.NET core高性能對(duì)象轉(zhuǎn)換示例代碼

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.NET core高性能對(duì)象轉(zhuǎn)換示例代碼

.NET core高性能對(duì)象轉(zhuǎn)換示例代碼:前言 NET Core(開放源代碼,跨平臺(tái),x-copy可部署等)有許多令人興奮的方面,其中最值得稱贊的就是其性能了。關(guān)于對(duì)象轉(zhuǎn)換已經(jīng)有不少輪子(AutoMapper,TinyMapper) .出于項(xiàng)目需要，手動(dòng)造一個(gè)簡單輪子。下面話不多說了，來一起看看詳細(xì)的介紹吧。示例代碼 g&

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導(dǎo)讀.NET core高性能對(duì)象轉(zhuǎn)換示例代碼:前言 NET Core(開放源代碼,跨平臺(tái),x-copy可部署等)有許多令人興奮的方面,其中最值得稱贊的就是其性能了。關(guān)于對(duì)象轉(zhuǎn)換已經(jīng)有不少輪子(AutoMapper,TinyMapper) .出于項(xiàng)目需要，手動(dòng)造一個(gè)簡單輪子。下面話不多說了，來一起看看詳細(xì)的介紹吧。示例代碼 g&

前言

NET Core(開放源代碼,跨平臺(tái),x-copy可部署等)有許多令人興奮的方面,其中最值得稱贊的就是其性能了。關(guān)于對(duì)象轉(zhuǎn)換已經(jīng)有不少輪子(AutoMapper,TinyMapper) .出于項(xiàng)目需要，手動(dòng)造一個(gè)簡單輪子。下面話不多說了，來一起看看詳細(xì)的介紹吧。

示例代碼

g>1.采用靜態(tài)泛型類緩存，避免了拆箱裝箱操作。

2.對(duì)于轉(zhuǎn)換對(duì)象中有，字段名一樣但是類型不一樣的類時(shí)仍可以用

public static class Mapper<TSource, TTarget> where TSource : class where TTarget : class
 {
 public readonly static Func<TSource, TTarget> Map;

 static Mapper()
 {
 if (Map == null)
 Map = GetMap();
 }

 private static Func<TSource, TTarget> GetMap()
 {
 var sourceType = typeof(TSource);
 var targetType = typeof(TTarget);

 var parameterExpression = Expression.Parameter(sourceType, "p");
 var memberInitExpression = GetExpression(parameterExpression, sourceType, targetType);

 var lambda = Expression.Lambda<Func<TSource, TTarget>>(memberInitExpression, parameterExpression);
 return lambda.Compile();
 }

 /// <summary>
 /// 根據(jù)轉(zhuǎn)換源和目標(biāo)獲取表達(dá)式樹
 /// </summary>
 /// <param name="parameterExpression">表達(dá)式參數(shù)p</param>
 /// <param name="sourceType">轉(zhuǎn)換源類型</param>
 /// <param name="targetType">轉(zhuǎn)換目標(biāo)類型</param>
 /// <returns></returns>
 private static MemberInitExpression GetExpression(Expression parameterExpression, Type sourceType, Type targetType)
 {
 var memberBindings = new List<MemberBinding>();
 foreach (var targetItem in targetType.GetProperties().Where(x => x.PropertyType.IsPublic && x.CanWrite))
 {
 var sourceItem = sourceType.GetProperty(targetItem.Name);

 //判斷實(shí)體的讀寫權(quán)限
 if (sourceItem == null || !sourceItem.CanRead || sourceItem.PropertyType.IsNotPublic)
 continue;

 //標(biāo)注NotMapped特性的屬性忽略轉(zhuǎn)換
 if (sourceItem.GetCustomAttribute<NotMappedAttribute>() != null)
 continue;

 var propertyExpression = Expression.Property(parameterExpression, sourceItem);

 //判斷都是class 且類型不相同時(shí)
 if (targetItem.PropertyType.IsClass && sourceItem.PropertyType.IsClass && targetItem.PropertyType != sourceItem.PropertyType)
 {
 if (targetItem.PropertyType != targetType)//防止出現(xiàn)自己引用自己無限遞歸
 {
 var memberInit = GetExpression(propertyExpression, sourceItem.PropertyType, targetItem.PropertyType);
 memberBindings.Add(Expression.Bind(targetItem, memberInit));
 continue;
 }
 }

 if (targetItem.PropertyType != sourceItem.PropertyType)
 continue;

 memberBindings.Add(Expression.Bind(targetItem, propertyExpression));
 }
 return Expression.MemberInit(Expression.New(targetType), memberBindings);
 }
 }

3.調(diào)用方法如下

（1）構(gòu)造樣例類

public class A
{
 public int Id { get; set; }
 public string Name { get; set; }
 public C User { get; set; }
 
 /// <summary>
 /// 標(biāo)注為notmapped特性時(shí)，不轉(zhuǎn)換賦值
 /// </summary>
 [System.ComponentModel.DataAnnotations.Schema.NotMapped]
 public D UserA { get; set; }
 
}
 
public class B
{
 public int Id { get; set; }
 public string Name { get; set; }
 public D User { get; set; }<br data-filtered="filtered">
 public D UserA { get; set; }
}
 
public class C
{
 public int Id { get; set; }
 public string Name { get; set; }
}
 
public class D
{
 public int Id { get; set; }
 public string Name { get; set; }
}

(2) 調(diào)用

var a = new A
{
 Id = 1,
 Name = "張三",
 User = new C
 {
 Id = 1,
 Name = "李四"
 }
};<br>
B b = Mapper<A, B>.Map(a);//得到轉(zhuǎn)換結(jié)果

4.性能測試

var length = 10000000;
 var listA = new List<A>();
 for (int i = 0; i < length; i++)
 {
 listA.Add(new A
 {
 Id = i,
 Name = "張三",
 User = new C
 {
 Id = i,
 Name = "李四"
 }
 });
 }

 var sw = Stopwatch.StartNew();
 for (int i = 0; i < length; i++)
 {
 var item = listA[i];
 var b = new B
 {
 Id = item.Id,
 Name = item.Name,
 User = new D
 {
 Id = i,
 Name = "李四",
 }
 };
 }
 sw.Stop();
 Console.WriteLine($"原生的時(shí)間:{sw.ElapsedMilliseconds}ms");

 //表達(dá)式
 Mapper<A, B>.Map(listA[0]);//預(yù)先編譯緩存
 sw.Restart();
 for (int i = 0; i < length; i++)
 {
 Mapper<A, B>.Map(listA[i]);
 }
 sw.Stop();
 Console.WriteLine($"表達(dá)式的時(shí)間:{sw.ElapsedMilliseconds}ms");

 //AutoMapper
 AutoMapper.Mapper.Initialize(cfg => cfg.CreateMap<A, B>());
 sw.Restart();
 for (int i = 0; i < length; i++)
 {
 var b = AutoMapper.Mapper.Map<B>(listA[i]);
 }
 sw.Stop();
 Console.WriteLine($"AutoMapper時(shí)間:{sw.ElapsedMilliseconds}ms");

 //TinyMapper
 TinyMapper.Bind<A, B>();
 sw.Restart();
 for (int i = 0; i < length; i++)
 {
 var b = TinyMapper.Map<B>(listA[i]);
 }
 sw.Stop();
 Console.WriteLine($"TinyMapper時(shí)間:{sw.ElapsedMilliseconds}ms");

 Console.ReadLine();

5. 1000萬數(shù)據(jù)不帶子類集結(jié)果