（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