渐谈枚举(Enum)的高级应用

今天碰到枚举是一直没有见过的。我们经常使用枚举，但是可能只是一些简单的应用，其实在我们的项目中用到的 下拉列表、Model属性类型等，都可以利用枚举更好的实现。 

enum Days { Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday };

 

我们平时定义枚举

//今天所见定义枚举  

public enum TypeStatus
{

[Description("待审核")]
Pending = 1,


[Description("审核通过")]
Audited = 2,

｝

 

      //获取枚举值   

   

   (int)model.Department

 

 

     //获取枚举描述信息    

     EnumHelper.GetEnumDescription(model.Department)

 

 

 

 

1、下拉列表使用枚举数据源：

• var deList = EnumHelper.GetCachedDictionary(typeof(TypeStatus));  
      var ddlDeList = new List<SelectListItem>();  
      ddlDeList.Add(new SelectListItem() { Text = "请选择", Value = "-1" });  
      foreach (var item in detList)  
      {  
          ddlDeList.Add(new SelectListItem() { Text = item.Value, Value = item.Key });  
      }  
   

   

以下是枚举帮助类    

• EnumHelper.cs  
  public static class EnumHelper  
   {  
    private static readonly Hashtable ht = Hashtable.Synchronized(new Hashtable());  
    /// 从缓存中获取枚举对应的List  
    /// </summary>  
    /// <param name="type"></param>  
    /// <returns></returns>  
    public static IList<KeyValuePair<string, string>> GetCachedDictionary(Type type)  
    {  
     if (ht.Contains(type))  
     {  
      return ht[type] as IList<KeyValuePair<string, string>>;  
     }  
     else  
     {  
      IList<KeyValuePair<string, string>> dict = GetDictionary(type);  
      ht[type] = dict;  
      return dict;  
     }  
    }  public static IList<KeyValuePair<string, string>> GetDictionary(Type type)  
    {  
              if (!type.IsEnum)   
              {  
                  throw new InvalidOperationException("错误的枚举类型");  
              }  
     FieldInfo[] fields = type.GetFields();  
     IList<KeyValuePair<string, string>> dict = new List<KeyValuePair<string, string>>();  
              foreach (var item in fields)  
              {  
                  if (item.FieldType.IsEnum == false) { continue; }  
      string desription = string.Empty;  
      object[] objs = item.GetCustomAttributes(typeof (DescriptionAttribute), false);  
      if (objs != null && objs.Length> 0)  
      {  
       DescriptionAttribute da = (DescriptionAttribute) objs[0];  
  desription = da.Description;  
      }  
      else  
      {  
  desription = item.Name;  
      }  
      dict.Add(new KeyValuePair<string, string>(((int) Enum.Parse(type, item.Name)).ToString(), desription));  
     }  
     return dict;  
    }  public static string GetCachedDescription(Type type, string fieldName)  
    {  
     IList<KeyValuePair<string, string>> dictionary = GetCachedDictionary(type);  
     foreach (KeyValuePair<string, string> keyValuePair in dictionary)  
     {  
      if (keyValuePair.Key == ((int) (Enum.Parse(type, fieldName))).ToString())  
      {  
       return keyValuePair.Value;  
      }  
     }  
     return fieldName;  
    }  public static string GetCachedFieldName(Type type, string description)  
    {  
     IList<KeyValuePair<string, string>> dictionary = GetCachedDictionary(type);  
     foreach (KeyValuePair<string, string> keyValuePair in dictionary)  
     {  
      if(keyValuePair.Value == description)  
      {  
       return keyValuePair.Key;  
      }  
     }  
     return description;  
    }      
          ///<summary>  
          /// 根据枚举类型获取描述  
          ///</summary>  
          ///<param name="enumSubitem">类型</param>  
          ///<returns>描述</returns>  
          public static string GetEnumDescription(Enum value)  
          {  
              // Get the Description attribute value for the enum value  
              FieldInfo fi = value.GetType().GetField(value.ToString());  
              DescriptionAttribute[] attributes = (DescriptionAttribute[])fi.GetCustomAttributes(typeof(DescriptionAttribute), false);  
              if (attributes.Length > 0)  
              {  
                  return attributes[0].Description;  
              }  
              else  
              {  
                  return value.ToString();  
              }  
          }       
          /// <summary>  
          /// 从缓存中获取枚举对应的List[添加一空白列]  
          /// </summary>  
          /// <param name="type"></param>  
          /// <returns></returns>  
          public static IList<KeyValuePair<string, string>> GetCachedDictionaryBlank(Type type)  
          {  
              if (ht.Contains(type))  
              {  
                  return ht[type] as IList<KeyValuePair<string, string>>;  
              }  
              IList<KeyValuePair<string, string>> dict = GetDictionary(type);  
              dict.Insert(0, new KeyValuePair<string, string>((-1).ToString(), string.Empty));  
              ht[type] = dict;  
              return dict;  
          }        public static KeyValuePair<string, string> GetEnum(Type type, string fieldName)  
          {  
              KeyValuePair<string, string> kvp = new KeyValuePair<string, string>();  
              IList<KeyValuePair<string, string>> dictionary = GetCachedDictionary(type);  
              foreach (KeyValuePair<string, string> keyValuePair in dictionary)  
              {  
                  if (keyValuePair.Key == ((int)(Enum.Parse(type, fieldName))).ToString())  
                  {  
  kvp = keyValuePair;  
                      break;  
                  }  
              }  
              return kvp;  
          }  
   }