c# 为实体赋值通过直接赋值，Emit，反射三种方法测试

 public class Class1
    {
        public static void Button_Click()
        {
            TestDemoEntity entity;
            Stopwatch watch;
            int length = 1000000;

            #region 直接赋值    1
            watch = new Stopwatch();
            watch.Start();
            entity = new TestDemoEntity();
            for (int i = 0; i < length; i++)
            {
                entity.Name = "测试";
            }
            watch.Start();
            Console.WriteLine("直接赋值:" + watch.ElapsedMilliseconds);
            #endregion

            #region 通过Emit赋值    2
            watch = new Stopwatch();
            watch.Start();
            entity = new TestDemoEntity();
            var emitSetter = EmitSetter<TestDemoEntity>("Name");
            for (int i = 0; i < length; i++)
            {
                emitSetter(entity, "测试" + i);
            }
            watch.Start();
            Console.WriteLine("通过Emit赋值:" + watch.ElapsedMilliseconds);

            #endregion

            #region 通过反射赋值  3
            watch = new Stopwatch();
            watch.Start();
            entity = new TestDemoEntity();
            for (int i = 0; i < length; i++)
            {
                ReflectSetter(entity, "Name", "测试");
            }
            watch.Start();
            Console.WriteLine("通过反射赋值:" + watch.ElapsedMilliseconds);

            #endregion
        }

        public static Action<T, object> EmitSetter<T>(string propertyName)
        {
            var type = typeof(T);
            var dynamicMethod = new DynamicMethod("EmitCallable", null, new[] { type, typeof(object) }, type.Module);//定义和表示一个可以编译，执行和丢弃的动态方法
            var iLGenerator = dynamicMethod.GetILGenerator();//返回方法的Microsoft中间语言（MSIL）生成器，默认的MSIL流大小为64字节
            if (iLGenerator != null)
            {
                var callMethod = type.GetMethod("set_" + propertyName, BindingFlags.Instance | BindingFlags.IgnoreCase | BindingFlags.Public);//获取字段set属性
                if (callMethod != null)
                {
                    var parameterInfo = callMethod.GetParameters()[0];
                    if (parameterInfo != null)
                    {
                        var local = iLGenerator.DeclareLocal(parameterInfo.ParameterType, true);
                        #region Emit()将指定的指令放在指令流上，该方法接收一个IL流。EmitCall()将 call 或 callvirt 指令置于 Microsoft 中间语言 (MSIL) 流，以调用varargs 方法。我们看到OpCodes类，该类描述中间语言 (IL) 指令
                        iLGenerator.Emit(OpCodes.Ldarg_1);
                        if (parameterInfo.ParameterType.IsValueType)
                        {
                            // 如果是值类型，拆箱
                            iLGenerator.Emit(OpCodes.Unbox_Any, parameterInfo.ParameterType);
                        }
                        else
                        {
                            // 如果是引用类型，转换
                            iLGenerator.Emit(OpCodes.Castclass, parameterInfo.ParameterType);
                        }
                        iLGenerator.Emit(OpCodes.Stloc, local);//OpCodes类，该类描述中间语言 (IL) 指令
                        iLGenerator.Emit(OpCodes.Ldarg_0);//将指定的指令放在指令流上，该方法接收一个IL流
                        iLGenerator.Emit(OpCodes.Ldloc, local);
                        iLGenerator.EmitCall(OpCodes.Callvirt, callMethod, null);//将 call 或 callvirt 指令置于 Microsoft 中间语言 (MSIL) 流，以调用varargs 方法
                        iLGenerator.Emit(OpCodes.Ret); 
                        #endregion
                    }
                }
            }
            return dynamicMethod.CreateDelegate(typeof(Action<T, object>)) as Action<T, object>;//CreateDelegate()完成动态方法并创建一个可用于执行它的委托。
        }
        public static void ReflectSetter(object obj, string propertyName, object propertyValue)
        {
            var type = obj.GetType();
            var propertyInfo = type.GetProperty(propertyName);
            propertyInfo.SetValue(obj, propertyValue, null);
        }
    }
    public class TestDemoEntity
    {
        public string Name { get; set; }
    }