推荐订阅源

class Student
{            
    public string Name { get; set; }
}static double Test(int loop, Student stu, Func<Student, string> action)
{
    var watch = Stopwatch.StartNew();
    string s = null;
    for (var i = 0; i < loop; i++)
        s = action(stu);return watch.ElapsedTicks;
}static Func<Student, string> NativeGetter()
{
    return s => s.Name;
}static Func<Student, string> ReflectedGetter()
{
    var type = typeof (Student);
    var prop = type.GetProperty("Name");return s => (string)prop.GetValue(s, null);                       
}static Func<Student, string> EmittedGetter()
{
    var dm = new DynamicMethod(name: "EmittedGetter", returnType: typeof(string), parameterTypes: new[] { typeof(Student) }, owner: typeof(Student));
    var type 
= typeof (Student);
    var prop = type.GetMethod("get_Name");
    var il = dm.GetILGenerator();
    il.Emit(OpCodes.Ldarg_0);
    il.Emit(OpCodes.Call, prop);
    il.Emit(OpCodes.Ret);return (Func<Student, string>)dm.CreateDelegate(typeof(Func<Student, string>));
}static Func<Student, string> ExpressionGetter()
{
    var type = typeof(Student);
    var prop = type.GetMethod("get_Name");
    ParameterExpression pa = Expression.Parameter(typeof(Student));
    Expression body = Expression.Call(pa, prop);return Expression.Lambda<Func<Student, string>>(body, pa).Compile();
}static Func<Student, string> DynamicGetter()
{
    return s => { dynamic d = s; return d.Name; };
}
[MethodImpl(MethodImplOptions.NoOptimization)]public static void Run()
{
    const int loop = 5000000;
    var stu = new Student {Name = "Mike"};
    var dynamic =
        Test(loop, stu, DynamicGetter());
    var expression =
        Test(loop, stu, ExpressionGetter());
    var native = 
        Test(loop, stu, NativeGetter());
    var emitted =
        Test(loop, stu, EmittedGetter());                        
                var reflected =
        Test(loop, stu, ReflectedGetter());           
    Console.WriteLine("native:{0}\ndynamic:{1}\nemit:{2}\nexpression:{3}\nreflection:{4}", 1, dynamic / native, emitted / native, expression / native, reflected / native);
    Console.ReadKey();
}

测试结果

1. 当循环次数比较小的时候， loop=1000

native:1
dynamic:540.444964871194
emit:0.704918032786885
expression:0.224824355971897
reflection:8.37002341920375

2. loop=5000000

native:1
dynamic:4.37328053807767
emit:0.96159470600998
expression:1.00412887828162
reflection:35.909097418095