这是一个方便的扩展方法,因为我猜测您正在尝试将一些描述文本映射到枚举值:
public static class EnumExtensions
{
public static string GetDescription(this Enum value)
{
var field = value.GetType().GetField(value.ToString());
if (field == null)
return value.ToString();
var attribute = field.GetCustomAttributes(typeof(DescriptionAttribute), false)
.OfType<DescriptionAttribute>()
.SingleOrDefault();
return attribute != null
? attribute.Description
: value.ToString();
}
}
像这样使用它:
public enum Foo
{
[Description("Hello")]
Bar,
[Description("World")]
Baz
}
var value = Foo.Bar;
var description = value.GetDescription(); // Hello
根据您的需要,如果反射对您来说太慢,您可以缓存描述,只需修改GetDescription
method.
EDIT:解释评论中的附加信息。
由于看起来您需要更具可扩展性的东西,您可以使用自定义属性:
[AttributeUsage(AttributeTargets.Field, AllowMultiple = true, Inherited = false)]
public sealed class DescriptionEntryAttribute : Attribute
{
public string Key { get; private set; }
public string Value { get; private set; }
public DescriptionEntryAttribute(string key, string value)
{
Key = key;
Value = value;
}
}
这会让你这样做:
public enum Foo
{
[DescriptionEntry("Name", "Hello")]
[DescriptionEntry("Title", "Some title")]
Bar,
[DescriptionEntry("Name", "World")]
[DescriptionEntry("Title", "Some title")]
Baz
}
现在,要阅读此内容,我建议您将其存储在这样的缓存中:
public static class EnumExtensions
{
private static readonly ConcurrentDictionary<Type, DescriptionCache> Caches = new ConcurrentDictionary<Type, DescriptionCache>();
public static string GetDescription(this Enum value, string key)
{
var enumType = value.GetType();
var cache = Caches.GetOrAdd(enumType, type => new DescriptionCache(type));
return cache.GetDescription(value, key);
}
public static IEnumerable<TEnum> GetValuesFromDescription<TEnum>(string key, string description)
where TEnum : struct
{
var cache = Caches.GetOrAdd(typeof(TEnum), type => new DescriptionCache(type));
return cache.GetValues(key, description).Select(value => (TEnum)(object)value);
}
private class DescriptionCache
{
private readonly ILookup<Enum, Tuple<string, string>> _items;
private readonly ILookup<Tuple<string, string>, Enum> _reverse;
public DescriptionCache(Type enumType)
{
if (!enumType.IsEnum)
throw new ArgumentException("Not an enum");
_items = (from value in Enum.GetValues(enumType).Cast<Enum>()
let field = enumType.GetField(value.ToString())
where field != null
from attribute in field.GetCustomAttributes(typeof (DescriptionEntryAttribute), false).OfType<DescriptionEntryAttribute>()
select new {value, key = attribute.Key, description = attribute.Value})
.ToLookup(i => i.value, i => Tuple.Create(i.key, i.description));
_reverse = (from grp in _items
from description in grp
select new {value = grp.Key, description})
.ToLookup(i => i.description, i => i.value);
}
public string GetDescription(Enum value, string key)
{
var tuple = _items[value].FirstOrDefault(i => i.Item1 == key);
return tuple != null ? tuple.Item2 : null;
}
public IEnumerable<Enum> GetValues(string key, string description)
{
return _reverse[Tuple.Create(key, description)];
}
}
}
这边走:
-
Foo.Bar.GetDescription("Name")
回报"Hello"
-
EnumExtensions.GetValuesFromDescription<Foo>("Title", "Some title")
返回一个序列,其中包含Foo.Bar
and Foo.Baz
这应该足以让您开始,现在您应该根据您的需要进行调整。例如,您可以使用枚举而不是字符串作为键,这将有助于避免键入错误,但我不知道这是否适合您的需求。