我在我的Mvc\WebApi应用程序中注册了一个全局的异常过滤器：
public virtual void RegisterHttpFilters(HttpConfiguration config)
{
config.Filters.Add(new MyExceptionFilter(_exceptionHandler));
}
MyExceptionFilter是什么：
public class MyExceptionFilter : ExceptionFilterAttribute
{
private readonly IMyExceptionHandler m_exceptionHandler;
public MyExceptionFilter(IMyExceptionHandler exceptionHandler)
{
m_exceptionHandler = exceptionHandler;
}
public override void OnException(HttpActionExecutedContext context)
{
Exception ex = context.Exception;
if (ex != null)
{
object response = null;
HttpStatusCode statusCode = m_exceptionHandler != null
? m_exceptionHandler.HandleException(ex, out response)
: HttpStatusCode.InternalServerError;
context.Response = context.Request.CreateResponse(statusCode, response ?? ex);
}
base.OnException(context);
}
}
这个过滤器将所有的异常返回为JSON对象，并允许IMyExceptionHandler实现自定义返回的对象。
一切都很顺利，直到我的一些消息处理程序发生异常：
public class FooMessageHandler : DelegatingHandler
{
private readonly Func<IBar> _barFactory;
public FooMessageHandler(Func<IBar> barFactory)
{
_barFactory = varFactory;
}
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
request.Properties["MY_BAR"] = _barFactory();
return base.SendAsync(request, cancellationToken);
}
}
从该处理程序中可以看出，它创建一些组件并将其放入当前的HTTP请求消息中。当FuncOfIBar中发生异常时，我会得到 Yellow Screen of Death，我的 ExceptionFilter 没有被调用。
我尝试在消息处理程序中特定地捕获异常并返回 HttpResponseException，但是它并没有改变任何东西 - 仍然会收到 YSOD：
public class XApplicationInitializerMessageHandler : DelegatingHandler
{
private readonly Func<IXCoreApplication> _appFactory;
private readonly IXExceptionHandler m_exceptionHandler;
public XApplicationInitializerMessageHandler(Func<IXCoreApplication> appFactory, IXExceptionHandler exceptionHandler)
{
ArgumentValidator.EnsureArgumentNotNull(appFactory, "appFactory");
_appFactory = appFactory;
m_exceptionHandler = exceptionHandler;
}
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
try
{
request.SetApplication(_appFactory());
}
catch (Exception ex)
{
object resultObject = null;
HttpStatusCode statusCode = m_exceptionHandler != null
? m_exceptionHandler.HandleException(ex, out resultObject)
: HttpStatusCode.InternalServerError;
HttpResponseMessage responseMessage = request.CreateResponse(statusCode, resultObject ?? ex);
throw new HttpResponseException(responseMessage);
}
return base.SendAsync(request, cancellationToken);
}
}
我希望无论异常发生在ApiController还是消息处理程序中，我的应用程序行为都相同。
如何实现？
我知道Application_Error，但我想保持HttpApplication的自定义不变。