C#枚举通用方法

1、定义枚举

public enum ApplyState//例如：定义一个审核状态的枚举，包含以下几种状态
{
     /// <summary>
     /// 等待审批
     /// </summary>
     [Description("等待审批")]
     WaitingForApproval = 1,

     /// <summary>
     /// 拒绝
     /// </summary>
     [Description("拒绝")]
     Reject = 2,

     /// <summary>
     /// 审批通过
     /// </summary>
     [Description("审批通过")]
     ApprovalThroughThe = 3,

     /// <summary>
     /// 取消申请
     /// </summary>
     [Description("取消申请")]
     CancelApply = 4,

}

2、通用方法类

public class EnumHelper
{
   /// <summary>
   ///  把枚举的描述和值绑定到DropDownList
   /// </summary>
   /// <param name="enumType"></param>
   /// <returns></returns>
   public static IEnumerable<SelectListItem> GetDataSoure(this Enum e)
　 {
   　  List<SelectListItem> selectList = new List<SelectListItem>();
       //获取字段信息
       System.Reflection.FieldInfo[] ms = e.GetType().GetFields();

    　 foreach (System.Reflection.FieldInfo f in ms)
       {
           //反射出自定义属性
           foreach (Attribute attr in f.GetCustomAttributes(true))
           {
               System.ComponentModel.DescriptionAttribute dscript = attr as System.ComponentModel.DescriptionAttribute;
               if (dscript != null)
               {
                   selectList.Add(new SelectListItem()
                   {
                       Text = dscript.Description,
                       Selected =(f.GetValue(e).ToString() == e.ToString()),
                       Value = (f.GetValue(e)).ToString()
                   });
               }
               break;
           }
       }
       return selectList;
   }

   /// <summary>
   /// 获取枚举的描述文本
   /// </summary>
   /// <param name="e">枚举成员</param>
   /// <returns></returns>
   public static string GetEnumDescription(this Enum e)
   {
       //获取字段信息
       System.Reflection.FieldInfo[] ms = e.GetType().GetFields();

       foreach (System.Reflection.FieldInfo f in ms)
       {
           //判断名称是否相等
           if (f.Name != e.ToString()) continue;

           //反射出自定义属性
           foreach (Attribute attr in f.GetCustomAttributes(true))
           {
               //类型转换找到一个Description，用Description作为成员名称
               System.ComponentModel.DescriptionAttribute dscript = attr as System.ComponentModel.DescriptionAttribute;
               if (dscript != null)
                   return dscript.Description;
           }
        }
        //如果没有检测到合适的注释，则用默认名称
        return e.ToString();
     }  
}

3、枚举转化问题

1、枚举转Int

     (int)ApplyStatee.WaitingForApproval;

   2、Int转枚举

    (1)可以强制转换将整型转换成枚举类型：ApplyState state= (ApplyState)2;//找到值为2的枚举、即ApplyState.Reject

    (2)利用Enum的静态方法ToObject

       public static Object ToObject(Type enumType,int value)

       ApplyState state= (ApplyState)Enum.ToObject(typeof(ApplyState), 2)，那么state即为ApplyState.Reject

   3、字符串转枚举

      ApplyState _Type = (ApplyState)Enum.Parse(typeof(ApplyState), "Reject");

   4、枚举转字符串

     （1）枚举转字符串比较容易，可以直接用ToString()方法：例如：ApplyState.Reject.ToString()

      (2)利用Enum的静态方法GetName与GetNames：

         public static string GetName(Type enumType,Object value)

         public static string[] GetNames(Type enumType)

         例如：Enum.GetName(typeof(ApplyState),2))与Enum.GetName(typeof(ApplyState), ApplyState.Reject))的值都是"Reject"

         Enum.GetNames(typeof(ApplyState))将返回枚举字符串数组

4、获取枚举的描述(Description)信息

调用上面的GetEnumDescription(Enum e)方法
例如：GetEnumDescription(ApplyState.Reject)，得到的是"拒绝"