.Net5 - 定义枚举，在查询中巧妙的应用方式

枚举命名规则：

1、 枚举以复数的形式命名 => 例如性别  public enum Genders { }

2、状态 以Status结尾

枚举的扩展方法：还有其他博文

 

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using System; using System.ComponentModel; using System.Reflection;   namespace EnumDemo {     /// <summary>     /// 枚举扩展方法     /// </summary>     public static class EnumExtensions     {         /// <summary>         /// 根据枚举int值获取枚举名称         /// </summary>         /// <typeparam name="T">枚举类型</typeparam>         /// <param name="status">枚举值</param>         /// <returns></returns>         public static string GetEnumName<T>(this int status)         {             return Enum.GetName(typeof(T), status);         }             /// <summary>         /// 获取枚举变量值的 Description 属性         /// </summary>         /// <param name="obj">枚举变量</param>         /// <returns>如果包含 Description 属性，则返回 Description 属性的值，否则返回枚举变量值的名称</returns>         public static string GetDescription(this Enum obj)         {             return GetDescription(obj, false);         }           /// <summary>         /// 获取枚举变量值的 Description 属性         /// </summary>         /// <param name="obj">枚举变量</param>         /// <param name="isTop">是否改变为返回该类、枚举类型的头 Description 属性，而不是当前的属性或枚举变量值的 Description 属性</param>         /// <returns>如果包含 Description 属性，则返回 Description 属性的值，否则返回枚举变量值的名称</returns>         public static string GetDescription(this Enum obj, bool isTop)         {             if (obj == null)             {                 return string.Empty;             }             Type enumType = obj.GetType();             DescriptionAttribute dna;             if (isTop)             {                 dna = (DescriptionAttribute)Attribute.GetCustomAttribute(enumType, typeof(DescriptionAttribute));             }             else             {                 FieldInfo fi = enumType.GetField(System.Enum.GetName(enumType, obj));                 dna = (DescriptionAttribute)Attribute.GetCustomAttribute(                    fi, typeof(DescriptionAttribute));             }             if ((dna != null)                 && (string.IsNullOrEmpty(dna.Description) == false))             {                 return dna.Description;             }             return obj.ToString();         }     } }

　　

枚举的举例验证：

 

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using System.ComponentModel;   namespace EnumDemo {     /// <summary>     /// 枚举以复数的形式命名     /// </summary>     public enum Genders     {         /// <summary>         /// 女人         /// </summary>         [Description("女人")]         Woman = 0,         /// <summary>         /// 男人         /// </summary>         [Description("男人")]         Man = 1,         /// <summary>         /// 未知         /// </summary>         [Description("未知")]         Unknown = 2     } }

　　

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namespace EnumDemo {     public class EmployeeInfo     {         public EmployeeInfo(int empId, string empName, Genders gender)         {             EmpId = empId;             EmpName = empName;             Gender = gender;         }           /// <summary>         /// 编号         /// </summary>         public int EmpId { get; set; }           /// <summary>         /// 姓名         /// </summary>         public string EmpName { get; set; }           /// <summary>         /// 性别         /// </summary>         public Genders Gender { get; set; }           /// <summary>         /// 性别【汉化值】 此属性为只读get         /// </summary>         public string GenderName => Gender.GetDescription();           public override string ToString()         {             return $"编号：{EmpId}-姓名：{EmpName}-性别：{Gender}-性别【汉化值】：{GenderName}";         }     } }

　　

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using System; using System.Collections.Generic;   namespace EnumDemo {     class Program     {         /// <summary>         /// 初始化职员信息         /// </summary>         /// <returns></returns>         static IList<EmployeeInfo> CreateEmployeeInfos()         {             var employees = new List<EmployeeInfo>             {                 new EmployeeInfo(1, "张三", Genders.Man),                 new EmployeeInfo(2, "李四", Genders.Woman),                 new EmployeeInfo(3, "王五", Genders.Woman),                 new EmployeeInfo(4, "陈大", Genders.Man),                 new EmployeeInfo(5, "钱二", Genders.Unknown)             };             return employees;         }           static void Main(string[] args)         {             #region enum、int、string之间的相互转换             Genders manValue = Genders.Man;// => Man             //枚举转string             string manStr = manValue.ToString();//效率低 => Man             string manStr2 = Enum.GetName(typeof(Genders), manValue);// => Man             //int转string             int num = 0;             string manStr5 = Enum.GetName(typeof(Genders), 0);// => Woman             string manStr3 = num.GetEnumName<Genders>();// => Woman             //枚举转int             int number = (int)manValue;// => 1             int number2 = manValue.GetHashCode();// => 1             int number3 = Convert.ToInt32(manValue);// => 1             //string转枚举             Genders man = (Genders)Enum.Parse(typeof(Genders), "Man");// => Man             Genders woman = (Genders)Enum.Parse(typeof(Genders), "0");// => Woman             //string转int             int number5 = Convert.ToInt32(Enum.Parse(typeof(Genders), "Man"));// => 1             //int转枚举             Genders man2 = (Genders)1;// => Man             Genders woman2 = (Genders)Enum.ToObject(typeof(Genders), 0);// => Woman             #endregion               //返回查询数据展示枚举汉语字时             var employees = CreateEmployeeInfos();             foreach (var item in employees)             {                 Console.WriteLine(item.ToString());             }         }     } }