如何使用Castle Core或其他库(仅免费库)编写Interceptor(AOP)，以解决横切问题 [英] How can I write Interceptor (AOP) with Castle Core or Other libraries (just free libraries) for Cross Cutting Concerns

问题描述

我想为诸如日志记录"，异常"，"..."之类的横切关注点"具有这样的属性.

I want to have an attribute like this for Cross Cutting Concerns like Logging , Exception , ...

public class MyService
{

[Log] // Interception (AOP)
[ExceptionHandler] // Interception (AOP)
public void DoSomething()
   {

   }
}

我知道我可以用postharp编写这些代码，但是我想用免费的库(例如Castle Core和...

I know that I can write these codes with postsharp but I want to write these interceptions with free libraries like Castle Core and ...

任何人都可以帮助我并为此目的编写示例吗??? 我需要一个非常简单的示例来学习概念

Can anyone help me and write a sample for these purpose ??? I need a very simple sample for learning concepts

推荐答案

Autofac是一个免费的IoC容器.我将Autofac与Autofac.Extras.DynamicProxy2 nuget ，

Autofac is a free IoC container. I use Autofac with Autofac.Extras.DynamicProxy2 nuget, docs.

假设您知道为什么(何时)(不使用)拦截器，并且想拦截某些功能:

Assuming you know why and when to (and not to) use interceptors, and you want to intercept some functionality:

public class FooService : IFooService
{
    public void MoreFoo()
    {
        DoSomething();
    }
    public void LessFoo()
    {
        DoSomethingElse();
    }
}

它需要连接".我喜欢属性，因为您无需在IoC容器接线时显式指定拦截器.您只需指定要注意的属性即可:

It needs to be "wired". I like attributes as you don't need to explicitly specify the interceptor at IoC container wiring. You just specify an attribute to watch out for:

[Intercept(typeof(Logger)]
public class FooService : IFooService { ... }

并连接:

var builder = new ContainerBuilder();
builder.RegisterType<FooService>()
   .EnableClassInterceptors();

然后在另一个文件中创建Logger拦截器:

Then create your Logger interceptor in another file:

class Logger : IInterceptor
{
    public void Intercept(IInvocation invocation) // implements the IInterceptor interface
    {
        _loggerService.Log("calling " + invocation.Method.Name);
        invocation.Proceed();
        _loggerService.Log("finished " + invocation.Method.Name);
    }
}

如您所见，您可以创建计时器，try-catch块等.数据库上下文和其他可抛弃资源是一个有趣的资源:

As you can see, you can create timers, try-catch blocks, and much more. Database context and other disposable resources is an interesting one:

class Logger : IInterceptor
{
    public void Intercept(IInvocation invocation) // implements the IInterceptor interface
    {
        using (var someThing = new SomeResource())
        {
            invocation.Proceed();
        }
    }
}

通常使用这种资源，您需要在方法内部使用someThing.这是另一个问题的话题！ (请参阅invocation.SetArgumentValue或invocation.TargetType.GetProperties()以与封闭类进行通信.我对此不是100％满意，因此其他人的一些评论会有所帮助)

Usually with such a resource you need to use someThing inside your method. That's a topic for another question! (see invocation.SetArgumentValue or invocation.TargetType.GetProperties() to communicate to the enclosing class. I'm not 100% comfortable with this, so some comments from others would be helpful)

然后，以日志记录为例:

Then, take a logging as an example:

void ManageFoo()
{
    // sorry for the messy code, what else can I do?!
    _logger("more foo please");
    _fooService.MoreFoo();
    _logger("less foo please");
    _fooService.LessFoo();
    _logger("enough foo");
}

ManageFoo方法的实际问题在所有混乱的日志中都丢失了(增加安全性和其他问题，最终可能会造成很大的麻烦).

The actual concern of the ManageFoo method is lost in all the mess of logging (add security and other concerns and you can end up with a big mess).

现在您可以像这样重写它:

Now you can rewrite it like this:

void ManageFoo()
{
    _fooService.MoreFoo();
    _fooService.LessFoo();
}

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