反射调用性能比较

来源：互联网发布：windows rt中文语言包编辑：程序博客网时间：2024/05/20 13:39

下面通过编写Demo的方式，验证各种反射的性能。

1、传统方式反射

           Type t = typeof(Person);
           MethodInfo methodInfo = t.GetMethod("Say");
           Person person = new Person();
           string word = "hello";
           Person p = null;
           object[] param = new object[] { word, p, 3 };
           int TestTimes = 1000000; //测试次数，可自行调节看效果

           #region 传统方式反射
           try
           {
               Stopwatch watch = new Stopwatch();
               watch.Start();
               for (int i = 0; i < TestTimes; i++)
               {
                   methodInfo.Invoke(person, param);
               }
               watch.Stop();
                Console.WriteLine(TestTimes.ToString() + " times invoked by Reflection: " + watch.ElapsedMilliseconds + "ms");
            }

            catch (System.Exception ex)
            {
                Console.WriteLine("传统方式反射直接错误:" + ex.Message);
                Console.WriteLine("传统方式反射内部错误:" + ex.InnerException.Message);
           }

#endregion2、实例化反射

#region 实例化反射

try
{

                Assembly Asm = Assembly.Load("testInvoke");//反射出空间
                Type type = Asm.GetType("testInvoke.Person");//反射出空间下的类
                object AssClas = Activator.CreateInstance(type);//动态实例化反射回来的指定空间下的指定类
                IPerson objPerson = (Person)AssClas; //转换为接口类型
                Stopwatch watch = new Stopwatch();
                watch.Start();
                for (int i = 0; i < TestTimes; i++)
                {
                    objPerson.Say(ref word, out p, 3);
                }
                watch.Stop();
                Console.WriteLine(TestTimes.ToString() + " times invoked by InstanceReflection@2: " + watch.ElapsedMilliseconds + "ms");
            }

            catch (System.Exception ex)
            {
                Console.WriteLine("实例化反射错误:" + ex.Message);
            }

#endregion3、快速反射

#region 快速反射

            try
            {
                Stopwatch watch1 = new Stopwatch();
                FastInvoke.FastInvokeHandler fastInvoker = FastInvoke.GetMethodInvoker(methodInfo);
                watch1.Start();
                for (int i = 0; i < TestTimes; i++)
                {
                    fastInvoker(person, param);
                }
                watch1.Stop();
                Console.WriteLine(TestTimes.ToString() + " times invoked by FastInvoke: " + watch1.ElapsedMilliseconds + "ms");
           }

           catch (System.Exception ex)
           {
               Console.WriteLine("快速反射错误:" + ex.Message);
           }

#endregion

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection.Emit;
using System.Reflection;

namespace testInvoke
{
     class FastInvoke
     {
         public delegate object FastInvokeHandler(object target, object[] paramters);
          static object InvokeMethod(FastInvokeHandler invoke, object target, params object[] paramters)
         {
             return invoke(null, paramters);
         }

public static FastInvokeHandler GetMethodInvoker(MethodInfo methodInfo)
{

             DynamicMethod dynamicMethod = new DynamicMethod(string.Empty, typeof(object), new Type[] { typeof(object), typeof(object[]) }, methodInfo.DeclaringType.Module);
            ILGenerator il = dynamicMethod.GetILGenerator();
            ParameterInfo[] ps = methodInfo.GetParameters();
            Type[] paramTypes = new Type[ps.Length];
            for (int i = 0; i < paramTypes.Length; i++)
            {
                if (ps[i].ParameterType.IsByRef)
                    paramTypes[i] = ps[i].ParameterType.GetElementType();
                else
                    paramTypes[i] = ps[i].ParameterType;

}

LocalBuilder[] locals = new LocalBuilder[paramTypes.Length];

             for (int i = 0; i < paramTypes.Length; i++)
             {
                 locals[i] = il.DeclareLocal(paramTypes[i], true);
             }

             for (int i = 0; i < paramTypes.Length; i++)
             {
                 il.Emit(OpCodes.Ldarg_1);
                 EmitFastInt(il, i);
                 il.Emit(OpCodes.Ldelem_Ref);
                 EmitCastToReference(il, paramTypes[i]);
                 il.Emit(OpCodes.Stloc, locals[i]);

}

             if (!methodInfo.IsStatic)
             {
                 il.Emit(OpCodes.Ldarg_0);
             }

             for (int i = 0; i < paramTypes.Length; i++)
             {
                 if (ps[i].ParameterType.IsByRef)
                     il.Emit(OpCodes.Ldloca_S, locals[i]);
                 else
                     il.Emit(OpCodes.Ldloc, locals[i]);

}

             if (methodInfo.IsStatic)
                il.EmitCall(OpCodes.Call, methodInfo, null);
            else
                il.EmitCall(OpCodes.Callvirt, methodInfo, null);

            if (methodInfo.ReturnType == typeof(void))
                il.Emit(OpCodes.Ldnull);
            else
                EmitBoxIfNeeded(il, methodInfo.ReturnType);

for (int i = 0; i < paramTypes.Length; i++)
{

                if (ps[i].ParameterType.IsByRef)
                {
                    il.Emit(OpCodes.Ldarg_1);
                    EmitFastInt(il, i);
                    il.Emit(OpCodes.Ldloc, locals[i]);
                    if (locals[i].LocalType.IsValueType)
                        il.Emit(OpCodes.Box, locals[i].LocalType);
                    il.Emit(OpCodes.Stelem_Ref);
                 }
             }

             il.Emit(OpCodes.Ret);
              FastInvokeHandler invoder = (FastInvokeHandler)dynamicMethod.CreateDelegate(typeof(FastInvokeHandler));
            return invoder;
        }

        private static void EmitCastToReference(ILGenerator il, System.Type type)
        {
            if (type.IsValueType)
            {
                il.Emit(OpCodes.Unbox_Any, type);
            }
            else
            {
                il.Emit(OpCodes.Castclass, type);
            }
        }
        private static void EmitBoxIfNeeded(ILGenerator il, System.Type type)
        {
            if (type.IsValueType)
            {
                il.Emit(OpCodes.Box, type);
            }
        }
        private static void EmitFastInt(ILGenerator il, int value)
        {

            switch (value)
            {
                case -1:

il.Emit(OpCodes.Ldc_I4_M1);

return;

case 0:

il.Emit(OpCodes.Ldc_I4_0);

return;

case 1:

il.Emit(OpCodes.Ldc_I4_1);

return;

case 2:

il.Emit(OpCodes.Ldc_I4_2);

return;

case 3:

il.Emit(OpCodes.Ldc_I4_3);

return;

case 4:

il.Emit(OpCodes.Ldc_I4_4);

return;

case 5:

il.Emit(OpCodes.Ldc_I4_5);

return;

case 6:

il.Emit(OpCodes.Ldc_I4_6);

return;

case 7:

il.Emit(OpCodes.Ldc_I4_7);

return;

case 8:

il.Emit(OpCodes.Ldc_I4_8);

return;
}

            if (value > -129 && value < 128)
            {
                il.Emit(OpCodes.Ldc_I4_S, (SByte)value);
            }
            else
            {
                il.Emit(OpCodes.Ldc_I4, value);
            }
        }
    }

}
4、不用反射，直接调用

#region 直接调用

         try
         {
             Stopwatch watch2 = new Stopwatch();
             watch2.Start();
             for (int i = 0; i < TestTimes; i++)
             {
                 person.Say(ref word, out p, 3);

                 }
                 watch2.Stop();
                 Console.WriteLine(TestTimes.ToString() + " times invoked by DirectCall: " + watch2.ElapsedMilliseconds + "ms");
            }
            catch (System.Exception ex)
            {
                Console.WriteLine("直接调用错误:" + ex.Message);
            }
            #endregion以上4种调用方式，100万次调用结果如下：

所以得出以下结论：

1. 不用反射，直接调用，效率最高。

2. 实例化反射，效率次之。

3. 快速反射，效率次之。

4. 传统反射，效率最差。

以上调用方式，后3种调用方式虽然效率有先后，但性能在一个数量级上，与传统反射相比，优越性较明显。

另外补充一点，实例化反射如果算上创建实例的性能损耗，试验结果如下图：

所以，如果需要频繁创建实例，建议不要采用实例化反射。