using System;
using System.Collections.Generic;
using System.Linq;

public static class RelativeDateHelper
{
    private static Dictionary<double, Func<double, string>> sm_Dict = null;

    private static Dictionary<double, Func<double, string>> DictionarySetup()
    {
        var dict = new Dictionary<double, Func<double, string>>();
        dict.Add(0.75, (mins) => "less than a minute");
        dict.Add(1.5, (mins) => "about a minute");
        dict.Add(45, (mins) => string.Format("{0} minutes", Math.Round(mins)));
        dict.Add(90, (mins) => "about an hour");
        dict.Add(1440, (mins) => string.Format("about {0} hours", Math.Round(Math.Abs(mins / 60)))); // 60 * 24
        dict.Add(2880, (mins) => "a day"); // 60 * 48
        dict.Add(43200, (mins) => string.Format("{0} days", Math.Floor(Math.Abs(mins / 1440)))); // 60 * 24 * 30
        dict.Add(86400, (mins) => "about a month"); // 60 * 24 * 60
        dict.Add(525600, (mins) => string.Format("{0} months", Math.Floor(Math.Abs(mins / 43200)))); // 60 * 24 * 365 
        dict.Add(1051200, (mins) => "about a year"); // 60 * 24 * 365 * 2
        dict.Add(double.MaxValue, (mins) => string.Format("{0} years", Math.Floor(Math.Abs(mins / 525600))));

        return dict;
    }

    public static string ToRelativeDate(this DateTime input)
    {
        TimeSpan oSpan = DateTime.Now.Subtract(input);
        double TotalMinutes = oSpan.TotalMinutes;
        string Suffix = " ago";

        if (TotalMinutes < 0.0)
        {
            TotalMinutes = Math.Abs(TotalMinutes);
            Suffix = " from now";
        }

        if (null == sm_Dict)
            sm_Dict = DictionarySetup();

        return sm_Dict.First(n => TotalMinutes < n.Key).Value.Invoke(TotalMinutes) + Suffix;
    }
}

与此问题的另一个答案相同，但作为静态字典的扩展方法。

public string getRelativeDateTime(DateTime date)
{
    TimeSpan ts = DateTime.Now - date;
    if (ts.TotalMinutes < 1)//seconds ago
        return "just now";
    if (ts.TotalHours < 1)//min ago
        return (int)ts.TotalMinutes == 1 ? "1 Minute ago" : (int)ts.TotalMinutes + " Minutes ago";
    if (ts.TotalDays < 1)//hours ago
        return (int)ts.TotalHours == 1 ? "1 Hour ago" : (int)ts.TotalHours + " Hours ago";
    if (ts.TotalDays < 7)//days ago
        return (int)ts.TotalDays == 1 ? "1 Day ago" : (int)ts.TotalDays + " Days ago";
    if (ts.TotalDays < 30.4368)//weeks ago
        return (int)(ts.TotalDays / 7) == 1 ? "1 Week ago" : (int)(ts.TotalDays / 7) + " Weeks ago";
    if (ts.TotalDays < 365.242)//months ago
        return (int)(ts.TotalDays / 30.4368) == 1 ? "1 Month ago" : (int)(ts.TotalDays / 30.4368) + " Months ago";
    //years ago
    return (int)(ts.TotalDays / 365.242) == 1 ? "1 Year ago" : (int)(ts.TotalDays / 365.242) + " Years ago";
}

一个月和一年中的天数的转换值取自谷歌。

iPhone Objective-C版本

+ (NSString *)timeAgoString:(NSDate *)date {
    int delta = -(int)[date timeIntervalSinceNow];

    if (delta < 60)
    {
        return delta == 1 ? @"one second ago" : [NSString stringWithFormat:@"%i seconds ago", delta];
    }
    if (delta < 120)
    {
        return @"a minute ago";
    }
    if (delta < 2700)
    {
        return [NSString stringWithFormat:@"%i minutes ago", delta/60];
    }
    if (delta < 5400)
    {
        return @"an hour ago";
    }
    if (delta < 24 * 3600)
    {
        return [NSString stringWithFormat:@"%i hours ago", delta/3600];
    }
    if (delta < 48 * 3600)
    {
        return @"yesterday";
    }
    if (delta < 30 * 24 * 3600)
    {
        return [NSString stringWithFormat:@"%i days ago", delta/(24*3600)];
    }
    if (delta < 12 * 30 * 24 * 3600)
    {
        int months = delta/(30*24*3600);
        return months <= 1 ? @"one month ago" : [NSString stringWithFormat:@"%i months ago", months];
    }
    else
    {
        int years = delta/(12*30*24*3600);
        return years <= 1 ? @"one year ago" : [NSString stringWithFormat:@"%i years ago", years];
    }
}

@杰夫

var ts=新时间跨度（DateTime.UtcNow.Ticks-dt.Ticks）；

对DateTime执行减法仍会返回TimeSpan。

所以你可以这样做

(DateTime.UtcNow - dt).TotalSeconds

我也很惊讶地看到常数用手相乘，然后注释加上乘法。这是错误的优化吗？

通过在客户端执行此逻辑，可以减少服务器端负载。在一些Digg页面上查看源代码以供参考。它们让服务器发出一个由Javascript处理的历元时间值。这样，您就不需要管理最终用户的时区。新的服务器端代码类似于：

public string GetRelativeTime(DateTime timeStamp)
{
    return string.Format("<script>printdate({0});</script>", timeStamp.ToFileTimeUtc());
}

您甚至可以在那里添加一个NOSCRIPT块，然后执行ToString（）。

用于客户端gwt的Java：

import java.util.Date;

public class RelativeDateFormat {

 private static final long ONE_MINUTE = 60000L;
 private static final long ONE_HOUR = 3600000L;
 private static final long ONE_DAY = 86400000L;
 private static final long ONE_WEEK = 604800000L;

 public static String format(Date date) {

  long delta = new Date().getTime() - date.getTime();
  if (delta < 1L * ONE_MINUTE) {
   return toSeconds(delta) == 1 ? "one second ago" : toSeconds(delta)
     + " seconds ago";
  }
  if (delta < 2L * ONE_MINUTE) {
   return "one minute ago";
  }
  if (delta < 45L * ONE_MINUTE) {
   return toMinutes(delta) + " minutes ago";
  }
  if (delta < 90L * ONE_MINUTE) {
   return "one hour ago";
  }
  if (delta < 24L * ONE_HOUR) {
   return toHours(delta) + " hours ago";
  }
  if (delta < 48L * ONE_HOUR) {
   return "yesterday";
  }
  if (delta < 30L * ONE_DAY) {
   return toDays(delta) + " days ago";
  }
  if (delta < 12L * 4L * ONE_WEEK) {
   long months = toMonths(delta);
   return months <= 1 ? "one month ago" : months + " months ago";
  } else {
   long years = toYears(delta);
   return years <= 1 ? "one year ago" : years + " years ago";
  }
 }

 private static long toSeconds(long date) {
  return date / 1000L;
 }

 private static long toMinutes(long date) {
  return toSeconds(date) / 60L;
 }

 private static long toHours(long date) {
  return toMinutes(date) / 60L;
 }

 private static long toDays(long date) {
  return toHours(date) / 24L;
 }

 private static long toMonths(long date) {
  return toDays(date) / 30L;
 }

 private static long toYears(long date) {
  return toMonths(date) / 365L;
 }

}