反射备忘
反射: 通过 System.Reflection 命名空间中的类以及 System..::.Type,您可以获取有关已加载的程序集和在其中定义的类型(如类、接口和值类型)的信息。您也可以使用反射在运行时创建类型实例,以及调用和访问这些实例。
namespace _Net的反射
{
public class Person {
public void Action() {
Console.WriteLine("People Run!");
}
}
class Program
{
static void Main(string[] args)
{
int times = 500000;
var p = new Person();
//获得类型的几种方法
Type t = typeof(Person);
t = Type.GetType("_Net的反射.Person");
t = p.GetType();
//实例化对象的各种方法
Stopwatch stop = new Stopwatch(); stop.Start();
for (int i = 0; i < times; i++)
{
var per = new Person();
}
stop.Stop();
Console.WriteLine("直接实例化耗时"+System.Environment.NewLine+stop.ElapsedMilliseconds);
stop.Reset();
stop.Start();
for (int i = 0; i < times; i++)
{
var per = Activator.CreateInstance(typeof(Person));
}
stop.Stop();
Console.WriteLine("Activator.CreateInstance(typeof(Person))实例化耗时" + System.Environment.NewLine + stop.ElapsedMilliseconds);
stop.Reset();
stop.Start();
for (int i = 0; i < times; i++)
{
var per = typeof(Person).GetConstructor(Type.EmptyTypes).Invoke(null);
}
stop.Stop();
Console.WriteLine("typeof(Person).GetConstructor(Type.EmptyTypes).Invoke(null)实例化耗时" + System.Environment.NewLine + stop.ElapsedMilliseconds);
stop.Reset();
stop.Start();
for (int i = 0; i < times; i++)
{
var per =Type.GetType("_Net的反射.Person").GetConstructor(Type.EmptyTypes).Invoke(null);
}
stop.Stop();
Console.WriteLine("Type.GetType(_Net的反射.Person).GetConstructor(Type.EmptyTypes).Invoke(null)实例化耗时" + System.Environment.NewLine + stop.ElapsedMilliseconds);
stop.Reset();
stop.Start();
for (int i = 0; i < times; i++)
{
var per = Activator.CreateInstance(Type.GetType("_Net的反射.Person"));
}
stop.Stop();
Console.WriteLine(" Activator.CreateInstance(Type.GetType(_Net的反射.Person))实例化耗时" + System.Environment.NewLine + stop.ElapsedMilliseconds);
stop.Reset();
//stop.Start();
//for (int i = 0; i < times; i++)
//{
// var per = System.Reflection.Assembly.Load("_Net的反射").CreateInstance("_Net的反射.Person");
//}
//stop.Stop();
//Console.WriteLine(" Assembly.Load(_Net的反射).CreateInstance(_Net的反射.Person)实例化耗时" + System.Environment.NewLine + stop.ElapsedMilliseconds);
//stop.Reset();
stop.Start();
var la=GetCreateFunc();
for (int i = 0; i < times; i++)
{
var per = la();
}
stop.Stop();
Console.WriteLine(" Func<Person> GetCreateFunc()实例化耗时" + System.Environment.NewLine + stop.ElapsedMilliseconds);
stop.Reset();
Console.ReadKey();
}
//表达式实例化对象
static Func<Person> GetCreateFunc() {
var newExpression = Expression.New(typeof(Person));
return Expression.Lambda<Func<Person>>(newExpression, null).Compile();
}
}
}
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