.net core 拦截器和全局异常捕获

1.编写全局异常拦截类

public class MyExpextFilter : ExceptionFilterAttribute
    {
        private ILogger<MyExpextFilter> logger;
        public MyExpextFilter(ILogger<MyExpextFilter> logger)
        {
            this.logger = logger;
        }
        public override void OnException(ExceptionContext context)
        {
            if (!context.ExceptionHandled) //如果错误没有处理过
            {
                if (this.IsAjax(context.HttpContext.Request))
                {
                    context.Result = new JsonResult(new VReturnMessage<object> //
                    {
                        Message = context.Exception.Message,
                        ReturnCode = context.HttpContext.Response.StatusCode,
                        Data = new List<object>()
                    });
                }
                logger.LogError(context.Exception.Message);
                context.ExceptionHandled = true; //表示错误已经处理过
            }
        }

        public override Task OnExceptionAsync(ExceptionContext context)
        {
            this.OnException(context);
            return Task.CompletedTask;
        }

        //header中 x-requested-with  XMLHttpRequest  //表明是AJax异步
        private bool IsAjax (HttpRequest httpRequest)
        {
            string requestType = httpRequest.Headers["x-requested-with"];
            return "XMLHttpRequest".Equals(requestType, StringComparison.Ordinal);
        }
    }

2. 注册拦截器

2.1 ServiceFilter 注册

在需要拦截的地方增加特性 [ServiceFilter(typeof(MyExpextFilter))] 并在ConfigureServices 中注册MyExpextFilter   ->  services.AddScoped(typeof(MyExpextFilter));

2.2 TypeFilter 注册

在需要拦截的地方增加特性 [TypeFilter(typeof(MyExpextFilter))] 此方式不需要在ConfigureServices 中注册

2.3 FilterFactory 注册

编写拦截Factory 类

    public class ExpertFilterFactory : Attribute,IFilterFactory
    {
        public bool IsReusable => true;

        public IFilterMetadata CreateInstance(IServiceProvider serviceProvider)
        {
            return serviceProvider.GetService(typeof(MyExpextFilter)) as IFilterMetadata;
        }
    }

在需要拦截的地方增加特性 [ExpertFilterFactory] 并在ConfigureServices 中注册MyExpextFilter   ->  services.AddScoped(typeof(MyExpextFilter));

2.4 全局注册

services.AddControllersWithViews(opetation =>
{
　　opetation.Filters.Add<MyExpextFilter>();
 });

3. Filter拦截顺序

用order参数 从小到大开始