如何在（字符串，标志列表，带标志的枚举）之间转换枚举？

Question

如何从枚举转换为字符串，反之亦然？

考虑到枚举可以包含多个标志的情况，如何获得枚举包含的所有标志的列表？

Answer 1

Update 2

有一个库可以实现从枚举中获得的大部分功能，具有更好的性能https://github.com/TylerBrinkley/Enums.NET

---

从Enum到String：[Enum Instance].ToString();

示例：using System.Windows.Input;

ModifierKeys mk = ModifierKeys.None | ModifierKeys.Alt | ModifierKeys.Shift | ModifierKeys.Control;
mk.Tostring();

收益：

Alt, Control, Shift注意：“无”标志被删除

---

从字符串到Enum：

Enum.TryParse([(string) value],out [store variable]); 要么 Enum.Parse(typeof([Enum Type]), [(string) value], [(bool) should ignore character case ?]);

示例：using System.Windows.Input;

// Way 1:
ModifierKeys outenum;
bool successful = Enum.TryParse("None,Alt,Control,Shift", out outenum);

Console.WriteLine($"Is Successful ? : {successful}, result : {outenum.ToString()}");

结果：Is Successful ? : True, result : Alt, Control, Shift

要么

// Way 2:
ModifierKeys outenum = (ModifierKeys)Enum.Parse(typeof(ModifierKeys), "None,Alt,Control,Shift", true);
Console.WriteLine(outenum.ToString());

结果：Alt, Control, Shift

---

从Enum Flags到List

例：

        ModifierKeys mk = ModifierKeys.None | ModifierKeys.Alt | ModifierKeys.Shift | ModifierKeys.Control;
        List<ModifierKeys> mklist =
            mk
            .ToString() // Convert the enum to string
            .Split(new[] { "," } , StringSplitOptions.RemoveEmptyEntries) // Converts the string to Enumerable of string
            .Select(//converts each element of the list to an enum, and makes an Enumerable out of the newly-converted items
                strenum =>
                {
                    ModifierKeys outenum;
                    Enum.TryParse(strenum , out outenum);
                    return outenum;
                })
            .ToList(); // Creates a List from the Enumerable

结果：{ModifierKeys.Alt , ModifierKeys.Shift , ModifierKeys.Control}

---

从枚举标志列表到枚举

例：

 ModifierKeys[] mk = {ModifierKeys.None, ModifierKeys.Alt, ModifierKeys.Control, ModifierKeys.Shift};
 ModifierKeys mkc = mk.Aggregate((prev, next) => prev | next);
 Console.WriteLine(mkc.ToString());

结果：Alt, Control, Shift

---

从字符串列表到枚举

例：

    string[] mk = {"None", "Alt", "Control", "Shift"};
    ModifierKeys mkc = mk.Select(x => {ModifierKeys outenum; Enum.TryParse(x, out outenum); return outenum;}).Aggregate((prev , next) => prev | next);
    Console.WriteLine(mkc.ToString());

结果：Alt, Control, Shift

---

General notes:

• 在从字符串转换为Enum时使用方式1是首选，因为如果方式2失败则抛出异常，但如果方式1失败则返回false
• 在分析枚举字符串时分隔枚举标志时，仅使用,分隔符
• 在枚举字符串中的标志之间有空格无关紧要，所以"None , Alt,Control, Shift" = "None,Alt,Control,Shift"

---

UPDATE 1 :

我写了一个简单的Generic EnumConverter类，可以节省你的时间

public class EnumConverter<T> where T : struct, IConvertible, IFormattable
{
    private Type EnumType { get; set; }

    public Type UnderlyingType
    {
        get
        {
            return Enum.GetUnderlyingType(EnumType);
        }
    }
    public EnumConverter()
    {
        if (typeof(T).IsEnum)
            EnumType = typeof(T);
        else
            throw new ArgumentException("Provided type must be an enum");
    }
    public IEnumerable<T> ToFlagsList(T FromSingleEnum)
    {
        return FromSingleEnum.ToString()
        .Split(new[] { "," } , StringSplitOptions.RemoveEmptyEntries)
        .Select(
            strenum =>
            {
                T outenum = default(T);
                Enum.TryParse(strenum , true , out outenum);
                return outenum;
            });
    }
    public IEnumerable<T> ToFlagsList(IEnumerable<string> FromStringEnumList)
    {
        return FromStringEnumList
        .Select(
            strenum =>
            {
                T outenum = default(T);
                Enum.TryParse(strenum , true , out outenum);
                return outenum;
            });
    }

    public T ToEnum(string FromString)
    {
        T outenum = default(T);
        Enum.TryParse(FromString , true , out outenum);
        return outenum;
    }
    public T ToEnum(IEnumerable<T> FromListOfEnums)
    {
        var provider = new NumberFormatInfo();
        var intlist = FromListOfEnums.Select(x => x.ToInt32(provider));
        var aggregatedint = intlist.Aggregate((prev , next) => prev | next);
        return (T)Enum.ToObject(EnumType , aggregatedint);
    }
    public T ToEnum(IEnumerable<string> FromListOfString)
    {
        var enumlist = FromListOfString.Select(x =>
        {
            T outenum = default(T);
            Enum.TryParse(x , true , out outenum);
            return outenum;
        });
        return ToEnum(enumlist);
    }

    public string ToString(T FromEnum)
    {
        return FromEnum.ToString();
    }
    public string ToString(IEnumerable<T> FromFlagsList)
    {
        return ToString(ToEnum(FromFlagsList));
    }

    public object ToUnderlyingType(T FromeEnum)
    {
        return Convert.ChangeType(FromeEnum , UnderlyingType);
    }
}

用法：

 EnumConverter<ModifierKeys> conv = new EnumConverter<ModifierKeys>();
 //conv.ToEnum
 //conv.ToFlagsList
 //conv.ToString