Asp.net Core WebApi 全局异常类

通过全局异常类，所有程序中遇到的错误都会被拦截，并友好的返回结果。

1、自定义一个全局异常处理类中间件

using Microsoft.AspNetCore.Http;
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Threading.Tasks;
using System.Xml.Serialization;
using UFX.Mall.EntityModel;
using UFX.Tools;

namespace UFX.Mall.WebApi
{
    public class ExceptionHandlerMiddleWare
    {
        private readonly RequestDelegate next;

        public ExceptionHandlerMiddleWare(RequestDelegate next)
        {
            this.next = next;
        }

        public async Task Invoke(HttpContext context)
        {
            try
            {
                await next(context);
            }
            catch (Exception ex)
            {
                await HandleExceptionAsync(context, ex);
            }
        }

        private static async Task HandleExceptionAsync(HttpContext context, Exception exception)
        {
            if (exception == null) return;
            await WriteExceptionAsync(context, exception).ConfigureAwait(false);
        }

        private static async Task WriteExceptionAsync(HttpContext context, Exception exception)
        {
            //记录日志
            LogHelper.Error(exception.GetBaseException().ToString());
            
            //返回友好的提示
            var response = context.Response;

            //状态码
            if (exception is UnauthorizedAccessException)
                response.StatusCode = (int)HttpStatusCode.Unauthorized;
            else if (exception is Exception)
                response.StatusCode = (int)HttpStatusCode.BadRequest;

            response.ContentType = context.Request.Headers["Accept"];

            if (response.ContentType.ToLower() == "application/xml")
            {
                await response.WriteAsync(Object2XmlString(ResultMsg.Failure(exception.GetBaseException().Message))).ConfigureAwait(false);
            }
            else
            {
                response.ContentType = "application/json";
                await response.WriteAsync(JsonConvert.SerializeObject(ResultMsg.Failure(exception.GetBaseException().Message))).ConfigureAwait(false);
            }
        }

        /// <summary>
        /// 对象转为Xml
        /// </summary>
        /// <param name="o"></param>
        /// <returns></returns>
        private static string Object2XmlString(object o)
        {
            StringWriter sw = new StringWriter();
            try
            {
                XmlSerializer serializer = new XmlSerializer(o.GetType());
                serializer.Serialize(sw, o);
            }
            catch
            {
                //Handle Exception Code
            }
            finally
            {
                sw.Dispose();
            }
            return sw.ToString();
        }

    }
}

返回值默认格式化成自定义类ResultMsg，可根据自己的项目需求，返回自定义实体

同时会根据客户端需要的格式，自动转换为xml或者json

2、configure注册

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddConsole(Configuration.GetSection("Logging"));
            loggerFactory.AddDebug();
            //配置NLog
            loggerFactory.AddNLog();
            env.ConfigureNLog("nlog.config");

            app.UseApplicationInsightsRequestTelemetry();

            app.UseApplicationInsightsExceptionTelemetry();

            //异常处理中间件
            app.UseMiddleware(typeof(ExceptionHandlerMiddleWare));

            app.UseMvc(); ;
        }