我有以下列举:

public enum AuthenticationMethod
{
    FORMS = 1,
    WINDOWSAUTHENTICATION = 2,
    SINGLESIGNON = 3
}

然而问题是,当我请求AuthenticationMethod时,我需要“FORMS”这个词。表单而不是id

对于这个问题,我找到了以下解决方案(链接):

首先,我需要创建一个自定义属性“StringValue”:

public class StringValue : System.Attribute
{
    private readonly string _value;

    public StringValue(string value)
    {
        _value = value;
    }

    public string Value
    {
        get { return _value; }
    }

}

然后我可以将这个属性添加到我的枚举器中:

public enum AuthenticationMethod
{
    [StringValue("FORMS")]
    FORMS = 1,
    [StringValue("WINDOWS")]
    WINDOWSAUTHENTICATION = 2,
    [StringValue("SSO")]
    SINGLESIGNON = 3
}

当然,我需要一些东西来检索StringValue:

public static class StringEnum
{
    public static string GetStringValue(Enum value)
    {
        string output = null;
        Type type = value.GetType();

        //Check first in our cached results...

        //Look for our 'StringValueAttribute' 

        //in the field's custom attributes

        FieldInfo fi = type.GetField(value.ToString());
        StringValue[] attrs =
           fi.GetCustomAttributes(typeof(StringValue),
                                   false) as StringValue[];
        if (attrs.Length > 0)
        {
            output = attrs[0].Value;
        }

        return output;
    }
}

很好,现在我已经有了工具来获取枚举器的字符串值。 然后我可以这样使用它:

string valueOfAuthenticationMethod = StringEnum.GetStringValue(AuthenticationMethod.FORMS);

好的,现在所有这些工作就像一个魅力,但我发现它有很多工作。我想知道有没有更好的解决办法。

我还尝试了一些字典和静态属性,但这也不是更好。


当前回答

我真的很喜欢Jakub Šturc的答案,但它的缺点是不能与开关case语句一起使用。下面是他的回答的一个稍微修改的版本,可以与switch语句一起使用:

public sealed class AuthenticationMethod
{
    #region This code never needs to change.
    private readonly string _name;
    public readonly Values Value;

    private AuthenticationMethod(Values value, String name){
        this._name = name;
        this.Value = value;
    }

    public override String ToString(){
        return _name;
    }
    #endregion

    public enum Values
    {
        Forms = 1,
        Windows = 2,
        SSN = 3
    }

    public static readonly AuthenticationMethod FORMS = new AuthenticationMethod (Values.Forms, "FORMS");
    public static readonly AuthenticationMethod WINDOWSAUTHENTICATION = new AuthenticationMethod (Values.Windows, "WINDOWS");
    public static readonly AuthenticationMethod SINGLESIGNON = new AuthenticationMethod (Values.SSN, "SSN");
}

所以你得到了Jakub Šturc的答案的所有好处,另外我们可以像这样使用switch语句:

var authenticationMethodVariable = AuthenticationMethod.FORMS;  // Set the "enum" value we want to use.
var methodName = authenticationMethodVariable.ToString();       // Get the user-friendly "name" of the "enum" value.

// Perform logic based on which "enum" value was chosen.
switch (authenticationMethodVariable.Value)
{
    case authenticationMethodVariable.Values.Forms: // Do something
        break;
    case authenticationMethodVariable.Values.Windows: // Do something
        break;
    case authenticationMethodVariable.Values.SSN: // Do something
        break;      
}

其他回答

在你的问题中,你从未说过你实际上需要枚举的数值。

如果你不这样做,只是需要一个string类型的枚举(这不是一个整型,所以不能是enum的基)这里有一个方法:

    static class AuthenticationMethod
    {
        public static readonly string
            FORMS = "Forms",
            WINDOWSAUTHENTICATION = "WindowsAuthentication";
    }

您可以使用与enum相同的语法来引用它

if (bla == AuthenticationMethod.FORMS)

它将比使用数值(比较字符串而不是数字)稍微慢一些,但从好的方面来看,它不使用反射(慢)来访问字符串。

试试type-safe-enum模式。

public sealed class AuthenticationMethod {

    private readonly String name;
    private readonly int value;

    public static readonly AuthenticationMethod FORMS = new AuthenticationMethod (1, "FORMS");
    public static readonly AuthenticationMethod WINDOWSAUTHENTICATION = new AuthenticationMethod (2, "WINDOWS");
    public static readonly AuthenticationMethod SINGLESIGNON = new AuthenticationMethod (3, "SSN");        

    private AuthenticationMethod(int value, String name){
        this.name = name;
        this.value = value;
    }

    public override String ToString(){
        return name;
    }

}

更新 显式(或隐式)类型转换可以通过

adding static field with mapping private static readonly Dictionary<string, AuthenticationMethod> instance = new Dictionary<string,AuthenticationMethod>(); n.b. In order that the initialisation of the the "enum member" fields doesn't throw a NullReferenceException when calling the instance constructor, be sure to put the Dictionary field before the "enum member" fields in your class. This is because static field initialisers are called in declaration order, and before the static constructor, creating the weird and necessary but confusing situation that the instance constructor can be called before all static fields have been initialised, and before the static constructor is called. filling this mapping in instance constructor instance[name] = this; and adding user-defined type conversion operator public static explicit operator AuthenticationMethod(string str) { AuthenticationMethod result; if (instance.TryGetValue(str, out result)) return result; else throw new InvalidCastException(); }

更新:访问这个页面,8年后,在很长一段时间没有接触c#之后,看起来我的答案不再是最好的解决方案。我非常喜欢与属性-函数绑定的转换器解决方案。

如果你正在阅读这篇文章,请确保你也查看了其他答案。(提示:它们在这个上面)


和你们大多数人一样,我非常喜欢Jakub Šturc所选的答案,但我也非常讨厌复制粘贴代码,并尽可能少地这样做。

因此,我决定使用一个EnumBase类,从其中继承/内置大部分功能,从而使我能够专注于内容而不是行为。

这种方法的主要问题是基于这样一个事实,即尽管Enum值是类型安全的实例,但交互是与Enum Class类型的静态实现进行的。 所以在泛型魔法的帮助下,我想我终于得到了正确的组合。 希望有人能像我一样觉得这个有用。

我将从Jakub的例子开始,但是使用继承和泛型:

public sealed class AuthenticationMethod : EnumBase<AuthenticationMethod, int>
{
    public static readonly AuthenticationMethod FORMS =
        new AuthenticationMethod(1, "FORMS");
    public static readonly AuthenticationMethod WINDOWSAUTHENTICATION =
        new AuthenticationMethod(2, "WINDOWS");
    public static readonly AuthenticationMethod SINGLESIGNON =
        new AuthenticationMethod(3, "SSN");

    private AuthenticationMethod(int Value, String Name)
        : base( Value, Name ) { }
    public new static IEnumerable<AuthenticationMethod> All
    { get { return EnumBase<AuthenticationMethod, int>.All; } }
    public static explicit operator AuthenticationMethod(string str)
    { return Parse(str); }
}

这里是基类:

using System;
using System.Collections.Generic;
using System.Linq; // for the .AsEnumerable() method call

// E is the derived type-safe-enum class
// - this allows all static members to be truly unique to the specific
//   derived class
public class EnumBase<E, T> where E: EnumBase<E, T>
{
    #region Instance code
    public T Value { get; private set; }
    public string Name { get; private set; }

    protected EnumBase(T EnumValue, string Name)
    {
        Value = EnumValue;
        this.Name = Name;
        mapping.Add(Name, this);
    }

    public override string ToString() { return Name; }
    #endregion

    #region Static tools
    static private readonly Dictionary<string, EnumBase<E, T>> mapping;
    static EnumBase() { mapping = new Dictionary<string, EnumBase<E, T>>(); }
    protected static E Parse(string name)
    {
        EnumBase<E, T> result;
        if (mapping.TryGetValue(name, out result))
        {
            return (E)result;
        }

        throw new InvalidCastException();
    }
    // This is protected to force the child class to expose it's own static
    // method.
    // By recreating this static method at the derived class, static
    // initialization will be explicit, promising the mapping dictionary
    // will never be empty when this method is called.
    protected static IEnumerable<E> All
    { get { return mapping.Values.AsEnumerable().Cast<E>(); } }
    #endregion
}

我想把这篇文章作为下面引用的帖子的评论,但不能,因为我没有足够的代表。代码包含一个错误,我想向试图使用这个解决方案的个人指出这一点:

[TypeConverter typeof (CustomEnumTypeConverter (typeof (MyEnum))) public enum MyEnum { //自定义类型转换器将使用description属性 [描述(“自定义描述”)] ValueWithCustomDescription, //这将完全暴露。 确切的 }

应该是

[TypeConverter(typeof(CustomEnumTypeConverter<MyEnum>))]
public enum MyEnum
{
  // The custom type converter will use the description attribute
  [Description("A custom description")]
  ValueWithCustomDescription,

  // This will be exposed exactly.
  Exact
}

我同意基斯的意见,但我还不能投票。

我使用一个静态方法和swith语句来返回我想要的结果。在数据库中,我存储tinyint和我的代码只使用实际的enum,所以字符串是为UI需求。经过大量的测试,这导致了最好的性能和最好的控制输出。

public static string ToSimpleString(this enum)
{
     switch (enum)
     {
         case ComplexForms:
             return "ComplexForms";
             break;
     }
}

public static string ToFormattedString(this enum)
{
     switch (enum)
     {
         case ComplexForms:
             return "Complex Forms";
             break;
     }
}

然而,根据某些说法,这可能会导致维护的噩梦和一些代码异味。我试着留意那些很长很多的枚举,或者那些经常变化的枚举。除此之外,这对我来说是一个很好的解决方案。