dotNet8 全局异常处理

前言

异常的处理在我们应用程序中是至关重要的,在 dotNet 中有很多异常处理的机制,比如MVC的异常筛选器, 管道中间件定义try catch捕获异常处理亦或者第三方的解决方案Hellang.Middleware.ProblemDetails等。MVC异常筛选器不太灵活,对管道的部分异常捕获不到,后两种方式大家项目应该经常出现。

dotNet8 发布之后支持了新的异常处理机制 IExceptionHandler或者UseExceptionHandler异常处理程序的lambda配置,配合dotNet7原生支持的ProblemDetail使得异常处理更加规范。

本文用一个简单的 Demo 带大家看一下新的异常处理方式

文末有示例完整的源代码

先起一个 WebApi 的新项目

Problem Details

Problem Details 是一种在 HTTP API 中用于描述错误信息的标准化格式。根据 RFC 7807,Problem Details 提供了一种统一、可机器读取的方式来呈现出发生在 API 请求中的问题。它包括各种属性,如 title、status、detail、type 等,用于清晰地描述错误的性质和原因。通过使用 Problem Details,开发人员可以为 API 的错误响应提供一致性和易于理解的结构化格式,从而帮助客户端更好地处理和解决问题。

项目中使用 Problem Details

builder.Services.AddProblemDetails();

如果我们不对异常进行捕获处理,Asp.Net Core 提供了两种不同的内置集中式机制来处理未经处理的异常

  • app.UseDeveloperExceptionPage();

    开发人员异常中间件

    开发人员异常中间件会显示服务器错误的详细堆栈跟踪,不建议在非开发环境显示,暴漏核心错误信息给客户端,有严重的安全风险

  • app.UseExceptionHandler(); 异常处理程序中间件,
    使用异常处理程序中间件生成的是标准的简化回复

测试 UseDeveloperExceptionPage

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
builder.Services.AddProblemDetails();
var app = builder.Build();
app.MapGet("/TestUseDeveloperExceptionPage",
    () => { throw new Exception("测试UseDeveloperExceptionPage"); });
// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
    app.UseDeveloperExceptionPage();// 开发人员异常页
}
app.UseStatusCodePages();
app.UseHttpsRedirection();
app.Run();

调用 TestUseDeveloperExceptionPage 接口
回参

{
  "type": "https://tools.ietf.org/html/rfc9110#section-15.6.1",
  "title": "System.Exception",
  "status": 500,
  "detail": "测试UseDeveloperExceptionPage",
  "exception": {
    "details": "System.Exception: 测试UseDeveloperExceptionPage\r\n   at Program.<>c.<<Main>$>b__0_0() in C:\\dotNetParadise\\dot-net-paradise-exception\\dotNetParadise-Exception\\dotNetParadise-Exception\\Program.cs:line 7\r\n   at lambda_method3(Closure, Object, HttpContext)\r\n   at Microsoft.AspNetCore.HttpsPolicy.HttpsRedirectionMiddleware.Invoke(HttpContext context)\r\n   at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)\r\n   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)",
    "headers": {
      "Accept": [
        "*/*"
      ],
      "Host": [
        "localhost:7130"
      ],
      "User-Agent": [
        "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36 Edg/122.0.0.0"
      ],
      "Accept-Encoding": [
        "gzip, deflate, br"
      ],
      "Accept-Language": [
        "en-US,en;q=0.9"
      ],
      "Cookie": [
        "ajs_anonymous_id=b96604ea-c096-4693-acfb-b3a9e8403f0e; Quasar_admin_Vue3_username=admin; Quasar_admin_Vue3_token=b1aa15b6-02bb-44b9-8668-0157a1d9b6f0; Quasar_admin_Vue3_lang=en-US"
      ],
      "Referer": [
        "https://localhost:7130/swagger/index.html"
      ],
      "sec-ch-ua": [
        "\"Chromium\";v=\"122\", \"Not(A:Brand\";v=\"24\", \"Microsoft Edge\";v=\"122\""
      ],
      "sec-ch-ua-mobile": [
        "?0"
      ],
      "sec-ch-ua-platform": [
        "\"Windows\""
      ],
      "sec-fetch-site": [
        "same-origin"
      ],
      "sec-fetch-mode": [
        "cors"
      ],
      "sec-fetch-dest": [
        "empty"
      ]
    },
    "path": "/TestUseDeveloperExceptionPage",
    "endpoint": "HTTP: GET /TestUseDeveloperExceptionPage",
    "routeValues": {}
  }

可以看到所有的信息都抛出来给到了客户端,适合在开发环境用,非开发环境尤其是生产环境不要启用。

app.UseExceptionHandler();

异常处理程序中间件

// app.UseDeveloperExceptionPage();// 开发人员异常页
app.UseExceptionHandler();//异常处理中间件

测试一下

{
  "type": "https://tools.ietf.org/html/rfc9110#section-15.6.1",
  "title": "An error occurred while processing your request.",
  "status": 500
}

可以看到只保留了最基本的报错信息,这样第一步我们已经完成了。

自定义异常 和 IExceptionHandler

创建一个自定义异常信息

public class CustomException(int code, string message) : Exception(message)
{
    public int Code { get; private set; } = code;

    public string Message { get; private set; } = message;
}

集成IExceptionHandler创建自定义异常处理器

public class CustomExceptionHandler(ILogger<CustomException> logger, IWebHostEnvironment environment) : IExceptionHandler
{
    public async ValueTask<bool> TryHandleAsync(HttpContext httpContext, Exception exception, CancellationToken cancellationToken)
    {
        if (exception is not CustomException customException) return false;
        logger.LogError(
              exception, "Exception occurred: {Message} {StackTrace} {Source}", exception.Message, exception.StackTrace, exception.Source);

        var problemDetails = new ProblemDetails
        {
            Status = customException.Code,
            Title = customException.Message,
        };
        if (environment.IsDevelopment())
        {
            problemDetails.Detail = $"Exception occurred: {customException.Message} {customException.StackTrace} {customException.Source}";
        }
        httpContext.Response.StatusCode = problemDetails.Status.Value;
        await httpContext.Response
            .WriteAsJsonAsync(problemDetails, cancellationToken);
        return true;
    }
}

可以注册多个自定义异常处理器分别处理不同类型的异常,按默认的注册顺序来处理,如果返回true则会处理此异常返回false会跳到下一个ExceptionHandler,没处理的异常在 UseExceptionHandler 中间件做最后处理。

创建第二个ExceptionHandler 处理系统异常

public class SystemExceptionHandle(ILogger<CustomException> logger, IWebHostEnvironment environment) : IExceptionHandler
{
    public async ValueTask<bool> TryHandleAsync(HttpContext httpContext, Exception exception, CancellationToken cancellationToken)
    {
        if (exception is CustomException) return false;
        logger.LogError(
              exception, "Exception occurred: {Message} {StackTrace} {Source}", exception.Message, exception.StackTrace, exception.Source);

        var problemDetails = new ProblemDetails
        {
            Status = StatusCodes.Status500InternalServerError,
            Title = "An error occurred while processing your request",
        };
        if (environment.IsDevelopment())
        {
            problemDetails.Detail = $"Exception occurred: {exception.Message} {exception.StackTrace} {exception.Source}";
        }

        httpContext.Response.StatusCode = problemDetails.Status.Value;

        await httpContext.Response
            .WriteAsJsonAsync(problemDetails, cancellationToken);

        return true;

    }
}

IOC 容器注册ExceptionHandler

builder.Services.AddExceptionHandler<CustomExceptionHandler>();
builder.Services.AddExceptionHandler<SystemExceptionHandle>();

新加接口测试一下

app.MapGet("/CustomThrow", () =>
{
    throw new CustomException(StatusCodes.Status403Forbidden, "你没有权限!");
}).WithOpenApi();

回参

{
  "title": "你没有权限!",
  "status": 403,
  "detail": "Exception occurred: 你没有权限!    at Program.<>c.<<Main>$>b__0_1() in C:\\dotNetParadise\\dot-net-paradise-exception\\dotNetParadise-Exception\\dotNetParadise-Exception\\Program.cs:line 15\r\n   at lambda_method5(Closure, Object, HttpContext)\r\n   at Microsoft.AspNetCore.HttpsPolicy.HttpsRedirectionMiddleware.Invoke(HttpContext context)\r\n   at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)\r\n   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddlewareImpl.<Invoke>g__Awaited|10_0(ExceptionHandlerMiddlewareImpl middleware, HttpContext context, Task task) dotNetParadise-Exception"
}

可以看出全局异常捕获生效了。

最后

本文讲的是 dotNet8 新的异常处理方式,当时也可以用UseExceptionHandlerlambda方式可以创建,但是不如这种强类型约束的规范,大家在升级 dotNet8 时可以参考本文来修改项目现有的全部异常捕获方式。

Demo 源代码

dotNet 官网教程

posted @ 2024-03-15 11:56  董瑞鹏  阅读(3525)  评论(2编辑  收藏  举报