前言

做项目过程中有个需求要实例化两万个对象并添加到List

中，这个过程大概需要1min才能加载完（传参较多），于是开启了代码优化之旅，再此记录。

首先想到的是可能实例化比较耗时，于是开始对每种实例化方式进行测试，过程如下

实例化方式

1、用 New 关键字实例化一个类

2、用 Activator 实例化一个类

3、用 Assembly 实例化一个类

代码实现

测试环境：

vs2019 .NET Framework 4.7

Intel Core i7-10510U CPU

首先定义一个类Person

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

我们先在无参的构造函数中实例化，每种方式进行十次，每次实例化十万次，代码如下

static void Main(string[] args)
  {
   Console.WriteLine("实例化对象的耗时比较（单位：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();
  }

执行结果如下：

然后来看下有参构造函数中实例化的代码和结果

static void Main(string[] args)
  {
   Console.WriteLine("实例化对象的耗时比较（单位：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; 【文章由：韩国高防服务器 提供,感谢支持】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();
  }

执行结果如下：

 

结论

从上面的执行结果可以看出这三种方式的性能排序为

New > Activator > Assembly

但使用哪种方法还要视情况而定

后续

以上可以看出New性能最高，而我就是使用的New，问题还没解决，把问题指向判断List是否存在某元素上，于是开始测试List中的Contains, Exists, Any，Where。详情请点击.

到此这篇关于C#实例化对象的三种方式及性能对比的文章就介绍到这了,更多相关C#实例化对象的三种方式及性能对比内容请搜索海外IDC网以前的文章或继续浏览下面的相关文章希望大家以后多多支持海外IDC网！