用C#写一个特性，在函数上面可以自动计算函数耗时情况

TimingAttribute类是自定义的特性类，用来标记需要计时的方法。TimingInterceptor类是一个拦截器，它通过反射来拦截被TimingAttribute标记的方法，并在方法执行前后进行计时。MyClass中的MyMethod方法被标记为需要计时，当调用这个方法时，它会被TimingInterceptor拦截，计算执行时间并输出。

using System;
using System.Diagnostics;
using System.Reflection;[AttributeUsage(AttributeTargets.Method)]
public class TimingAttribute : Attribute
{public void OnEntry(){Console.WriteLine("Method execution started.");}public void OnExit(double milliseconds){Console.WriteLine($"Method execution finished. Elapsed time: {milliseconds} milliseconds");}
}public class TimingInterceptor
{public void Intercept(MethodInfo targetMethod){var timingAttribute = (TimingAttribute)targetMethod.GetCustomAttribute(typeof(TimingAttribute));if (timingAttribute != null){timingAttribute.OnEntry();var stopwatch = Stopwatch.StartNew();targetMethod.Invoke(null, null);stopwatch.Stop();timingAttribute.OnExit(stopwatch.Elapsed.TotalMilliseconds);}else{targetMethod.Invoke(null, null);}}
}public class MyClass
{[Timing]public static void MyMethod(){// 模拟一个耗时的操作System.Threading.Thread.Sleep(2000);Console.WriteLine("MyMethod executed.");}
}class Program
{static void Main(string[] args){TimingInterceptor interceptor = new TimingInterceptor();MethodInfo method = typeof(MyClass).GetMethod("MyMethod");interceptor.Intercept(method);}
}