利用不同方法创建类的性能比较

在设计和实现中，很多地方都用到reflection。用Reflection创建类会在一定程度上造成性能上的损失。但损失有多大？前些日子写了个程序用不同的方法创建类的实例，测试结果如下：

方法/创建次数	1000	10000	100000	1000000
new 操作符	0	5	45	472
delegate	3	25	241	2811
Reflection	9	92	890	9615
友元函数	17	148	1492	16091

可以看到用new操作符创建类比用Reflection快将近20倍之多。测试代码如下：

using System;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Diagnostics;

namespace ReflectionTest
{
    public interface ISmartObj
    {
        object CreateInstance();
    }

    class TestClass : ISmartObj
    {
        static int start = 0;
        public TestClass()
        {
             x = start++;
        }
        public static TestClass Create()
        {
            return new TestClass();
        }

        public int x;
        ISmartObj Members#region ISmartObj Members

        public object CreateInstance()
        {
            return new TestClass();
        }

        #endregion
    }

    class ReflectClass
    {
        private static Type[] memNoTypes = new Type[0];
        private static object[] memNoPara = new object[0];
        private static int memMaxTimes = 1000000;
        private delegate TestClass CreateSmartObject();

        [DllImport("kernel32.dll")]
        private static extern bool QueryPerformanceCounter(out long lpPerformanceCount);

        [DllImport("Kernel32.dll")]
        private static extern bool QueryPerformanceFrequency(out long lpFrequency);

        private static long UseNew(ISmartObj paraInterface)
        {
            object o;
            long tempStart, tempEnd;
            int i;
            QueryPerformanceCounter(out tempStart);
            for (i=0;i<memMaxTimes;i++)
                o = paraInterface.CreateInstance();
            QueryPerformanceCounter(out tempEnd);
            return tempEnd - tempStart;
        }

        private static long UseRefection(Type paraType)
        {
            object o;
            int i;
            long tempStart, tempEnd;
            QueryPerformanceCounter(out tempStart);
            for (i=0;i<memMaxTimes;i++)
                o = (TestClass)Activator.CreateInstance(paraType, false);
            QueryPerformanceCounter(out tempEnd);
            return tempEnd - tempStart;
        }

        private static long UseMethod(MethodInfo paraInfo)
        {
            object o;
            int i;
            long tempStart, tempEnd;
            QueryPerformanceCounter(out tempStart);
            for (i=0;i<memMaxTimes;i++)
                o = paraInfo.Invoke(null,memNoPara);
            QueryPerformanceCounter(out tempEnd);
            return tempEnd - tempStart;
        }

        private static long UseDelegate(Delegate paraDelegate)
        {
            object o;
            long tempStart, tempEnd;
            int i;
            QueryPerformanceCounter(out tempStart);
            for (i=0;i<memMaxTimes;i++)
                o = (TestClass)paraDelegate.DynamicInvoke(memNoPara);
            QueryPerformanceCounter(out tempEnd);
            return tempEnd - tempStart;
        }

        [STAThread]
        static void Main(string[] args)
        {
            Type tempType = typeof(TestClass);
            ISmartObj tempInterface = (ISmartObj)(new TestClass());
            MethodInfo tempInfo = tempType.GetMethod("Create",memNoTypes);
            Delegate tempDelegate= Delegate.CreateDelegate(typeof(CreateSmartObject), tempInfo);
            long tempFreq, tempCost;

            QueryPerformanceFrequency(out tempFreq);

            tempCost = UseNew(tempInterface);
            Console.WriteLine("UseNew:{0}",tempCost *1000/tempFreq);

            tempCost = UseDelegate(tempDelegate);
            Console.WriteLine("UseDel:{0}",tempCost *1000/tempFreq);

            tempCost = UseRefection(tempType);
            Console.WriteLine("UseRef:{0}",tempCost *1000/tempFreq);

            tempCost = UseMethod(tempInfo);
            Console.WriteLine("UseFun:{0}",tempCost *1000/tempFreq);

        }
    }
}