.NET Core利用动态代理实现AOP(面向切面编程)_实用技巧_

class Program { static void Main(string[] args) { Console.WriteLine("Hello World!"); } }

IL_0000: nop IL_0001: ldstr "Hello World!" IL_0006: call void [System.Console]System.Console::WriteLine(string) IL_000b: nop IL_000c: ret

internal class DynamicProxy : DispatchProxy { public T? decorated { get; set; }//目标类 public Action? _afterAction { get; set; } // 动作之后执行 public Action? _beforeAction { get; set; } // 动作之前执行 protected override object? Invoke(MethodInfo? targetMethod, object?[]? args) { Exception exception = null; AfterAction(args); object result = null; try { //调用实际目标对象的方法 result = targetMethod?.Invoke(decorated, args); } catch (Exception ex) { exception = ex; } BeforeAction(args, result); //调用完执行方法后的委托，如果有异常，抛出异常 if (exception != null) { throw exception; } return result; } /// 
 /// 创建代理实例 /// 
 /// 代理的接口类型 /// 方法执行前执行的事件 /// 方法执行后执行的事件 ///  public T Create(T decorated, Action afterAction, Action beforeAction) { object proxy = Create>(); // 调用DispatchProxy 的Create 创建一个新的T DynamicProxy proxyDecorator = (DynamicProxy)proxy; proxyDecorator.decorated = decorated; //把自定义的方法委托给代理类 proxyDecorator._afterAction = afterAction; proxyDecorator._beforeAction = beforeAction; return (T)proxy; } private void AfterAction(object?[]? args) { try { _afterAction.Invoke(args); } catch (Exception ex) { Console.WriteLine($"执行之前异常：{ex.Message}，{ex.StackTrace}"); } } private void BeforeAction(object?[]? args, object? result) { try { _beforeAction.Invoke(args, result); } catch (Exception ex) { Console.WriteLine($"执行之后异常：{ex.Message}，{ex.StackTrace}"); } } }

internal interface IInterceptor { /// 
 /// 执行之前 /// 
 /// 参数 void AfterAction(object?[]? args); /// 
 /// 执行之后 /// 
 /// 参数 /// 结果 void BeforeAction(object?[]? args, object result); }

[AttributeUsage(AttributeTargets.Class)] internal class InterceptAttribut : Attribute { public Type Type { get; set; } public InterceptAttribut(Type type) { this.Type = type; } }

internal class ProxyFactory { /// 
 /// 创建代理实例 /// 
 /// 代理的接口类型 ///  public static T Create() { var decorated = ServiceHelp.GetService(); var type = decorated.GetType(); var interceptAttribut = type.GetCustomAttribute(); var interceptor = ServiceHelp.GetService(interceptAttribut.Type); //创建代理类 var proxy = new DynamicProxy().Create(decorated, interceptor.AfterAction, interceptor.BeforeAction); return proxy; } }

public static class ServiceHelp { public static IServiceProvider? serviceProvider { get; set; } public static void BuildServiceProvider(IServiceCollection serviceCollection) { //构建容器 serviceProvider = serviceCollection.BuildServiceProvider(); } public static T GetService(Type serviceType) { return (T)serviceProvider.GetService(serviceType); } public static T GetService() { return serviceProvider.GetService(); } }

 internal class AOPTest : IInterceptor { public void AfterAction(object?[]? args) { Console.WriteLine($"AOP方法执行之前，args：{args}"); throw new Exception("异常测试（异常，但依然不能影响程序执行）"); } public void BeforeAction(object?[]? args, object result) { Console.WriteLine($"AOP方法执行之后，args：{args}，result：{result}"); } }

 internal interface ITestService { public int Add(int a, int b); }

 [InterceptAttribut(typeof(AOPTest))] internal class TestService : ITestService { public int Add(int a, int b) { Console.WriteLine($"正在执行--》Add({a},{b})"); throw new Exception("方法执行--》测试异常"); return a + b; } }

// See https://aka.ms/new-console-template for more information using Infrastructure.DynamicProxy; using Microsoft.Extensions.DependencyInjection; Console.WriteLine("Hello, World!"); //容器注册 IServiceCollection serviceCollection = new ServiceCollection(); serviceCollection.AddTransient(typeof(AOPTest)); serviceCollection.AddTransient(); //构建容器 ServiceHelp.BuildServiceProvider(serviceCollection); //用工厂获取代理实例 var s = ProxyFactory.Create(); var sum = s.Add(1, 2); Console.WriteLine("执行完毕=====>" + sum);