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如何解析和转换DateTime为RFC 3339日期时间格式？

.netdatetimerfc3339atom-feed
56

如何将DateTime结构转换为其相应的RFC 3339格式的字符串表示形式，并/或解析此字符串表示形式回到DateTime结构？ RFC-3339日期时间格式在许多规范中使用，例如Atom Syndication Format。

8个回答
64
6
补充一点，这个库可以很好地解析和转换来自Google日历事件的日期为.NET DateTime格式，并且也可以将.NET DateTime格式转换为Google日历事件的日期。 - Yiannis Mpourkelis
22

这是一个使用C#实现的DateTime解析和转换为RFC-3339格式的示例。唯一的限制是DateTime必须是协调世界时（UTC）。

using System;
using System.Globalization;

namespace DateTimeConsoleApplication
{
    /// <summary>
    /// Provides methods for converting <see cref="DateTime"/> structures to and from the equivalent RFC 3339 string representation.
    /// </summary>
    public static class Rfc3339DateTime
    {
        //============================================================
        //  Private members
        //============================================================
        #region Private Members
        /// <summary>
        /// Private member to hold array of formats that RFC 3339 date-time representations conform to.
        /// </summary>
        private static string[] formats = new string[0];
        /// <summary>
        /// Private member to hold the DateTime format string for representing a DateTime in the RFC 3339 format.
        /// </summary>
        private const string format = "yyyy-MM-dd'T'HH:mm:ss.fffK";
        #endregion

        //============================================================
        //  Public Properties
        //============================================================
        #region Rfc3339DateTimeFormat
        /// <summary>
        /// Gets the custom format specifier that may be used to represent a <see cref="DateTime"/> in the RFC 3339 format.
        /// </summary>
        /// <value>A <i>DateTime format string</i> that may be used to represent a <see cref="DateTime"/> in the RFC 3339 format.</value>
        /// <remarks>
        /// <para>
        /// This method returns a string representation of a <see cref="DateTime"/> that 
        /// is precise to the three most significant digits of the seconds fraction; that is, it represents 
        /// the milliseconds in a date and time value. The <see cref="Rfc3339DateTimeFormat"/> is a valid 
        /// date-time format string for use in the <see cref="DateTime.ToString(String, IFormatProvider)"/> method.
        /// </para>
        /// </remarks>
        public static string Rfc3339DateTimeFormat
        {
            get
            {
                return format;
            }
        }
        #endregion

        #region Rfc3339DateTimePatterns
        /// <summary>
        /// Gets an array of the expected formats for RFC 3339 date-time string representations.
        /// </summary>
        /// <value>
        /// An array of the expected formats for RFC 3339 date-time string representations 
        /// that may used in the <see cref="DateTime.TryParseExact(String, string[], IFormatProvider, DateTimeStyles, out DateTime)"/> method.
        /// </value>
        public static string[] Rfc3339DateTimePatterns
        {
            get
            {
                if (formats.Length > 0)
                {
                    return formats;
                }
                else
                {
                    formats = new string[11];

                    // Rfc3339DateTimePatterns
                    formats[0] = "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffffffK";
                    formats[1] = "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'ffffffK";
                    formats[2] = "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffffK";
                    formats[3] = "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'ffffK";
                    formats[4] = "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffK";
                    formats[5] = "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'ffK";
                    formats[6] = "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fK";
                    formats[7] = "yyyy'-'MM'-'dd'T'HH':'mm':'ssK";

                    // Fall back patterns
                    formats[8] = "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffffffK"; // RoundtripDateTimePattern
                    formats[9] = DateTimeFormatInfo.InvariantInfo.UniversalSortableDateTimePattern;
                    formats[10] = DateTimeFormatInfo.InvariantInfo.SortableDateTimePattern;

                    return formats;
                }
            }
        }
        #endregion

        //============================================================
        //  Public Methods
        //============================================================
        #region Parse(string s)
        /// <summary>
        /// Converts the specified string representation of a date and time to its <see cref="DateTime"/> equivalent.
        /// </summary>
        /// <param name="s">A string containing a date and time to convert.</param>
        /// <returns>A <see cref="DateTime"/> equivalent to the date and time contained in <paramref name="s"/>.</returns>
        /// <remarks>
        /// The string <paramref name="s"/> is parsed using formatting information in the <see cref="DateTimeFormatInfo.InvariantInfo"/> object.
        /// </remarks>
        /// <exception cref="ArgumentNullException"><paramref name="s"/> is a <b>null</b> reference (Nothing in Visual Basic).</exception>
        /// <exception cref="FormatException"><paramref name="s"/> does not contain a valid RFC 3339 string representation of a date and time.</exception>
        public static DateTime Parse(string s)
        {
            //------------------------------------------------------------
            //  Validate parameter
            //------------------------------------------------------------
            if(s == null)
            {
                throw new ArgumentNullException("s");
            }

            DateTime result;
            if (Rfc3339DateTime.TryParse(s, out result))
            {
                return result;
            }
            else
            {
                throw new FormatException(String.Format(null, "{0} is not a valid RFC 3339 string representation of a date and time.", s));
            }
        }
        #endregion

        #region ToString(DateTime utcDateTime)
        /// <summary>
        /// Converts the value of the specified <see cref="DateTime"/> object to its equivalent string representation.
        /// </summary>
        /// <param name="utcDateTime">The Coordinated Universal Time (UTC) <see cref="DateTime"/> to convert.</param>
        /// <returns>A RFC 3339 string representation of the value of the <paramref name="utcDateTime"/>.</returns>
        /// <remarks>
        /// <para>
        /// This method returns a string representation of the <paramref name="utcDateTime"/> that 
        /// is precise to the three most significant digits of the seconds fraction; that is, it represents 
        /// the milliseconds in a date and time value.
        /// </para>
        /// <para>
        /// While it is possible to display higher precision fractions of a second component of a time value, 
        /// that value may not be meaningful. The precision of date and time values depends on the resolution 
        /// of the system clock. On Windows NT 3.5 and later, and Windows Vista operating systems, the clock's 
        /// resolution is approximately 10-15 milliseconds.
        /// </para>
        /// </remarks>
        /// <exception cref="ArgumentException">The specified <paramref name="utcDateTime"/> object does not represent a <see cref="DateTimeKind.Utc">Coordinated Universal Time (UTC)</see> value.</exception>
        public static string ToString(DateTime utcDateTime)
        {
            if (utcDateTime.Kind != DateTimeKind.Utc)
            {
                throw new ArgumentException("utcDateTime");
            }

            return utcDateTime.ToString(Rfc3339DateTime.Rfc3339DateTimeFormat, DateTimeFormatInfo.InvariantInfo);
        }
        #endregion

        #region TryParse(string s, out DateTime result)
        /// <summary>
        /// Converts the specified string representation of a date and time to its <see cref="DateTime"/> equivalent.
        /// </summary>
        /// <param name="s">A string containing a date and time to convert.</param>
        /// <param name="result">
        /// When this method returns, contains the <see cref="DateTime"/> value equivalent to the date and time 
        /// contained in <paramref name="s"/>, if the conversion succeeded, 
        /// or <see cref="DateTime.MinValue">MinValue</see> if the conversion failed. 
        /// The conversion fails if the s parameter is a <b>null</b> reference (Nothing in Visual Basic), 
        /// or does not contain a valid string representation of a date and time. 
        /// This parameter is passed uninitialized.
        /// </param>
        /// <returns><b>true</b> if the <paramref name="s"/> parameter was converted successfully; otherwise, <b>false</b>.</returns>
        /// <remarks>
        /// The string <paramref name="s"/> is parsed using formatting information in the <see cref="DateTimeFormatInfo.InvariantInfo"/> object.
        /// </remarks>
        public static bool TryParse(string s, out DateTime result)
        {
            //------------------------------------------------------------
            //  Attempt to convert string representation
            //------------------------------------------------------------
            bool wasConverted   = false;
            result              = DateTime.MinValue;

            if (!String.IsNullOrEmpty(s))
            {
                DateTime parseResult;
                if (DateTime.TryParseExact(s, Rfc3339DateTime.Rfc3339DateTimePatterns, DateTimeFormatInfo.InvariantInfo, DateTimeStyles.AdjustToUniversal, out parseResult))
                {
                    result          = DateTime.SpecifyKind(parseResult, DateTimeKind.Utc);
                    wasConverted    = true;
                }
            }

            return wasConverted;
        }
        #endregion
    }
}
6
为什么要为已经在 BCL 中的内容编写代码？ - Matt Howells
3
同意Matt的观点。RFC3339格式并不适用于DateTime.ToString标准格式之一，这很令人惊讶，但XmlConvert可以完成任务。例如，我使用XmlConvert.ToString(value, XmlDateTimeSerializationMode.Utc)。 - Bellarmine Head
嘿@AndrewWebb，如果数据格式如下2015-05-04T10:08:15+00:00，我该怎么办？我听说这也被认为是RFC3339，但是RFC3339不会将其识别为有效的DateTime，也没有任何XmlDateTimeSerializationMode。 - Stoyan Dimov
1
@StoyanDimov: 对我来说 var d = System.Xml.XmlConvert.ToDateTime("2015-05-04T10:08:15+00:00", System.Xml.XmlDateTimeSerializationMode.Utc); 是可行的。 - Bellarmine Head
4
谢谢您，如果您使用的是.NET Core，则无法使用XmlConvert。 - wonea
.NET Core 3.1（可能更早版本）具有XmlConvert。 - camios
2
这对我在.NET 6中有效：
public static class DateTimeExtensions
{
     public static string ToRFC3339(this DateTime date)
     {
         return date.ToUniversalTime().ToString("yyyy-MM-dd'T'HH:mm:ss.fffK");
     }
}
0

System.Text.Json 也可以实现这个功能：

JsonSerializer.Serialize(DateTime.Now)
-1
<input asp-for="StartDate" class="form-control" value="@DateTime.Now.ToString("yyyy-MM-ddThh:mm:ss")" />
1
请添加更多细节以扩展您的答案，例如工作代码或文档引用。 - Community
-1

为了完整起见，Newtonsoft.Json 也可以轻松实现：

JsonConvert.SerializeObject(DateTime.Now);

（与XmlConvert不同，它将在每个末尾转义双引号。）

-3
在.NET中（假设为UTC）：
 datetime.ToString("yyyy-MM-dd'T'HH:mm:ssZ")

DateTime.Parse() 可以用于将其转换回 DateTime 结构。

1
不要认为"YYYY-MM-DD'T'HH:mm:ss"是正确的；它没有与UTC的偏移量，也没有'Z'(=零偏移量)。 - Bellarmine Head
3
这对我不起作用。我必须使用datetime.ToUniversalTime().ToString("yyyy-MM-dd'T'HH:mm:ssZ")。 - Tomáš Linhart
4
只有当DateTime在协调世界时（国际标准时间）时才能正常工作。 - Mark Cidade
1
必须是yyyy和dd，不是大写字母。 - Aris
-6

一个简单的方程式可以得到你想要的结果：

rfcFormat = DateDiff("s", "1/1/1970", Now())
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