官方建議用app.UseExceptionHandler("/error")來集中處理異常，本例是一個具體的應用。

比如項目中有一個ViewModel，要求Name最大長度為5

/// <summary>/// 用戶模型/// </summary>public class UserModel{/// <summary>/// ID/// </summary>public int ID { get; set; }/// <summary>///名稱///?</summary>??[MaxLength(5, ErrorMessage = "長度不能超過5")]public string Name { get; set; }}

在TestController中有兩個Action，都有異常的機率，Get方法中，一個異常是系統內置的0被整除，另一個是我們自定義的業務層級異常(.NET架構小技巧（8）中有涉及);AddUser是有Model驗證有可能Name超過5個字符后報異常。Error方法一個錯誤處理Action，根據上下文的異常來分流系統內置異常，還是自定業務異常。

????????///?<summary>/// get接口/// </summary>/// <returns></returns>[HttpGet]public IActionResult Get(){var ran = new Random();switch (ran.Next(1, 4)){case 1:int i = 0;var j = 10 / i;return Ok();case 2:throw new RegisteredException("這是一個錯誤");default:return Ok();}}/// <summary>///?添加用戶接口/// </summary>/// <param name="user"></param>/// <returns></returns>[HttpPost("/adduser")]public IActionResult AddUser([FromBody] UserModel user){return Ok(user);}///?<summary>/// 錯誤處理頁/// </summary> /// <returns></returns>[HttpGet("/error")]public IActionResult Error(){var context = HttpContext.Features.Get<IExceptionHandlerFeature>();//如果是業務自定義異常，進行特殊處理if (context.Error is DaMeiException){return Problem(detail: context.Error.StackTrace, title: $"{context.Error.Message}", type: "HIS");}else{return Problem(detail: context.Error.StackTrace, title: context.Error.Message);}}

層級異常類

using?System; namespace WebApiError {/// <summary>/// 產品異常/// </summary>public class DaMeiException : ApplicationException{/// <summary>/// /// </summary>/// <param name="message"></param>public DaMeiException(string message) : base(message){}}/// <summary>/// His項目異常/// </summary>public class HisException : DaMeiException{/// <summary>/// /// </summary>/// <param name="message"></param>public HisException(string message) : base(message){}}/// <summary>/// Lis項目異常/// </summary>public class LisException : DaMeiException{/// <summary>/// /// </summary>/// <param name="message"></param>public LisException(string message) : base(message){}}/// <summary>/// 模塊異常/// </summary>public class RegisteredException : HisException{/// <summary>/// /// </summary>/// <param name="message"></param>public RegisteredException(string message) : base(message){}} }

Error的Action之所有調用到，是因為Configure中添加如下代碼，把所有異常交給"/error"來處理。

app.UseExceptionHandler("/error");

添加DaMeiProblemDetailsFactory來兼容各類異常，自定義異常和Model驗證異常

using Microsoft.AspNetCore.Http; using Microsoft.AspNetCore.Mvc; using Microsoft.AspNetCore.Mvc.Infrastructure; using Microsoft.AspNetCore.Mvc.ModelBinding; using System.Collections.Generic;namespace WebApiError {///?<summary>/// /// </summary>public class DaMeiProblemDetailsFactory : ProblemDetailsFactory{/// <summary>///?處理業務錯誤/// </summary>/// <param name="httpContext"></param>/// <param name="statusCode"></param>/// <param name="title"></param>/// <param name="type"></param>/// <param name="detail"></param>/// <param name="instance"></param>/// <returns></returns>public override ProblemDetails CreateProblemDetails(HttpContext httpContext, int? statusCode = null, string title = null, string type = null, string detail = null, string instance = null){var problem = new ProblemDetails(){Title = string.IsNullOrEmpty(type) ? title : $"業務異常錯誤：{title}",Detail = detail,Status = statusCode,Instance = instance,Type?=?type};return problem;}/// <summary>/// 處理model驗證錯誤/// </summary>/// <param name="httpContext"></param>/// <param name="modelStateDictionary"></param>/// <param name="statusCode"></param>/// <param name="title"></param>/// <param name="type"></param>/// <param name="detail"></param>/// <param name="instance"></param>/// <returns></returns>public override ValidationProblemDetails CreateValidationProblemDetails(HttpContext httpContext, ModelStateDictionary modelStateDictionary, int? statusCode = null, string title = null, string type = null, string detail = null, string instance = null){var problem = new ValidationProblemDetails(){Title = "Model驗證錯誤",Detail = detail,Status = statusCode,Instance = instance,Type = type};foreach (var a in modelStateDictionary){var errorList = new List<string>();foreach (var error in a.Value.Errors){errorList.Add(error.ErrorMessage);}problem.Errors.Add(new KeyValuePair<string, string[]>(a.Key, errorList.ToArray()));}return problem;}} }

在ConfigureServices中需要注入DaMeiProblemDetailsFactory

services.AddTransient<ProblemDetailsFactory, DaMeiProblemDetailsFactory>();

其實還可以用Action過濾器來統一管理異常

using Microsoft.AspNetCore.Mvc; using Microsoft.AspNetCore.Mvc.Filters;namespace WebApiError {/// <summary>/// 自定義過濾器處理異常/// </summary>public class DaMeiExceptionFilter : IActionFilter, IOrderedFilter{/// <summary>/// /// </summary>public int Order { get; } = int.MaxValue - 10;/// <summary>/// /// </summary>/// <param name="context"></param>public void OnActionExecuting(ActionExecutingContext context) { }/// <summary>/// /// </summary>/// <param name="context"></param>public void OnActionExecuted(ActionExecutedContext context){if (context?.Exception != null){context.Result = new ObjectResult(context.Exception.Message){StatusCode = 500};context.ExceptionHandled = true;} }} }

另外一種方式是通過Action過濾器來處理

using Microsoft.AspNetCore.Mvc; using Microsoft.AspNetCore.Mvc.Filters;namespace WebApiError {/// <summary>/// 自定義過濾器處理異常/// </summary>public class DaMeiExceptionFilter : IActionFilter, IOrderedFilter{/// <summary>/// /// </summary>public int Order { get; } = int.MaxValue - 10;/// <summary>/// /// </summary>/// <param name="context"></param>public void OnActionExecuting(ActionExecutingContext context){}/// <summary>/// /// </summary>/// <param name="context"></param>public void OnActionExecuted(ActionExecutedContext context){if (context?.Exception != null){if (context.Exception is DaMeiException){context.Result = new ObjectResult(context.Exception.Message){Value = $"業務異常：{ context.Exception.Message}",StatusCode = 500};}else{context.Result = new ObjectResult(context.Exception.Message){Value = context.Exception.Message,StatusCode = 500};}context.ExceptionHandled = true;}}} }

添加全局過濾器

services.AddControllers(options => {options.Filters.Add(new?DaMeiExceptionFilter()); });

總結

以上是生活随笔為你收集整理的asp.net core web api之异常的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。