ExceptionMiddleware .net核心中的责任链 [英] Chain of responsibility in ExceptionMiddleware .net core

问题描述

是否可以在.net核心中间件中实现类似于责任链模式的功能，以捕获异常?因为我想全局处理异常并将其带给处理程序. 例子

is it possible to implement something similar to chain of responsibility pattern in .net core middleware which catches exceptions? Because I wanted to Handle exceptions globally and take them to their handlers. Example

try
{
}
catch(CustomException1 ex)
{
}
catch(CustomException2 ex)
{
}
...

中间件的增长非常快，以后很难维护.我想try{} catch(Exception e) { Handle(e); }并为每个异常创建处理程序，例如NullReference等的处理程序.我想通过类型来获取异常并在指定处理程序中的handle()方法中处理该异常的解决方案.

The middleware grows really fast and it will be hard to maintain later. I wanted to try{} catch(Exception e) { Handle(e); } and make Handlers for each Exception, for example handler for NullReference etc. I though about solution to take the exception by type and handle it in the handle() method in the specified handler.

推荐答案

我正在玩中间件，所以在启动时:

I'm toying around with middleware, so in startup:

app.UseMiddleware<ErrorHandlingMiddleware>();

中间件，我有一个通用的异常处理程序，您可以在此处添加很多(示例代码，Sentry是错误日志服务... sentry.io):

Middleware, I have one general exception handler, you could add many here (sample code, Sentry is an error log service...sentry.io):

public class ErrorHandlingMiddleware
{
    private readonly RequestDelegate _next;
    private readonly IHub _sentry;

    public ErrorHandlingMiddleware(RequestDelegate next, IHub sentry)
    {
        _sentry = sentry;
        _next = next;
    }

    public async Task Invoke(HttpContext context/* other dependencies */)
    {
        try
        {
            await _next(context).ConfigureAwait(false);
        }
        catch (Exception ex)
        {
            await HandleExceptionAsync(context, ex).ConfigureAwait(false);
        }
    }

    private Task HandleExceptionAsync(HttpContext context, Exception exception)
    {
        var code = HttpStatusCode.InternalServerError; // 500 if unexpected

        if (exception is ValueNotAcceptedException) code = HttpStatusCode.NotAcceptable;
        /*if (exception is MyNotFoundException) code = HttpStatusCode.NotFound;
        else if (exception is MyUnauthorizedException) code = HttpStatusCode.Unauthorized;
        else if (exception is MyException) code = HttpStatusCode.BadRequest;*/

        // send to Sentry.IO
        _sentry.CaptureException(exception);

        var result = JsonConvert.SerializeObject(new { error = exception.Message });

        context.Response.ContentType = "application/json";
        context.Response.StatusCode = (int)code;

        return context.Response.WriteAsync(result);
    }

请注意，在构造函数中添加依赖项会使它成为单例，持续应用程序的生命周期(在我的情况下还可以)，或者在Invoke中添加依赖项.

Note adding a dependency in the constructor will make it a singleton, last the life-cycle of the app (in my case it's fine), or else add dependency in the Invoke.

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