【转载】对象克隆（C# 快速高效率复制对象另一种方式 表达式树转）

Linqpad 代码

Benmarker测试结果耗时改善很明显，而且还可以支持深度复制，看来果然很优秀

// * Summary *

BenchmarkDotNet=v0.12.0, OS=Windows 10.0.18362

Intel Core i7-9700 CPU 3.00GHz, 1 CPU, 8 logical and 8 physical cores

.NET Core SDK=3.1.201

  [Host] : .NET Core 3.1.3 (CoreCLR 4.700.20.11803, CoreFX 4.700.20.12001), X64 RyuJIT

|              Method |           Mean |         Error |      StdDev |
|

-------------------- |---------------:|--------------:|------------:|

| TestTransReflection |   1,204.881 ns |    23.2975 ns |  23.9248 ns |
|      TestExpression | 122,195.921 ns | 1,007.6728 ns | 942.5777 ns |
|        TestTransExp |     250.915 ns |     2.1132 ns |   1.9767 ns |
|      TestTransExpV2 |       9.475 ns |     0.2525 ns |   0.2362 ns |
|       TestAutoMappe |     176.756 ns |     3.5712 ns |   3.6673 ns |

 

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<Query Kind="Program">   <Reference Relative="..\..\Libs\AutoMapper.9.0.0\lib\netstandard2.0\AutoMapper.dll">D:\projects\github\sui84\linqpad\LINQPad Queries\Libs\AutoMapper.9.0.0\lib\netstandard2.0\AutoMapper.dll</Reference>   <NuGetReference>BenchmarkDotNet</NuGetReference>   <Namespace>AutoMapper</Namespace>   <Namespace>BenchmarkDotNet.Attributes</Namespace>   <Namespace>BenchmarkDotNet.Running</Namespace>   <Namespace>System.Security.Cryptography</Namespace>   <Namespace>System.Windows.Forms.DataVisualization.Charting</Namespace> </Query>   #LINQPad optimize+ /*   对象克隆（C# 快速高效率复制对象另一种方式 表达式树转） https://www.cnblogs.com/lsgsanxiao/p/8205096.html */   void Main() {     Student s = InitStudent();     //StudentSecond ss= TransReflection<Student, StudentSecond>(s);     StudentSecond ss= TransExpV2<Student, StudentSecond>.Trans(s);     ss.Dump();           var summary = BenchmarkRunner.Run<CloneBenchmarks>();        }   public static Student InitStudent(){     List<Address> studentAddress = new List<Address>();     studentAddress.Add(new Address(){address="testaddress1"});     studentAddress.Add(new Address(){address="testaddress2"});     Student s = new Student() { Age = 20, Id = 1, Name = "Emrys" , StudentAddress = studentAddress};     return s; }   public class Student {     public int Id { get; set; }     public string Name { get; set; }     public int Age { get; set; }     public List<Address> StudentAddress { get; set; } }   public class StudentSecond {     public int Id { get; set; }     public string Name { get; set; }     public int Age { get; set; }     public List<Address> StudentAddress { get; set; } }   public class Address {     public string address { get; set; } }     public class CloneBenchmarks {     AutoMapper.IMapper _mapper;     Student _s;     public CloneBenchmarks(){         var config = new MapperConfiguration(cfg => {         cfg.CreateMap<Student, StudentSecond>();         cfg.CreateMap<Address, Address>();         });         config.AssertConfigurationIsValid();         _mapper = config.CreateMapper();          _s = InitStudent();     }       [Benchmark]     public object TestTransReflection(){         StudentSecond ss= TransReflection<Student, StudentSecond>(_s);         return ss;     }           [Benchmark]     public object TestExpression(){         Expression<Func<Student, StudentSecond>> ss = (x) => new StudentSecond { Age = x.Age, Id = x.Id, Name = x.Name , StudentAddress = x.StudentAddress };         var f = ss.Compile();         StudentSecond studentSecond = f(_s);         return studentSecond;     }           private static Dictionary<string, object> _Dic = new Dictionary<string, object>();         [Benchmark]     public object TestTransExp(){         StudentSecond ss= TransExp<Student, StudentSecond>(_s);         return ss;     }           [Benchmark]     public object TestTransExpV2(){         StudentSecond ss= TransExpV2<Student, StudentSecond>.Trans(_s);         return ss;     }           [Benchmark]     public object TestAutoMappe(){         var ss = _mapper.Map<Student, StudentSecond>(_s);         return ss;     }           public  TOut TransReflection<TIn, TOut>(TIn tIn)     {         TOut tOut = Activator.CreateInstance<TOut>();         var tInType = tIn.GetType();         foreach (var itemOut in tOut.GetType().GetProperties())         {             var itemIn = tInType.GetProperty(itemOut.Name); ;             if (itemIn != null)             {                 itemOut.SetValue(tOut, itemIn.GetValue(tIn));             }         }         return tOut;     }          private static TOut TransExp<TIn, TOut>(TIn tIn)     {         string key = string.Format("trans_exp_{0}_{1}", typeof(TIn).FullName, typeof(TOut).FullName);         if (!_Dic.ContainsKey(key))         {             ParameterExpression parameterExpression = Expression.Parameter(typeof(TIn), "p");             List<MemberBinding> memberBindingList = new List<MemberBinding>();               foreach (var item in typeof(TOut).GetProperties())             {                    if (!item.CanWrite)                 continue;                 MemberExpression property = Expression.Property(parameterExpression, typeof(TIn).GetProperty(item.Name));                 MemberBinding memberBinding = Expression.Bind(item, property);                 memberBindingList.Add(memberBinding);             }               MemberInitExpression memberInitExpression = Expression.MemberInit(Expression.New(typeof(TOut)), memberBindingList.ToArray());             Expression<Func<TIn, TOut>> lambda = Expression.Lambda<Func<TIn, TOut>>(memberInitExpression, new ParameterExpression[] { parameterExpression });             Func<TIn, TOut> func = lambda.Compile();               _Dic[key] = func;         }         return ((Func<TIn, TOut>)_Dic[key])(tIn);     }           }   public static class TransExpV2<TIn, TOut> {       private static readonly Func<TIn, TOut> cache = GetFunc();     private static Func<TIn, TOut> GetFunc()     {         ParameterExpression parameterExpression = Expression.Parameter(typeof(TIn), "p");         List<MemberBinding> memberBindingList = new List<MemberBinding>();           foreach (var item in typeof(TOut).GetProperties())         { if (!item.CanWrite) continue;               MemberExpression property = Expression.Property(parameterExpression, typeof(TIn).GetProperty(item.Name));             MemberBinding memberBinding = Expression.Bind(item, property);             memberBindingList.Add(memberBinding);         }           MemberInitExpression memberInitExpression = Expression.MemberInit(Expression.New(typeof(TOut)), memberBindingList.ToArray());         Expression<Func<TIn, TOut>> lambda = Expression.Lambda<Func<TIn, TOut>>(memberInitExpression, new ParameterExpression[] { parameterExpression });           return lambda.Compile();     }           public static TOut Trans(TIn tIn)     {         return cache(tIn);     } }