• 枚举常用操作扩展方法


    完整代码在笔记结尾

    获取枚举描述

    public static string GetEnumDescription(this Enum en)
            {
                var type = en.GetType(); //获取类型
                var memberInfos = type.GetMember(en.ToString()); //获取成员
                if (memberInfos.Any())
                {
                    if (memberInfos[0].GetCustomAttributes(typeof(DescriptionAttribute), false) is DescriptionAttribute[] attrs && attrs.Length > 0)
                    {
                        return attrs[0].Description; //返回当前描述
                    }
                }
    
                return en.ToString();
            }
    

    获取枚举Display特性的名称

    原理与获取Description描述是一样的,都是先获取类型,再通过GetMember方法获取到每个成员到数组中,最后通过DisplayAttribute获取其属性,DisplayAttribute这个特性里面的属性可以在编写枚举成员时通过注解写入

    [Display(Name = "红", GroupName = "纯色")]
    [Description("红色")]
    Red = 1,
    [Display(Name = "橙红", GroupName = "混合色")]
    [Description("橙红色")]
    OriginRed = 2
    

    获取Display特性下的属性的代码例子:

    public static string GetDisplay(this Enum en)
            {
                var type = en.GetType(); //获取类型
                var memberInfos = type.GetMember(en.ToString()); //获取成员
                if (memberInfos.Any())
                {
                    if (memberInfos[0].GetCustomAttributes(typeof(DisplayAttribute), false) is DisplayAttribute[] attrs && attrs.Length > 0)
                    {
                        //var groupName= attrs[0].GroupName;
                        //var order = attrs[0].Order;
                        return attrs[0].Name; //返回当前描述
                    }
                }
    
                return en.ToString();
            }
    

    获取枚举列表以枚举值作为Key

    public static readonly ConcurrentDictionary<Type, Dictionary<int, string>> EnumNameValueDict = new ConcurrentDictionary<Type, Dictionary<int, string>>();
    
    public static Dictionary<int, string> GetEnumDictionary(this Type enumType)
            {
                if (!enumType.IsEnum)
                {
                    throw new Exception("传入的类型非枚举(Enum)类型");
                }
    
                var names = EnumNameValueDict.ContainsKey(enumType) ? EnumNameValueDict[enumType] : new Dictionary<int, string>();
                if (names.Count == 0)
                {
                    names = GetDictionaryItems(enumType);
                    EnumNameValueDict[enumType] = names;
                }
                return names;
            }
    

    根据枚举值获取枚举成员

    public static string ToMemberByValue(this int value, Type enumType)
            {
                if (!enumType.IsEnum)
                {
                    throw new Exception("给定的类型非枚举(Enum)类型");
                }
    
                var nvc = new NameValueCollection();
                var fields = enumType.GetFields();
                foreach (FieldInfo field in fields)
                {
                    if (field.FieldType.IsEnum)
                    {
                        var strValue = ((int)enumType.InvokeMember(field.Name, BindingFlags.GetField, null, null, null)).ToString();
                        nvc.Add(strValue, field.Name);
                    }
                }
                return nvc[value];
            }
    

    完整扩展类及使用示例

    using System;
    using System.Collections.Concurrent;
    using System.Collections.Generic;
    using System.Collections.Specialized;
    using System.ComponentModel;
    using System.ComponentModel.DataAnnotations;
    using System.Linq;
    using System.Reflection;
    using System.Text;
    using System.Threading.Tasks;
    using System.Xml.Linq;
    
    namespace 枚举
    {
        /// <summary>
        /// 枚举扩展类
        /// </summary>
        public static class EnumExtension
        {
            public static readonly ConcurrentDictionary<Type, Dictionary<int, string>> EnumNameValueDict = new ConcurrentDictionary<Type, Dictionary<int, string>>();
            private static readonly ConcurrentDictionary<Type, Dictionary<string, int>> EnumValueNameDict = new ConcurrentDictionary<Type, Dictionary<string, int>>();
    
            /// <summary>
            ///  获取枚举对象Key与显示名称的字典
            /// </summary>
            /// <param name="enumType">枚举类型</param>
            /// <returns>以值为Key,显示名称为Value的字典</returns>
            /// <exception cref="Exception">非枚举类型</exception>
            public static Dictionary<int, string> GetEnumDictionary(this Type enumType)
            {
                if (!enumType.IsEnum)
                {
                    throw new Exception("给定的类型非枚举(Enum)类型");
                }
    
                var names = EnumNameValueDict.ContainsKey(enumType) ? EnumNameValueDict[enumType] : new Dictionary<int, string>();
                if (names.Count == 0)
                {
                    names = GetDictionaryItems(enumType);
                    EnumNameValueDict[enumType] = names;
                }
                return names;
            }
    
            /// <summary>
            /// 根据枚举成员获取自定义属性EnumDisplayNameAttribute的属性DisplayName
            /// </summary>
            /// <param name="enumType"></param>
            /// <returns></returns>
            public static Dictionary<string, int> GetEnumDescriptionAndValue(this Type enumType)
            {
                return Enum.GetValues(enumType)
                    .Cast<object>()
                    .ToDictionary(e =>
                    GetEnumDescription(e as Enum),
                    e => (int)e);
            }
    
            /// <summary>
            /// 获取枚举对象的值内容
            /// </summary>
            /// <param name="enumType"></param>
            /// <param name="name"></param>
            /// <returns></returns>
            public static int GetEnumValue(this Type enumType, string name)
            {
                if (!enumType.IsEnum)
                {
                    throw new Exception("给定的类型非枚举(Enum)类型");
                }
    
                Dictionary<string, int> enumDict = GetValueNameItems(enumType);
                return enumDict.ContainsKey(name) ? enumDict[name] : enumDict.Select(d => d.Value).FirstOrDefault();
            }
    
            /// <summary>
            /// 根据枚举成员获取Description描述
            /// </summary>
            /// <param name="en"></param>
            /// <returns></returns>
            public static string GetEnumDescription(this Enum en)
            {
                var type = en.GetType(); //获取类型
                var memberInfos = type.GetMember(en.ToString()); //获取成员
                if (memberInfos.Any())
                {
                    if (memberInfos[0].GetCustomAttributes(typeof(DescriptionAttribute), false) is DescriptionAttribute[] attrs && attrs.Length > 0)
                    {
                        return attrs[0].Description; //返回当前描述
                    }
                }
    
                return en.ToString();
            }
    
            /// <summary>
            /// 根据枚举成员获取Display的属性Name
            /// </summary>
            /// <returns></returns>
            public static string GetEnumDisplay(this Enum en)
            {
                var type = en.GetType(); //获取类型
                var memberInfos = type.GetMember(en.ToString()); //获取成员
                if (memberInfos.Any())
                {
                    if (memberInfos[0].GetCustomAttributes(typeof(DisplayAttribute), false) is DisplayAttribute[] attrs && attrs.Length > 0)
                    {
                        return attrs[0].Name; //返回当前描述
                    }
                }
    
                return en.ToString();
            }
    
            /// <summary>
            /// 根据枚举值获取枚举成员
            /// </summary>
            /// <param name="value">枚举值</param>
            /// <param name="enumType">枚举类型</param>
            /// <returns></returns>
            public static string ToMemberByValue(this int value, Type enumType)
            {
                if (!enumType.IsEnum)
                {
                    throw new Exception("给定的类型非枚举(Enum)类型");
                }
    
                var nvc = new NameValueCollection();
                var fields = enumType.GetFields();
                foreach (FieldInfo field in fields)
                {
                    if (field.FieldType.IsEnum)
                    {
                        var strValue = ((int)enumType.InvokeMember(field.Name, BindingFlags.GetField, null, null, null)).ToString();
                        nvc.Add(strValue, field.Name);
                    }
                }
                return nvc[value];
            }
    
            #region 私有操作方法
            private static Dictionary<int, string> GetDictionaryItems(Type enumType)
            {
                var enumItems = enumType.GetFields(BindingFlags.Public | BindingFlags.Static);
                var names = new Dictionary<int, string>(enumItems.Length);
                foreach (FieldInfo enumItem in enumItems)
                {
                    int intValue = (int)enumItem.GetValue(enumType);
                    names[intValue] = enumItem.Name;
                }
    
                return names;
            }
    
            private static Dictionary<string, int> GetValueNameItems(Type enumType)
            {
                var enumItems = enumType.GetFields(BindingFlags.Public | BindingFlags.Static);
                var values = new Dictionary<string, int>(enumItems.Length);
                foreach (var enumItem in enumItems)
                {
                    values[enumItem.Name] = (int)enumItem.GetValue(enumType);
                }
    
                return values;
            }
    
            /// <summary>
            /// 根据枚举类型得到其所有的 值 与 枚举定义字符串 的集合
            /// </summary>
            /// <param name="enumType"></param>
            /// <returns></returns>
            private static NameValueCollection GetEnumStringFromEnumValue(Type enumType)
            {
                var nvc = new NameValueCollection();
                var fields = enumType.GetFields();
                foreach (FieldInfo field in fields)
                {
                    if (field.FieldType.IsEnum)
                    {
                        var strValue = ((int)enumType.InvokeMember(field.Name, BindingFlags.GetField, null, null, null)).ToString();
                        nvc.Add(strValue, field.Name);
                    }
                }
    
                return nvc;
            }
    
            #endregion
        }
    }
    
    

    使用示例:

    public class Program
        {
            static void Main(string[] args)
            {
                //使用示例:
                var dic1 = typeof(MyEnum).GetEnumDictionary(); //获取所有成员
                var dic2 = typeof(MyEnum).GetEnumDescriptionAndValue();  //获取所有成员(描述和值)
                var memberVal = typeof(MyEnum).GetEnumValue("Red");  //根据成员字符串获取枚举值
                var desc = MyEnum.Green.GetEnumDescription();  //根据枚举成员获取描述
                var displayStr = MyEnum.Green.GetEnumDisplay();  //根据枚举成员获取显示名称
                var member = 2.ToMemberByValue(typeof(MyEnum));  //根据枚举值获取枚举成员
            }
    
            public enum MyEnum
            {
                [Display(Name = "红", GroupName = "纯色")]
                [Description("红色")]
                Red = 1,
                [Display(Name = "绿")]
                [Description("绿色")]
                Green = 2,
                [Display(Name = "蓝")]
                [Description("蓝色")]
                Blue = 3,
    
            }
        }
    
  • 相关阅读:
    [每日一题]:小猫爬山
    [每日一题]:Wannafly挑战赛1 -- Treepath
    JavaWeb学习(19): 文件的上传和下载
    [每日一题]:牛客练习赛61 A:打怪
    [十二省联考2019]春节十二响——长链剖分+堆
    BZOJ4977[Lydsy1708月赛]跳伞求生——贪心+堆+模拟费用流
    BZOJ4003[JLOI2015]城池攻占——可并堆
    BZOJ1823[JSOI2010]满汉全席——2-SAT+tarjan缩点
    BZOJ3876[Ahoi2014&Jsoi2014]支线剧情——有上下界的最小费用最大流
    BZOJ2738矩阵乘法——整体二分+二维树状数组
  • 原文地址:https://www.cnblogs.com/chonglu/p/15631283.html
Copyright © 2020-2023  润新知