如何使用枚舉的屬性思考？

Question

我打開你的想法：我真的不喜歡這種用法。如何通過屬性將枚舉轉換爲字符串。但請小心我的問題StringValueAttribute也有不止一個構造函數字段。如何通過StringValueAttribute開發GetStringValue擴展方法？順祝商祺...

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 
using System.Reflection; 

namespace UsingAttributes 
{ 
     static void Main(string[] args) 
     { 
      Console.WriteLine(UserType.Login.GetStringValue()); 
      Console.Read(); 
     } 
    } 
    public enum UserType : int 
    { 
     [StringValueAttribute("xyz", "test")] 
     Login = 1 
    } 
    public class StringValueAttribute : Attribute 
    { 
     public string UserName { get; protected set; } 
     public string PassWord { get; protected set; } 
     public decimal Something { get; protected set; } 

      public StringValueAttribute(string Username, string Password,decimal something) 
     { 
      UserName = Username; 
      PassWord = Password; 
      Something =something; 
     } 
     public StringValueAttribute(string Username, string Password) 
     { 
      UserName = Username; 
      PassWord = Password; 
     } 
     public StringValueAttribute(string Username) 
     { 
      UserName = Username; 

     } 

    } 

    public static class Extentions 
    { 
     public static String[] GetStringValue(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 
      StringValueAttribute[] attribs = fieldInfo.GetCustomAttributes(
       typeof(StringValueAttribute), false) as StringValueAttribute[]; 

      // Return the first if there was a match. 


       PropertyInfo[] pi = attribs[0].GetType().GetProperties(); 
       String[] Vals = new String[pi.Length]; 
       int i = 0; 
       foreach (PropertyInfo item in pi) 
       { 
        // Vals[i] = How to return String[] 

       } 
      // i dislike return values one by one : attribs[0].UserName 
      //return attribs.Length > 0 ? attribs[0].UserName : null; // i have more values 
     } 
    } 
} 

Answer 1

首先注意decimal不能作爲一個屬性參數。您可以使用double或者您可以使用一個字符串，然後將其轉換爲小數。

你向GetStringValue（）如果你有

Object val = item.GetValue(attribs[0], null); 
    Vals[i++] = val != null ? val.ToString() : ""; 

更換

// Vals[i] = How to return String[] 

如果您使用的是C＃4.0中應該工作，你不需要三個構造函數。您可以使用可選的參數：

public StringValueAttribute(string Username, string Password = "nothing", double something = 0)   
{    
    ... 
}   

而在舊版本的C＃您可以使用OptionalAttribute：

public StringValueAttribute(string Username, [Optional] string Password, [Optional] double something)   
{    
    ... 
}   

Answer 2

我不得不說這是一種奇怪的方式做到這一點，但你只是需要更改您的代碼是這樣的：

static void Main(string[] args) 
     { 
      object[] Objects = UserType.Login.GetStringValue(); 
      for (int x = 0; x < Objects.Length; ++x) 
       Console.WriteLine(Objects[x].ToString()); 
      Console.Read(); 
     } 
    } 

    public static class Extentions 
    { 
     public static object[] GetStringValue(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 
      StringValueAttribute[] attribs = fieldInfo.GetCustomAttributes(
       typeof(StringValueAttribute), false) as StringValueAttribute[]; 

      // Return the first if there was a match. 

      object[] Vals = new object[3]; 
      Vals[0] = attribs[0].UserName; 
      Vals[1] = attribs[0].PassWord; 
      Vals[2] = attribs[0].Something; 
      return Vals; 
     } 
    }