c# - 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？

假设枚举可以包含多个标志，我如何才能获得一个枚举包含的所有标志的列表？

Answer 1

更新2

有一个库可以实现枚举所需的大部分功能，而且性能更好 https://github.com/TylerBrinkley/Enums.NET

---

从枚举到字符串: [Enum Instance].ToString();

示例:使用 System.Windows.Input;

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

返回:

Alt、Control、Shift注意:“无”标志已删除

---

从字符串到枚举:

Enum.TryParse([(string) value],out [store variable]);
或者
Enum.Parse(typeof([Enum Type]), [(string) value], [(bool) 应该忽略字符大小写？]);

示例:使用 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:是否成功？ : True, 结果 : Alt, Control, Shift

或

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

结果:Alt、Control、Shift

---

从枚举标志到列表

例子:

        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

例子:

 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

例子:

    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

---

一般注意事项:

• 字符串转枚举优先使用方式一，因为方式二失败会抛出异常，方式一失败则返回false
• 在解析枚举字符串时分隔枚举标志时，仅使用, 分隔符
• 枚举字符串中的标志之间有空格无关紧要，所以“无，Alt，Control，Shift” = “无，Alt，Control，Shift”

---

更新 1:

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

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