将 Xamarin 表单中的日期时间格式化为设备格式字符串 [英] Format DateTime in Xamarin Forms to Device Format string

问题描述

在运行 PCL Xamarin.Forms 项目时，如何将 DateTime 对象格式化为设备默认日期时间格式的字符串，我的部署目标包括 iOS、Android 和 Windows.

How can I format a DateTimeobject to a string in the device default datetime format when running a PCL Xamarin.Forms project and my deployement targets include iOS, Android and Windows.

DateTime.ToShortString() 根据此 thread 和这个 错误.

The DateTime.ToShortString() doesn't work as per MSDN requirement according to this thread and this bug.

是否有任何基于表单的解决方案，或者我是否需要从特定于平台的项目中获取它?

Is there any Forms based solution or do I need to get it from platform specific projects?

对于 Android，我可以使用 DI 从 Native 项目中执行以下操作:

For Android, I can do the following from Native project using DI:

String format = Settings.System.GetString(this.context.ContentResolver 
                                         , Settings.System.DateFormat);
string shortDateString = dateTime.ToString(format);

或者我也可以使用它(以下代码的 C# 版本):

OR I can use this too (the C# version of the below code):

DateFormat dateFormat = android.text.format.DateFormat.getDateFormat(context);

查看this SO 问题以了解要求更清楚(仅适用于 android，我希望它适用于所有平台，因为这是一个 Xamarin.Forms 问题).

Look into this SO question to understand the requirement more clearly (its only for android, I want it for all platforms as this is a Xamarin.Forms question).

由于 Xamarin Forms 中的 DatePicker 和 TimePicker 以设备格式显示日期和时间，我希望有办法在 PCL 中获取它.

Since the DatePicker and TimePicker in Xamarin Forms show the date and time in device format I am hoping there would a way to get it in the PCL.

PCL 中还有一个 Device 类，它包含平台、惯用语等信息.

Also there is a Device class in PCL which has information like platforms, idiom, etc.

推荐答案

由于我找不到任何 PCL 实现，我使用 DI 来实现需求.

As I could not find any PCL implementation I used DI to implement the requirement.

在 PCL 中的使用:

Usage in PCL :

DependencyService.Get<IDeviceInfoService>()?.ConvertToDeviceTimeFormat(DateTime.Now);    
DependencyService.Get<IDeviceInfoService>()?.ConvertToDeviceTimeFormat(DateTime.Now);

PCL:

public interface IDeviceInfoService
{
    string ConvertToDeviceShortDateFormat(DateTime inputDateTime);    
    string ConvertToDeviceTimeFormat(DateTime inputDateTime);
}

安卓:

[assembly: Dependency(typeof(DeviceInfoServiceImplementation))]
namespace Droid.Services
{
    public class DeviceInfoServiceImplementation : IDeviceInfoService
    {
        public string ConvertToDeviceShortDateFormat(DateTime inputDateTime)
        {
            var dateFormat = Android.Text.Format.DateFormat.GetDateFormat(Android.App.Application.Context);
            var epochDateTime = Helper.ConvertDateTimeToUnixTime(inputDateTime, true);

            if (epochDateTime == null)
            {
                return string.Empty;
            }

            using (var javaDate = new Java.Util.Date((long)epochDateTime))
            {
                return dateFormat.Format(javaDate);
            }
        }

        public string ConvertToDeviceTimeFormat(DateTime inputDateTime)
        {
            var timeFormat = Android.Text.Format.DateFormat.GetTimeFormat(Android.App.Application.Context);
            var epochDateTime = Helper.ConvertDateTimeToUnixTime(inputDateTime, true);

            if (epochDateTime == null)
            {
                return string.Empty;
            }

            using (var javaDate = new Java.Util.Date((long)epochDateTime))
            {
                return timeFormat.Format(javaDate);
            }
        }
    }
}

iOS:

[assembly: Dependency(typeof(DeviceInfoServiceImplementation))]
namespace iOS.Services
{
    public class DeviceInfoServiceImplementation : IDeviceInfoService
    {
        public string ConvertToDeviceShortDateFormat(DateTime inputDateTime)
        {
            var timeInEpoch = Helper.ConvertDateTimeToUnixTime(inputDateTime);

            if (timeInEpoch == null)
            {
                return string.Empty;
            }

            using (var dateInNsDate = NSDate.FromTimeIntervalSince1970((double)timeInEpoch))
            {
                using (var formatter = new NSDateFormatter
                {
                    TimeStyle = NSDateFormatterStyle.None,
                    DateStyle = NSDateFormatterStyle.Short,
                    Locale = NSLocale.CurrentLocale
                })
                {
                    return formatter.ToString(dateInNsDate);
                }
            }
        }

        public string ConvertToDeviceTimeFormat(DateTime inputDateTime)
        {
            var timeInEpoch = Helper.ConvertDateTimeToUnixTime(inputDateTime);

            if (timeInEpoch == null)
            {
                return string.Empty;
            }

            using (var dateInNsDate = NSDate.FromTimeIntervalSince1970((double)timeInEpoch))
            {
                using (var formatter = new NSDateFormatter
                {
                    TimeStyle = NSDateFormatterStyle.Short,
                    DateStyle = NSDateFormatterStyle.None,
                    Locale = NSLocale.CurrentLocale
                })
                {
                    return formatter.ToString(dateInNsDate);
                }
            }
        }
    }
}

视窗:

[assembly: Dependency(typeof(DeviceInfoServiceImplementation))]
namespace WinPhone.Services
{
    public class DeviceInfoServiceImplementation : IDeviceInfoService
    {
        public string ConvertToDeviceShortDateFormat(DateTime inputDateTime)
        {
            return inputDateTime.ToShortDateString();
        }

        public string ConvertToDeviceTimeFormat(DateTime inputDateTime)
        {
            return inputDateTime.ToShortTimeString();
        }
    }
}

辅助方法:

private static readonly DateTime EpochDateTime = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
public static long? ConvertDateTimeToUnixTime(DateTime? date, bool isDatarequiredInMilliSeconds = false, DateTimeKind dateTimeKind = DateTimeKind.Local) => date.HasValue == false
            ? (long?)null
            : Convert.ToInt64((DateTime.SpecifyKind(date.Value, dateTimeKind).ToUniversalTime() - EpochDateTime).TotalSeconds) * (isDatarequiredInMilliSeconds ? 1000 : 1);

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