【转】替代反射调用的几种方式及性能测试 - 51Testing软件测试论坛

public class MyMath
{
public int Add(int a, int b)
{
return a + b;
}
}

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dynamic math = new MyMath();
int result = math.Add(1, 2);

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var math = new MyMath();
Expression<Func<int, int, int>> add = (a, b) => math.Add(a, b);

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var add = typeof(MyMath).GetMethod("Add");
var math = Expression.Parameter(typeof(MyMath));
var a = Expression.Parameter(typeof(int), "a");
var b = Expression.Parameter(typeof(int), "b");
var body = Expression.Call(myMath, add, a, b);
var lambda = Expression.Lambda<Func<MyMath, int, int, int>>(body, math, a, b);

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var math = new MyMath();
Expression<Func<int, int, int>> addExpTree = (a, b) => math.Add(a, b); // ExressionTree
Func<int, int, int> add = addExpTree.Compile(); // 编译成委托
var result = add(1, 2); // 相加，结果为3

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var addMethod = typeof(MyMath).GetMethod("Add");
var dynamicMethod = new DynamicMethod("", typeof(int), new[] { typeof(MyMath), typeof(int), typeof(int) });
//
var il = dynamicMethod.GetILGenerator();
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ldarg_1);
il.Emit(OpCodes.Ldarg_2);
il.Emit(OpCodes.Callvirt, addMethod);
il.Emit(OpCodes.Ret);
//
var add = (Func<MyMath, int, int, int>)dynamicMethod.CreateDelegate(typeof(Func<MyMath, int, int, int>));
//
var math = new MyMath();
var result = add(math, 1, 2);

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using System;
using System.Linq.Expressions;
using System.Reflection.Emit;
public class MyMath {
public int Add(int a, int b) { return a + b; }
}
class Program {
static void Main(string[] args) {
int result;
var math = new MyMath();
var count = 1000000;
Console.WriteLine("数据量：" + count);
Console.WriteLine("-----------------------------r\n");
using (Profiler.Step("循环：{0} ms")) {
for (int i = 0; i < count; i++)
result = 1;
}
using (Profiler.Step("直接调用：{0} ms")) {
for (int i = 0; i < count; i++)
result = math.Add(i, i);
}
using (Profiler.Step("反射发出：{0} ms")) {
var emitAdd = BuildEmitAddFunc();
for (int i = 0; i < count; i++)
result = emitAdd(math, i, i);
}
using (Profiler.Step("表达式树：{0} ms")) {
var expressionAdd = BuildExpressionAddFunc();
for (int i = 0; i < count; i++)
result = expressionAdd(math, i, i);
}
using (Profiler.Step("dynamic 调用：{0} ms")) {
dynamic d = math;
for (int i = 0; i < count; i++)
result = d.Add(i, i);
}
using (Profiler.Step("反射调用：{0} ms")) {
var add = typeof(MyMath).GetMethod("Add");
for (int i = 0; i < count; i++)
result = (int)add.Invoke(math, new object[] { i, i });
}
Console.WriteLine("\r\n\r\n测试完成，任意键退出...");
Console.ReadKey();
}
static Func<MyMath, int, int, int> BuildExpressionAddFunc() {
var add = typeof(MyMath).GetMethod("Add");
var math = Expression.Parameter(typeof(MyMath));
var a = Expression.Parameter(typeof(int), "a");
var b = Expression.Parameter(typeof(int), "b");
var body = Expression.Call(math, add, a, b);
var lambda = Expression.Lambda<Func<MyMath, int, int, int>>(body, math, a, b);
return lambda.Compile();
}
static Func<MyMath, int, int, int> BuildEmitAddFunc() {
var add = typeof(MyMath).GetMethod("Add");
var dynamicMethod = new DynamicMethod("", typeof(int), new[] { typeof(MyMath), typeof(int), typeof(int) });
var il = dynamicMethod.GetILGenerator();
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ldarg_1);
il.Emit(OpCodes.Ldarg_2);
il.Emit(OpCodes.Callvirt, add);
il.Emit(OpCodes.Ret);
return (Func<MyMath, int, int, int>)dynamicMethod.CreateDelegate(typeof(Func<MyMath, int, int, int>));
}
}

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using System;
using System.Diagnostics;
public class Profiler : IDisposable {
private Stopwatch watch;
private string message;
private Profiler(string message) {
this.watch = new Stopwatch();
this.watch.Start();
this.message = message;
}
public void Dispose() {
watch.Stop();
Console.WriteLine(message, watch.ElapsedMilliseconds);
Console.WriteLine();
}
public static IDisposable Step(string message) {
return new Profiler(message);
}
public static T Inline<T>(string message, Func<T> func) {
using (new Profiler(message))
return func();
}
}

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