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
1 Type t = typeof(Person);
2 MethodInfo methodInfo = t.GetMethod("Say");
3 Person person = new Person();
4 string word = "hello";
5 Person p = null;
6 object[] param = new object[] { word, p, 3 };
7 int TestTimes = 1000000; //测试次数，可自行调节看效果
8
9 #region 传统方式反射
10 try
11 {
12 Stopwatch watch = new Stopwatch();
13 watch.Start();
14 for (int i = 0; i < TestTimes; i++)
15 {
16 methodInfo.Invoke(person, param);
17 }
18 watch.Stop();
19 Console.WriteLine(TestTimes.ToString() + " times invoked by Reflection: " + watch.ElapsedMilliseconds + "ms");
20 }
21 catch (System.Exception ex)
22 {
23 Console.WriteLine("传统方式反射 直接错误:" + ex.Message);
24 Console.WriteLine("传统方式反射 内部错误:" + ex.InnerException.Message);
25 }
26 #endregion
2、实例化反射
1 #region 实例化反射
2 try
3 {
4 //Stopwatch watch = new Stopwatch();
5 //watch.Start();
6 //for (int i = 0; i < TestTimes; i++)
7 //{
8 // Assembly Asm = Assembly.Load("testInvoke");//反射出空间
9 // Type type = Asm.GetType("testInvoke.Person");//反射出空间下的类
10 // object AssClas = Activator.CreateInstance(type);//动态实例化反射回来的指定空间下的指定类
11 // IPerson objPerson = (Person)AssClas; ////转换为接口类型
12 // objPerson.Say(ref word, out p, 3);
13 //}
14 //watch.Stop();
15 //Console.WriteLine(TestTimes.ToString() + " times invoked by InstanceReflection@1: " + watch.ElapsedMilliseconds + "ms");
16
17 Assembly Asm = Assembly.Load("testInvoke");//反射出空间
18 Type type = Asm.GetType("testInvoke.Person");//反射出空间下的类
19 object AssClas = Activator.CreateInstance(type);//动态实例化反射回来的指定空间下的指定类
20 IPerson objPerson = (Person)AssClas; //转换为接口类型
21 Stopwatch watch = new Stopwatch();
22 watch.Start();
23 for (int i = 0; i < TestTimes; i++)
24 {
25 objPerson.Say(ref word, out p, 3);
26 }
27 watch.Stop();
28 Console.WriteLine(TestTimes.ToString() + " times invoked by InstanceReflection@2: " + watch.ElapsedMilliseconds + "ms");
29
30 }
31 catch (System.Exception ex)
32 {
33 Console.WriteLine("实例化反射 错误:" + ex.Message);
34 }
35 #endregion
3、快速反射
1 #region 快速反射
2 try
3 {
4 Stopwatch watch1 = new Stopwatch();
5 FastInvoke.FastInvokeHandler fastInvoker = FastInvoke.GetMethodInvoker(methodInfo);
6 watch1.Start();
7 for (int i = 0; i < TestTimes; i++)
8 {
9 fastInvoker(person, param);
10 }
11 watch1.Stop();
12 Console.WriteLine(TestTimes.ToString() + " times invoked by FastInvoke: " + watch1.ElapsedMilliseconds + "ms");
13 }
14 catch (System.Exception ex)
15 {
16 Console.WriteLine("快速反射 错误:" + ex.Message);
17 }
18 #endregion
1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Text;
5 using System.Reflection.Emit;
6 using System.Reflection;
7
8 namespace testInvoke
9 {
10 class FastInvoke
11 {
12 public delegate object FastInvokeHandler(object target, object[] paramters);
13
14 static object InvokeMethod(FastInvokeHandler invoke, object target, params object[] paramters)
15 {
16 return invoke(null, paramters);
17 }
18
19 public static FastInvokeHandler GetMethodInvoker(MethodInfo methodInfo)
20 {
21 DynamicMethod dynamicMethod = new DynamicMethod(string.Empty, typeof(object), new Type[] { typeof(object), typeof(object[]) }, methodInfo.DeclaringType.Module);
22 ILGenerator il = dynamicMethod.GetILGenerator();
23 ParameterInfo[] ps = methodInfo.GetParameters();
24 Type[] paramTypes = new Type[ps.Length];
25 for (int i = 0; i < paramTypes.Length; i++)
26 {
27 if (ps[i].ParameterType.IsByRef)
28 paramTypes[i] = ps[i].ParameterType.GetElementType();
29 else
30 paramTypes[i] = ps[i].ParameterType;
31 }
32 LocalBuilder[] locals = new LocalBuilder[paramTypes.Length];
33
34 for (int i = 0; i < paramTypes.Length; i++)
35 {
36 locals[i] = il.DeclareLocal(paramTypes[i], true);
37 }
38 for (int i = 0; i < paramTypes.Length; i++)
39 {
40 il.Emit(OpCodes.Ldarg_1);
41 EmitFastInt(il, i);
42 il.Emit(OpCodes.Ldelem_Ref);
43 EmitCastToReference(il, paramTypes[i]);
44 il.Emit(OpCodes.Stloc, locals[i]);
45 }
46 if (!methodInfo.IsStatic)
47 {
48 il.Emit(OpCodes.Ldarg_0);
49 }
50 for (int i = 0; i < paramTypes.Length; i++)
51 {
52 if (ps[i].ParameterType.IsByRef)
53 il.Emit(OpCodes.Ldloca_S, locals[i]);
54 else
55 il.Emit(OpCodes.Ldloc, locals[i]);
56 }
57 if (methodInfo.IsStatic)
58 il.EmitCall(OpCodes.Call, methodInfo, null);
59 else
60 il.EmitCall(OpCodes.Callvirt, methodInfo, null);
61 if (methodInfo.ReturnType == typeof(void))
62 il.Emit(OpCodes.Ldnull);
63 else
64 EmitBoxIfNeeded(il, methodInfo.ReturnType);
65
66 for (int i = 0; i < paramTypes.Length; i++)
67 {
68 if (ps[i].ParameterType.IsByRef)
69 {
70 il.Emit(OpCodes.Ldarg_1);
71 EmitFastInt(il, i);
72 il.Emit(OpCodes.Ldloc, locals[i]);
73 if (locals[i].LocalType.IsValueType)
74 il.Emit(OpCodes.Box, locals[i].LocalType);
75 il.Emit(OpCodes.Stelem_Ref);
76 }
77 }
78
79 il.Emit(OpCodes.Ret);
80 FastInvokeHandler invoder = (FastInvokeHandler)dynamicMethod.CreateDelegate(typeof(FastInvokeHandler));
81 return invoder;
82 }
83
84 private static void EmitCastToReference(ILGenerator il, System.Type type)
85 {
86 if (type.IsValueType)
87 {
88 il.Emit(OpCodes.Unbox_Any, type);
89 }
90 else
91 {
92 il.Emit(OpCodes.Castclass, type);
93 }
94 }
95
96 private static void EmitBoxIfNeeded(ILGenerator il, System.Type type)
97 {
98 if (type.IsValueType)
99 {
100 il.Emit(OpCodes.Box, type);
101 }
102 }
103
104 private static void EmitFastInt(ILGenerator il, int value)
105 {
106 switch (value)
107 {
108 case -1:
109 il.Emit(OpCodes.Ldc_I4_M1);
110 return;
111 case 0:
112 il.Emit(OpCodes.Ldc_I4_0);
113 return;
114 case 1:
115 il.Emit(OpCodes.Ldc_I4_1);
116 return;
117 case 2:
118 il.Emit(OpCodes.Ldc_I4_2);
119 return;
120 case 3:
121 il.Emit(OpCodes.Ldc_I4_3);
122 return;
123 case 4:
124 il.Emit(OpCodes.Ldc_I4_4);
125 return;
126 case 5:
127 il.Emit(OpCodes.Ldc_I4_5);
128 return;
129 case 6:
130 il.Emit(OpCodes.Ldc_I4_6);
131 return;
132 case 7:
133 il.Emit(OpCodes.Ldc_I4_7);
134 return;
135 case 8:
136 il.Emit(OpCodes.Ldc_I4_8);
137 return;
138 }
139
140 if (value > -129 && value < 128)
141 {
142 il.Emit(OpCodes.Ldc_I4_S, (SByte)value);
143 }
144 else
145 {
146 il.Emit(OpCodes.Ldc_I4, value);
147 }
148 }
149 }
150 }
4、不用反射，直接调用
1 #region 直接调用
2 try
3 {
4 Stopwatch watch2 = new Stopwatch();
5 watch2.Start();
6 for (int i = 0; i < TestTimes; i++)
7 {
8 person.Say(ref word, out p, 3);
9 }
10 watch2.Stop();
11 Console.WriteLine(TestTimes.ToString() + " times invoked by DirectCall: " + watch2.ElapsedMilliseconds + "ms");
12 }
13 catch (System.Exception ex)
14 {
15 Console.WriteLine("直接调用 错误:" + ex.Message);
16 }
17 #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。
源码下载：files.cnblogs.com/tianzhiliang/testInvoke.rar
抄自：http://www.cnblogs.com/tianzhiliang/archive/2012/06/29/2570275.html