public void SaveData(InputClass input)
{Stopwatch timer= new Stopwatch();timer.Start();logger.Info("enterd SaveData method");if(logger.LogLevel==LoggingLeve.Debug){logger.Debug(MyJsonTool.ConvertToJson(input);}dataRepositoryInstance.Save(input);timer.End();logger.Info($"enterd SaveData method in {timer.ElapsedMilliseconds}ms");
}

如果我告诉你所有这些代码仅通过编写就可以产生相同的输出怎么办？

public virtual void SaveData(InputClass input)
{dataRepositoryInstance.Save(input);
}

因此，所有工作都只需在方法中添加一个virtual关键字，那太好了！稍后我们将返回virtual关键字，以了解它与AOP的关系。

[Fetch("SELECT * FROM customers WHERE name=?")]
public List<MyDTO> GetByName(string name)
{return new List<MyDTO>();
}

我希望您现在已经确信AOP可以在许多情况下提供帮助并且可以成为强大的盟友。让我们看看它是如何工作的以及如何将其集成到.NET Core应用程序中。

public class AutofacModule : Module{protected override void Load(ContainerBuilder builder){// Register the interceptorbuilder.Register(c => new CallLogger()).Named<IInterceptor>("log-calls");builder.Register(c => new ValuesService(c.Resolve<ILogger<ValuesService>>())).As<IValuesService>().InstancePerLifetimeScope()                .EnableInterfaceInterceptors();}}  public class CallLogger : IInterceptor{public void Intercept(IInvocation invocation){var executionId = Guid.NewGuid().ToString();Debug.WriteLine("{0} - Calling method {1} with parameters {2}... ", executionId,invocation.Method.Name,JsonConvert.SerializeObject(invocation.Arguments));invocation.Proceed();Debug.WriteLine("{0} - Done: result was {1}.", executionId, JsonConvert.SerializeObject( invocation.ReturnValue));}}

我们可以讨论直到明天为止的愚蠢行为，例如如何将数据愚蠢地转储到日志中，或者我们可以改进该系统以使用更好的日志记录系统，以及一种巧妙的方式来跟踪输入，时序和输出。

public interface IFruitRepository
{[Query("SELECT * FROM fruits where family={0}")]List<Fruit> GetFruits(string tree);[Query("SELECT * FROM fruits where family='Citrus'")]List<Fruit> GetCitrus(string tree);public void InitDB();
}public  class FruitRepositoryImpl{public void InitDB(){using (var db = new FruitDB()){db.Database.EnsureCreated();var count = db.Fruits.Count();if (count == 0){db.Fruits.Add(new Fruit(){Name = "Lemon",Family = "Citrus"});//... all the fruit of the world heredb.SaveChanges();}}}}

步骤2：代理

public class ProxyFacotory<T> : DispatchProxy
{private T _decorated;protected override object Invoke(MethodInfo targetMethod, object[] args){        //Find an annotation on the interfacevar annotations = targetMethod.GetCustomAttributes(true);var aopAttr = annotations.FirstOrDefault(x => typeof(AOPAttribute).IsAssignableFrom(x.GetType())) as AOPAttribute;//in case the method has an AOP implementation, this is executedif (aopAttr != null){return aopAttr.Execute(targetMethod, args, annotations);}//otherwise, the manual implementation on class is triggeredvar inherithedMethod=interfaceMethods.FirstOrDefault(x => x.Name == targetMethod.Name);var result = inherithedMethod.Invoke(_decorated, args);return result;}public static T Create<T,TProxy>(TProxy instance) where T : class where TProxy:class{object proxy = Create<T, ProxyFacotory<TProxy>>();((ProxyFacotory<TProxy>)proxy).SetParameters(instance);return (T)proxy;}private void SetParameters(T decorated){_decorated = decorated;}
}

用法非常简单，并使用常规的.NET Core依赖项注入。

//the proxy instance return an instance based on the concrete implementation
var instance=ProxyFacotory<IFruitRepository>.Create<IFruitRepository,FruitRepositoryImpl>(new FruitRepositoryImpl());
var serviceProvider = new ServiceCollection().AddSingleton<IFruitRepository>(instance).BuildServiceProvider();

步骤3：注释(Annotation)

public abstract class AOPAttribute: Attribute{public abstract object Execute(MethodInfo targetMethod, object[] args, object[] annotations);}public class QueryAttribute : AOPAttribute{public string Template { get; set; }public   QueryAttribute(string template){this.Template = template;}public override object Execute(MethodInfo targetMethod, object[] args, object[] annotations){using (var data = new FruitDB()){return data.Fruits.FromSqlRaw<Fruit>(this.Template,args ).ToList(); //Dataset can be //taken by target field}}}

步骤4：实际操作

var fruitRepository = serviceProvider.GetService<IFruitRepository>();
//This calls the manual method and fill the database
fruitRepository.InitDB();
//This uses a dynamic definition
var fruits=fruitRepository.GetFruits("Citrus");

带什么回家