詳解C#實(shí)例化對象的三種方式及性能對比

更新時(shí)間：2020年12月11日 08:44:22 作者：背過手

這篇文章主要介紹了C#實(shí)例化對象的三種方式及性能對比，文中通過示例代碼介紹的非常詳細(xì)，對大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價(jià)值，需要的朋友們下面隨著小編來一起學(xué)習(xí)學(xué)習(xí)吧

前言

做項(xiàng)目過程中有個(gè)需求要實(shí)例化兩萬個(gè)對象并添加到List

中，這個(gè)過程大概需要1min才能加載完（傳參較多），于是開啟了代碼優(yōu)化之旅，再此記錄。

首先想到的是可能實(shí)例化比較耗時(shí)，于是開始對每種實(shí)例化方式進(jìn)行測試，過程如下

實(shí)例化方式

1、用 New 關(guān)鍵字實(shí)例化一個(gè)類

2、用 Activator 實(shí)例化一個(gè)類

3、用 Assembly 實(shí)例化一個(gè)類

代碼實(shí)現(xiàn)

測試環(huán)境：

vs2019 .NET Framework 4.7

Intel Core i7-10510U CPU

首先定義一個(gè)類Person

public class Person 
{ 
 public Person()
 {
 }
 public Person(string name)
 {
  Name = name;
 }
 public string Name { get; set; }
}

我們先在無參的構(gòu)造函數(shù)中實(shí)例化，每種方式進(jìn)行十次，每次實(shí)例化十萬次，代碼如下

static void Main(string[] args)
  {
   Console.WriteLine("實(shí)例化對象的耗時(shí)比較（單位：毫秒）");
   Console.Write("     ");
   for (int i = 1; i <= 10; i++)
    Console.Write("{0:G}", i.ToString().PadLeft(5));
   Console.Write("\n");
   Console.Write("InstanceByNew".PadRight(20));
   for (int i = 1; i <= 10; i++)
   {
    Person person = null;
    Stopwatch watch = new Stopwatch();
    watch.Start();
    for (int j = 0; j < 100000; j++)
     person = new Person();
    watch.Stop();
    Console.Write(watch.ElapsedMilliseconds.ToString().PadLeft(5));
   }
   Console.Write("\n");
   Console.Write("InstanceByActivator".PadRight(20));
   for (int i = 1; i <= 10; i++)
   {
    Type type = Type.GetType("ConsoleApp1.Person");
    Person person = null;

    Stopwatch watch = new Stopwatch();
    watch.Start();
    for (int j = 0; j < 100000; j++)
    {
     object obj = Activator.CreateInstance(type);
     person = obj as Person;
    }
    watch.Stop();
    Console.Write(watch.ElapsedMilliseconds.ToString().PadLeft(5));
   }
   Console.Write("\n");
   Console.Write("InstanceByAssembly".PadRight(20));
   for (int i = 1; i <= 10; i++)
   {
    Assembly assembly = Assembly.Load("InstancePerformance");
    Person person = null;

    Stopwatch watch = new Stopwatch();
    watch.Start();
    for (int j = 0; j < 100000; j++)
    {
     object obj = assembly.CreateInstance("ConsoleApp1.Person");
     person = obj as Person;
    }
    watch.Stop();
    Console.Write(watch.ElapsedMilliseconds.ToString().PadLeft(5));
   }
   Console.Write("\n");
   Console.ReadKey();
  }

執(zhí)行結(jié)果如下：

然后來看下有參構(gòu)造函數(shù)中實(shí)例化的代碼和結(jié)果

static void Main(string[] args)
  {
   Console.WriteLine("實(shí)例化對象的耗時(shí)比較（單位：毫秒）");
   Console.Write("     ");
   for (int i = 1; i <= 10; i++)
    Console.Write("{0:G}", i.ToString().PadLeft(5));
   Console.Write("\n");
   Console.Write("InstanceByNew".PadRight(20));
   for (int i = 1; i <= 10; i++)
   {
    Person person = null;
    Stopwatch watch = new Stopwatch();
    watch.Start();
    for (int j = 0; j < 100000; j++)
     person = new Person("Test"+j);
    watch.Stop();
    Console.Write(watch.ElapsedMilliseconds.ToString().PadLeft(5));
   }
   Console.Write("\n");
   Console.Write("InstanceByActivator".PadRight(20));
   for (int i = 1; i <= 10; i++)
   {
    Type type = Type.GetType("ConsoleApp1.Person");
    Person person = null;

    Stopwatch watch = new Stopwatch();
    watch.Start();
    for (int j = 0; j < 100000; j++)
    {
     object obj = Activator.CreateInstance(type,new object[]{"Test"+j});
     person = obj as Person;
    }
    watch.Stop();
    Console.Write(watch.ElapsedMilliseconds.ToString().PadLeft(5));
   }
   Console.Write("\n");
   Console.Write("InstanceByAssembly".PadRight(20));
   for (int i = 1; i <= 10; i++)
   {
    Assembly assembly = Assembly.Load("InstancePerformance");
    Person person = null;

    Stopwatch watch = new Stopwatch();
    watch.Start();
    for (int j = 0; j < 100000; j++)
    {
     object obj = assembly.CreateInstance("ConsoleApp1.Person", true, System.Reflection.BindingFlags.Default, null, new []{"Test"+j}, null, null);
     person = obj as Person;
    }
    watch.Stop();
    Console.Write(watch.ElapsedMilliseconds.ToString().PadLeft(5));
   }
   Console.Write("\n");
   Console.ReadKey();
  }

執(zhí)行結(jié)果如下：