = ThreadingBehavior.SAFE)
45 public class HttpDateGenerator {
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47 private static final int GRANULARITY_MILLIS = 1000;
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50 public static final String PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";
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52
53 public static final TimeZone GMT = TimeZone.getTimeZone("GMT");
54
55
56 public static final HttpDateGeneratorttpDateGenerator.html#HttpDateGenerator">HttpDateGenerator INSTANCE = new HttpDateGenerator(PATTERN_RFC1123, Locale.US, GMT);
57
58 private final DateFormat dateformat;
59 private long dateAsMillis = 0L;
60 private String dateAsText = null;
61
62 HttpDateGenerator() {
63 super();
64 this.dateformat = new SimpleDateFormat(PATTERN_RFC1123, Locale.US);
65 this.dateformat.setTimeZone(GMT);
66 }
67
68 private HttpDateGenerator(final String pattern, final Locale locale, final TimeZone timeZone) {
69 this.dateformat = new SimpleDateFormat(pattern, locale);
70 this.dateformat.setTimeZone(timeZone);
71 }
72
73 public synchronized String getCurrentDate() {
74 final long now = System.currentTimeMillis();
75 if (now - this.dateAsMillis > GRANULARITY_MILLIS) {
76
77 this.dateAsText = this.dateformat.format(new Date(now));
78 this.dateAsMillis = now;
79 }
80 return this.dateAsText;
81 }
82
83 }