（八）React Ant Design Pro + .Net5 WebApi：后端环境搭建Aop

一、Aop

Aop 面向切面编程(Aspect Oriented Program），在项目中，很多地方都会用到Aop的概念，比如：过滤器(Filter)，中间件(Middleware) 通常用来处理数据请求、切面缓存、记录日志、异常捕获等等。但是想在服务层中使用Aop，前面说的就不好使了，目的是减少代码入侵，降低解耦，又能实现业务需求，才是Aop意义所在。前面介绍使用了Autofac，在这还能发挥作用。

1、安装

安装Autofac.Extras.DynamicProxy，Autofac实现Aop用的是Castle.Core动态代理，Castle.Core可以单独使用，跟Autofac配合起来更方便。Autofac.Extras.DynamicProxy依赖Autofac，所以有的文章是直接就装了这个包，一个效果。

2、异步处理

Castle.Core本身是不支持异步的，所以参考封装异步Aop类 AsyncInterceptorBase 继承 IInterceptor。

public abstract class AsyncInterceptorBase : IInterceptor
{
    public AsyncInterceptorBase()
    {
    }

    public void Intercept(IInvocation invocation)
    {
        BeforeProceed(invocation);
        invocation.Proceed();
        if (IsAsyncMethod(invocation.MethodInvocationTarget))
        {
            InterceptAsync((dynamic)invocation.ReturnValue, invocation);
        }
        else
        {
            AfterProceedSync(invocation);
        }
    }

    private bool CheckMethodReturnTypeIsTaskType(MethodInfo method)
    {
        var methodReturnType = method.ReturnType;
        if (methodReturnType.IsGenericType)
        {
            if (methodReturnType.GetGenericTypeDefinition() == typeof(Task<>) ||
                methodReturnType.GetGenericTypeDefinition() == typeof(ValueTask<>))
                return true;
        }
        else
        {
            if (methodReturnType == typeof(Task) ||
                methodReturnType == typeof(ValueTask))
                return true;
        }
        return false;
    }

    private bool IsAsyncMethod(MethodInfo method)
    {
        bool isDefAsync = Attribute.IsDefined(method, typeof(AsyncStateMachineAttribute), false);
        bool isTaskType = CheckMethodReturnTypeIsTaskType(method);
        bool isAsync = isDefAsync && isTaskType;

        return isAsync;
    }

    private async Task InterceptAsync(Task task, IInvocation invocation)
    {
        await task.ConfigureAwait(false);
        AfterProceedAsync(invocation, false);
    }

    private async Task<TResult> InterceptAsync<TResult>(Task<TResult> task, IInvocation invocation)
    {
        TResult ProceedAsyncResult = await task.ConfigureAwait(false);
        invocation.ReturnValue = ProceedAsyncResult;
        AfterProceedAsync(invocation, true);
        return ProceedAsyncResult;
    }

    private async ValueTask InterceptAsync(ValueTask task, IInvocation invocation)
    {
        await task.ConfigureAwait(false);
        AfterProceedAsync(invocation, false);
    }

    private async ValueTask<TResult> InterceptAsync<TResult>(ValueTask<TResult> task, IInvocation invocation)
    {
        TResult ProceedAsyncResult = await task.ConfigureAwait(false);
        invocation.ReturnValue = ProceedAsyncResult;
        AfterProceedAsync(invocation, true);
        return ProceedAsyncResult;
    }

    protected virtual void BeforeProceed(IInvocation invocation) { }
    protected virtual void AfterProceedSync(IInvocation invocation) { }
    protected virtual void AfterProceedAsync(IInvocation invocation, bool hasAsynResult) { }
}

新建一个服务切面类 ServiceAop 继承 AsyncInterceptorBase

public class ServiceAop : AsyncInterceptorBase
{
    private readonly ILogger<ServiceAop> _logger;
    public ServiceAop(ILogger<ServiceAop> logger) {
        _logger = logger;
    }
    protected override void BeforeProceed(IInvocation invocation)
    {
        _logger.LogInformation($"ServiceAop调用方法：{invocation.Method.Name}，参数：{JsonConvert.SerializeObject(invocation.Arguments) }");
    }

    protected override void AfterProceedSync(IInvocation invocation)
    {
        _logger.LogInformation($"ServiceAop同步返回结果：{JsonConvert.SerializeObject(invocation.ReturnValue)}");
    }

    protected override void AfterProceedAsync(IInvocation invocation, bool hasAsynResult)
    {
        _logger.LogInformation($"ServiceAop异步返回结果：{JsonConvert.SerializeObject(invocation.ReturnValue)}");
    }
}

两个类放在了新建的Aop文件夹里，通过Autofac注入进行使用，修改 Startup.cs 代码如图：（不太明白的请看：（五）Autofac）

3、使用效果

二、前人栽树，后人乘凉

https://blog.csdn.net/q932104843/article/details/97611912
https://www.cnblogs.com/wswind/p/13863104.html