c# - 如何通过 C# 类中的值获取变量名称

Question

目前我有一个类如下:

public static class JurisdictionList
{
    public const string NSW = "New South Wales";
    public const string NT = "Northern Territory";
    public const string QLD = "Queensland";
    public const string SA = "South Australia";
    public const string TAS = "Tasmania";
    public const string VIC = "Victoria";
    public const string WA = "Western Australia";
}

我想编写一个方法 string GetJurisdictionCode(string Jurisdiction) 来返回上述每个常量的名称及其值。例如 GetJurisdictionCode(JurisdictionList.QLD) 将返回 QLD。

目前我只知道使用 Switch Case 来做到这一点，但它看起来很长。有谁知道另一种解决方法？提前致谢。

Answer 1

好吧，你可以使用反射:

public static string GetJurisdictionCode(string jurisdiction)
{
    return typeof(JurisdictionList)
        .GetTypeInfo()
        .DeclaredFields
        .Where(f => (string) f.GetValue(null) == jurisdiction)
        .FirstOrDefault()
        ?.Name;
}

但我个人建议构建一个 Dictionary<string, string>从代码到名称，然后使用:

return codes.Where(kvp => kvp.Value == jurisdiction)
            .FirstOrDefault()
            ?.Name;

... 或建立第二个字典以朝另一个方向发展。如果你也想要命名常量，你总是可以通过反射建立两个字典，例如

public static class JurisdictionList
{
    public const string NSW = "New South Wales";
    public const string NT = "Northern Territory";
    public const string QLD = "Queensland";
    public const string SA = "South Australia";
    public const string TAS = "Tasmania";
    public const string VIC = "Victoria";
    public const string WA = "Western Australia";

    private static readonly Dictionary<string, string> CodeToName =
        typeof(JurisdictionList)
            .GetTypeInfo()
            .DeclaredFields
            .Where(f => f.FieldType == typeof(string))
            .ToDictionary(f => f.Name, f => f.GetValue(null));

    private static readonly Dictionary NameToCode =
        CodeToName.ToDictionary(kvp => kvp.Value, kvp => kvp.Key);

    // Methods using the dictionaries here
}

您还应该考虑使用枚举，然后从枚举到名称的映射。