如何在 .NET Core 中捕获异常并使用状态代码进行响应 [英] How to catch an exception and respond with a status code in .NET Core
问题描述
我正在运行一个 .Net Core Web API 项目.我有一个启动文件(如下).在 Startup.ConfigureServices(...)
方法中,我添加了一个创建 IFoo 实例的工厂方法.我想捕获 IFooFactory 抛出的任何异常并返回带有状态代码的更好的错误消息.目前,我收到 500 错误和异常消息.有人可以帮忙吗?
I am running a .Net Core Web API project.
I have a startup file (below). In the Startup.ConfigureServices(...)
method, I add a factory method that creates an instance of IFoo. I want to catch any exceptions that the IFooFactory throws and return a better error message with a status code. At the moment I getting a 500 Error with the exception Message. Can anyone help?
public interface IFooFactory
{
IFoo Create();
}
public class FooFactory : IFooFactory
{
IFoo Create()
{
throw new Exception("Catch Me!");
}
}
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddScoped<IFooFactory,FooFactory>();
services.AddScoped(serviceProvider => {
IFooFactory fooFactory = serviceProvider.GetService<IFooFactory>();
return fooFactory.Create(); // <== Throws Exception
});
}
}
推荐答案
所以当我以两种不同的方式阅读问题时,我发布了两个不同的答案 - 大量删除/取消删除/编辑 - 不确定哪一个真正回答了您的问题问题:
So I've posted two different answers as I read the question in two different ways - lots of deleting/undeleting/editing - not sure which one actually answers your question:
要找出应用启动时出了什么问题并且根本无法运行,请尝试以下操作:
在Startup
中使用开发者异常页面:
Use the developer exception page in Startup
:
public void Configure(IApplicationBuilder app, IHostingEnvironment env,
ILoggerFactory loggerFactory)
{
app.UseDeveloperExceptionPage();
}
在 Program
类中:
public static void Main(string[] args)
{
var host = new WebHostBuilder()
.UseKestrel()
.UseContentRoot(Directory.GetCurrentDirectory())
.UseIISIntegration()
.UseStartup<Startup>()
.UseApplicationInsights()
.CaptureStartupErrors(true) // useful for debugging
.UseSetting("detailedErrors", "true") // what it says on the tin
.Build();
host.Run();
}
如果你想在 api 正常工作时处理偶尔的异常,那么你可以使用一些中间件:
public class ExceptionsMiddleware
{
private readonly RequestDelegate _next;
/// <summary>
/// Handles exceptions
/// </summary>
/// <param name="next">The next piece of middleware after this one</param>
public ExceptionsMiddleware(RequestDelegate next)
{
_next = next;
}
/// <summary>
/// The method to run in the piepline
/// </summary>
/// <param name="context">The current context</param>
/// <returns>As task which is running the action</returns>
public async Task Invoke(HttpContext context)
{
try
{
await _next.Invoke(context);
}
catch(Exception ex)
{
// Apply some logic based on the exception
// Maybe log it as well - you can use DI in
// the constructor to inject a logging service
context.Response.StatusCode = //Your choice of code
await context.Response.WriteAsync("Your message");
}
}
}
这有一个问题"——如果响应头已经发送,你就不能写状态码.
您使用 Configure
方法在 Startup
类中配置中间件:
You configure the middleware in the Startup
class using the Configure
method:
public void Configure(IApplicationBuilder app, IHostingEnvironment env,
ILoggerFactory loggerFactory)
{
app.UseMiddleware<ExceptionsMiddleware>();
}
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