使用中间件统一处理.Net 6 web应用的异常和错误

使用中间件统一处理.net 6 web应用的异常和错误只需要二步即可，分别是：创建错误处理中间件 和 注册错误处理中间件。具体如下：

1、创建错误处理中间件

using System.Net;
using System.Text.Json;

namespace Test.WebAPI.Middlewares.ExceptionHandler
{
    /// <summary>
    /// 全局异常处理中间件
    /// </summary>
    public class ExceptionHandlingMiddleware
    {
        private readonly RequestDelegate _next;  // 用来处理上下文请求 
        private readonly ILogger<ExceptionHandlingMiddleware> _logger; //日志
        public ExceptionHandlingMiddleware(RequestDelegate next, ILogger<ExceptionHandlingMiddleware> logger)
        {
            _next = next;
            _logger = logger;
        }

        public async Task InvokeAsync(HttpContext httpContext)
        {
            try
            {
                await _next(httpContext); //要么在中间件中处理，要么被传递到下一个中间件中去
            }
            catch (Exception ex)
            {
                await HandleExceptionAsync(httpContext, ex); // 捕获异常了 在HandleExceptionAsync中处理
            }
        }
        //此处统一处理错误异常
        private async Task HandleExceptionAsync(HttpContext context, Exception exception)
        {
            context.Response.ContentType = "application/json";  // 返回json 类型
            var response = context.Response;

            string message = exception.Message;
            int id = Convert.ToInt32(DateTime.Now.ToString("ddhhmmss"));
            switch (exception)
            {
                case ApplicationException ex:
                    if (ex.Message.Contains("Invalid token"))
                    {
                        response.StatusCode = (int)HttpStatusCode.Forbidden;
                        break;
                    }
                    response.StatusCode = (int)HttpStatusCode.BadRequest;
                    break;
                case KeyNotFoundException ex:
                    response.StatusCode = (int)HttpStatusCode.NotFound;
                    break;
                case ArgumentException ex:
                    response.StatusCode = (int)HttpStatusCode.BadRequest;
                    break;
                default:
                    response.StatusCode = (int)HttpStatusCode.InternalServerError;
                    message = "程序内部错误[" + id + "]，请联系管理员";
                    break;
            }
            EventId eventId = new EventId(id);
            _logger.LogError(eventId, exception, exception.Message);
            var result = JsonSerializer.Serialize(new { message = message, result = false, code = response.StatusCode });
            await context.Response.WriteAsync(result);
            return;
        }
    }
}

2、在Program.cs中注册错误处理中间件

//启用全局错误捕获中间件
app.UseMiddleware<ExceptionHandlingMiddleware>();