WebAPI添加全局异常过滤

在App_Start文件夹下的WebApiConfig.cs中加入如下代码：

  public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            // Web API 配置和服务

            // Web API 路由
            config.MapHttpAttributeRoutes();

            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{action}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );
            //全局异常过滤
            config.Filters.Add(new ApiExceptionAttribute());
        }
    }

新建ApiExceptionAttribute类：

public class ApiExceptionAttribute : ExceptionFilterAttribute
    {
        /// <summary>
        /// 控制器方法中出现异常，会调用该方法捕获异常
        /// </summary>
        /// <param name="filterContext">提供使用</param>
        public override void OnException(HttpActionExecutedContext filterContext)
        {

            HttpResponseMessage result = new HttpResponseMessage();
            result.Content = new StringContent(filterContext.Exception.Message);
            result.StatusCode = (HttpStatusCode)999;
            filterContext.Response = result;
            base.OnException(filterContext);
        }
    }