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  • 利用自定义特性实现List的多属性排序

    知道linq有order by的功能,但是还是动手研究了一下,算是多实践实践反射。这篇算是笔记,直接上代码:

    using System;
    using System.Collections.Concurrent;
    using System.Collections.Generic;
    using System.Diagnostics;
    using System.Linq;
    using System.Reflection;
    using System.Security.Cryptography;
    using System.Text;
    using System.Threading.Tasks;

    namespace TestMultiplePropertySort
    {
        class Program
        {
            static void Main(string[] args)
            {
                #region 简单测试数据
                var list = new List<MyClass>()
                {
                    new MyClass()
                    {
                        P1="h3",
                        P2=1,
                        P3=DateTime.Now
                    },
                    new MyClass()
                    {
                        P1="h2",
                        P2=3,
                        P3=DateTime.Now.AddHours(-1)
                    },
                    new MyClass()
                    {
                        P1="h1",
                        P2=2,
                        P3=DateTime.Now.AddHours(1)
                    },
                    new MyClass()
                    {
                        P1="h3",
                        P2=1,
                        P3=DateTime.Now
                    },
                    new MyClass()
                    {
                        P1="h1",
                        P2=1,
                        P3=DateTime.Now
                    },
                    new MyClass()
                    {
                        P1="h2",
                        P2=2,
                        P3=DateTime.Now.AddHours(1)
                    },
                };
                #endregion

                //调用多字段排序
                SortMutiplePropertyHelper<MyClass>.SortMutipleProperty(list);

                //可以复用
                SortMutiplePropertyHelper<MySecondClass>.SortMutipleProperty(new List<MySecondClass>());

                //输出排序结果
                list.ForEach(m => Trace.WriteLine(m.ToString()));
            }
        }

        public class MyClass
        {
            [SortOrder(0)]
            public string P1 { get; set; }

            [SortOrder(1)]
            public int P2 { get; set; }

            [SortOrder(2)]
            public DateTime P3 { get; set; }

            public override string ToString()
            {
                return P1.ToString() + "," + P2.ToString() + "," + P3.ToString();
            }
        }

        public class MySecondClass
        {
           
        }

        [AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = false)]
        public class SortOrderAttribute : Attribute
        {
            public int Order { get; set; }
            public SortOrderAttribute(int order)
            {
                this.Order = order;
            }
        }

        public class SortMutiplePropertyHelper<T> where T : class ,new()
        {
            /// <summary>
            /// 保存属性和顺序的字典
            /// </summary>
            public static readonly Dictionary<PropertyInfo, SortOrderAttribute> attrDic = new Dictionary<PropertyInfo, SortOrderAttribute>();

            static SortMutiplePropertyHelper()
            {
                //初始化order字段
                Type t = typeof(T);
                foreach (var prop in t.GetProperties())
                {
                    foreach (var sortOrderAttribute in prop.GetCustomAttributes(typeof(SortOrderAttribute), false))
                    {
                        if (sortOrderAttribute is SortOrderAttribute)
                        {
                            attrDic.Add(prop, sortOrderAttribute as SortOrderAttribute);
                            break;
                        }
                    }
                }
            }

            public static void SortMutipleProperty(List<T> list)
            {
                list.Sort((t1, t2) =>
                {
                    int result = 0;

                    foreach (var attr in  attrDic.OrderBy(key => key.Value.Order))
                    {
                        //这里简单的把属性转成字符串对比,比较靠谱的做法应当是针对不同的类型去做不同的比较。
                        string v1 = attr.Key.GetValue(t1).ToString();
                        string v2 = attr.Key.GetValue(t2).ToString();
                        result = v1.CompareTo(v2);
                        if (result != 0)
                        {
                            break;
                        }
                    }

                    return result;
                });
            }
        }
    }

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  • 原文地址:https://www.cnblogs.com/12taotie21/p/4340485.html
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