CultureInfo.CurrentCulture与Thread.CurrentThread.CurrentCulture的区别探讨

问题背景 #

在开展多线程与日期解析测试时，需要修改当前线程的文化信息，由此产生疑问：CultureInfo.CurrentCulture 和 Thread.CurrentThread.CurrentCulture 之间是否存在差异？两者的智能提示完全一致：

获取或设置当前线程的区域性。
返回值：
表示当前线程区域性的对象。

测试代码 #

using System.Globalization;
using System.Threading;

Console.WriteLine("Hello, World!");
string dateValueString = "05/07/2022";

CultureInfo enGB = new CultureInfo("en-GB");
CultureInfo enUS = new CultureInfo("en-US");

DateTime result = DateTime.Now;
DateTime result2 = DateTime.Now;

Console.WriteLine($"CurrentCulture: {CultureInfo.CurrentCulture.Name} - ThreadCulture: {Thread.CurrentThread.CurrentCulture.Name}");
if (DateTime.TryParse(dateValueString, enGB, DateTimeStyles.None, out result))
{
    Console.WriteLine($"Original: {dateValueString} Parsed: {result}. Day: {result.Day}. Month: {result.Month}. Year: {result.Year}");
    result2 = DateTime.Parse(dateValueString);
    Console.WriteLine($"[Parse]Original: {dateValueString} Parsed: {result2}. Day: {result2.Day}. Month: {result2.Month}. Year: {result2.Year}");
}
Console.WriteLine(System.Environment.NewLine);

Thread.CurrentThread.CurrentCulture = enGB;
Console.WriteLine($"CurrentCulture: {CultureInfo.CurrentCulture.Name} - ThreadCulture: {Thread.CurrentThread.CurrentCulture.Name}");
if (DateTime.TryParse(dateValueString, enGB, DateTimeStyles.None, out result))
{
    Console.WriteLine($"Original: {dateValueString} Parsed: {result}. Day: {result.Day}. Month: {result.Month}. Year: {result.Year}");
    result2 = DateTime.Parse(dateValueString);
    Console.WriteLine($"[Parse]Original: {dateValueString} Parsed: {result2}. Day: {result2.Day}. Month: {result2.Month}. Year: {result2.Year}");
}
Console.WriteLine(System.Environment.NewLine);

Thread.CurrentThread.CurrentCulture = enUS;
Console.WriteLine($"CurrentCulture: {CultureInfo.CurrentCulture.Name} - ThreadCulture: {Thread.CurrentThread.CurrentCulture.Name}");
if (DateTime.TryParse(dateValueString, enGB, DateTimeStyles.None, out result))
{
    Console.WriteLine($"Original: {dateValueString} Parsed: {result}. Day: {result.Day}. Month: {result.Month}. Year: {result.Year}");
    result2 = DateTime.Parse(dateValueString);
    Console.WriteLine($"[Parse]Original: {dateValueString} Parsed: {result2}. Day: {result2.Day}. Month: {result2.Month}. Year: {result2.Year}");
}
Console.WriteLine(System.Environment.NewLine);

new Thread(() =>
{
    Thread.CurrentThread.CurrentCulture = enGB;
    Console.WriteLine($"CurrentCulture: {CultureInfo.CurrentCulture.Name} - ThreadCulture: {Thread.CurrentThread.CurrentCulture.Name}");
    if (DateTime.TryParse(dateValueString, enGB, DateTimeStyles.None, out result))
    {
        Console.WriteLine($"[Thread] Original: {dateValueString} Parsed: {result}. Day: {result.Day}. Month: {result.Month}. Year: {result.Year}");
        result2 = DateTime.Parse(dateValueString);
        Console.WriteLine($"[Thread][Parse]Original: {dateValueString} Parsed: {result2}. Day: {result2.Day}. Month: {result2.Month}. Year: {result2.Year}");

    }
}).Start();
Console.WriteLine(System.Environment.NewLine);

测试输出 #

CurrentCulture: es-ES - ThreadCulture: es-ES
Original: 05/07/2022 Parsed: 05/07/2022 0:00:00. Day: 5. Month: 7. Year: 2022
[Parse]Original: 05/07/2022 Parsed: 05/07/2022 0:00:00. Day: 5. Month: 7. Year: 2022


CurrentCulture: en-GB - ThreadCulture: en-GB
Original: 05/07/2022 Parsed: 05/07/2022 00:00:00. Day: 5. Month: 7. Year: 2022
[Parse]Original: 05/07/2022 Parsed: 05/07/2022 00:00:00. Day: 5. Month: 7. Year: 2022


CurrentCulture: en-US - ThreadCulture: en-US
Original: 05/07/2022 Parsed: 7/5/2022 12:00:00 AM. Day: 5. Month: 7. Year: 2022
[Parse]Original: 05/07/2022 Parsed: 5/7/2022 12:00:00 AM. Day: 7. Month: 5. Year: 2022



CurrentCulture: en-GB - ThreadCulture: en-GB
[Thread] Original: 05/07/2022 Parsed: 05/07/2022 00:00:00. Day: 5. Month: 7. Year: 2022
[Thread][Parse]Original: 05/07/2022 Parsed: 05/07/2022 00:00:00. Day: 5. Month: 7. Year: 2022

结论 #

CultureInfo.CurrentCulture 和 Thread.CurrentThread.CurrentCulture 完全等价，不存在功能差异。

在.NET底层实现中，CultureInfo.CurrentCulture 就是对 Thread.CurrentThread.CurrentCulture 的封装——读取时直接返回当前线程的文化信息，设置时也直接修改当前线程的文化属性。测试结果也验证了这一点：无论修改哪一个属性，另一个都会同步变化；在新线程中设置线程文化后，两个属性的值也完全一致。

日常开发中可根据代码可读性选择使用哪一个，效果完全相同。

内容的提问来源于stack exchange，提问作者blfuentes