我可以有一个枚举作为键值对吗？
public enum infringementCategory
{
Infringement,
OFN
}
如果我选择Infringement，我应该得到“INF0001”，如果我选择OFN，我应该得到“INF0002”
有可能吗？
【问题讨论】：
您可以使用装饰器将字符串表示与您的枚举值相关联。检查这个问题：Enum ToString with user friendly strings
它看起来像：
public enum infringementCategory
{
[Description("INF0001")]
Infringement,
[Description("INF0002")]
OFN
}
看起来比使用 Dictionary 更整洁，并且需要更少的维护。
【讨论】：
这些扩展怎么样：
public static class EnumExtension
{
/// <summary>
/// Gets the string of an DescriptionAttribute of an Enum.
/// </summary>
/// <param name="value">The Enum value for which the description is needed.</param>
/// <returns>If a DescriptionAttribute is set it return the content of it.
/// Otherwise just the raw name as string.</returns>
public static string Description(this Enum value)
{
if (value == null)
{
throw new ArgumentNullException("value");
}
string description = value.ToString();
FieldInfo fieldInfo = value.GetType().GetField(description);
DescriptionAttribute[] attributes =
(DescriptionAttribute[])
fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), false);
if (attributes != null && attributes.Length > 0)
{
description = attributes[0].Description;
}
return description;
}
/// <summary>
/// Creates an List with all keys and values of a given Enum class
/// </summary>
/// <typeparam name="T">Must be derived from class Enum!</typeparam>
/// <returns>A list of KeyValuePair<Enum, string> with all available
/// names and values of the given Enum.</returns>
public static IList<KeyValuePair<Enum, string>> ToList<T>() where T : struct
{
var type = typeof(T);
if (!type.IsEnum)
{
throw new ArgumentException("T must be an enum");
}
return (IList<KeyValuePair<Enum, string>>)
Enum.GetValues(type)
.OfType<Enum>()
.Select(e => new KeyValuePair<Enum, string>(e, e.Description()))
.ToArray();
}
public static T GetValueFromDescription<T>(string description) where T : struct
{
var type = typeof(T);
if(!type.IsEnum)
{
throw new ArgumentException("T must be an enum");
}
foreach(var field in type.GetFields())
{
var attribute = Attribute.GetCustomAttribute(field,
typeof(DescriptionAttribute)) as DescriptionAttribute;
if(attribute != null)
{
if(attribute.Description == description)
{
return (T)field.GetValue(null);
}
}
else
{
if(field.Name == description)
{
return (T)field.GetValue(null);
}
}
}
throw new ArgumentOutOfRangeException("description");
// or return default(T);
}
}
有了这个，你可以像这样构建你的枚举：
public enum Foo
{
[Description("Foo - Something")]
Something,
[Description("Foo - Anything")]
Anything,
}
然后像这样得到你的列表：
var list = EnumExtension.ToList<Foo>();
【讨论】：
您可以将标题 (INF0001)... 存储在 Dictionary<infringementCategory, string>
【讨论】：
见：
public enum InfringementCategory
{
[EnumNamedConstant(Description = "INF0001")]
Infringement,
[EnumNamedConstant(Description = "INF0002")]
OFN
}
public class Test{
public void Test()
{
String result = InfringementCategory.Infringement.GetDescription();
}
}
这里是扩展方法...
#region [ EnumNamedConstantAttribute ]
[AttributeUsage(AttributeTargets.Field, AllowMultiple = false)]
public class EnumNamedConstantAttribute : Attribute
{
public string Description { get; set; }
public string Value { get; set; }
}
#endregion
#region EnumUtilities
public static class EnumUtilities
{
#region [ + Extension Methods ]
#region [ GetDescription ]
public static string GetDescription(this Enum constant)
{
return EnumUtilities.GetEnumNamedConstantAttribute(constant).Description;
}
#endregion
#region [ GetStringValue ]
public static string GetStringValue(this Enum constant)
{
return GetEnumNamedConstantValue(constant);
}
#endregion
#endregion
#region [ + Static Methods ]
#region [ GetEnumerable ]
public static IEnumerable<EnumNamedConstantAttribute> GetEnumerable<T>()
{
T instancia = Activator.CreateInstance<T>();
FieldInfo[] objInfos = instancia.GetType().GetFields(BindingFlags.Public | BindingFlags.Static);
foreach (FieldInfo objFileInfo in objInfos)
{
Enum constant = (Enum)objFileInfo.GetValue(objFileInfo);
if (objFileInfo.GetCustomAttributes(typeof(EnumNamedConstantAttribute), false).Length != 0)
{
yield return new EnumNamedConstantAttribute()
{
Description = EnumUtilities.GetEnumNamedConstantAttribute(constant).Description,
Value = GetEnumNamedConstantValue(constant)
};
}
}
}
#endregion
#endregion
#region [ + Privates ]
#region [ GetEnumNamedConstantAttribute ]
private static EnumNamedConstantAttribute GetEnumNamedConstantAttribute(Enum constant)
{
FieldInfo[] objInfos = constant.GetType().GetFields(BindingFlags.Public | BindingFlags.Static);
foreach (FieldInfo objFileInfo in objInfos)
{
Enum constantItem = (Enum)objFileInfo.GetValue(objFileInfo);
if (constantItem.GetHashCode().Equals(constant.GetHashCode()))
{
object[] attributes = objFileInfo.GetCustomAttributes(typeof(EnumNamedConstantAttribute), false);
if (attributes.Length > 0)
return (EnumNamedConstantAttribute)attributes[0];
}
}
return null;
}
#endregion
#region [ GetEnumNamedConstantValue ]
private static string GetEnumNamedConstantValue(Enum constant)
{
string sValue = (constant.GetHashCode()).ToString();
EnumNamedConstantAttribute objRet = EnumUtilities.GetEnumNamedConstantAttribute(constant);
if (objRet != null)
{
String sAux = objRet.Value;
if (!String.IsNullOrEmpty(sAux))
sValue = objRet.Value;
}
return sValue;
}
#endregion
#endregion
}
#endregion
【讨论】：
更新：
感谢 Oliver 指出System.Component.DescriptionAttribute。操作方法如下：
public enum infringementCategory
{
[Description("INF0001")]
Infringement,
[Description("INF0002")]
OFN
}
public static class DescriptionExtensions
{
public static string GetDescriptionValue(this Enum value)
{
// Get the type
Type type = value.GetType();
// Get fieldinfo for this type
FieldInfo fieldInfo = type.GetField(value.ToString());
// Get the stringvalue attributes
DescriptionAttribute[] attribs = fieldInfo.GetCustomAttributes(
typeof(DescriptionAttribute), false) as DescriptionAttribute[];
// Return the first if there was a match.
return attribs.Length > 0 ? attribs[0].Description : null;
}
}
public class Program
{
static void Main(string[] args)
{
infringementCategory category = infringementCategory.OFN;
string description = category.GetDescriptionValue();
}
}
【讨论】：
DescriptionAttribute，为什么还要使用自写属性？
您有多种选择：
建议使用 vc74 的字典。这是有效的，并且可以将您的枚举与属性分离。
switch 语句
如果您只想与每个相关联的是一个整数，您可以使用：
public enum InfringementCategory
{
Infringement = 1,
OFN = 2
}
然后将(int)myEnum放入String.Format中，变成你想要的形式的字符串。
属性
public enum InfringementCategory
{
[InfID("INF0001")]Infringement,
[InfID("INF0002")]OFN
}
为了提高性能，您可以使用一次反射来填充字典。
【讨论】：