当ExceptionHandlerMiddleware运行时，截获响应时发生异常

Question

我一辈子都想不出如何解决这个问题。请帮忙。为了简化和复制，我在VS2019中复制了.NetCore3.1MVC模板，并添加了相关部分。

我有一个拦截器中间件，它记录所有请求和响应，并使用Home/Error视图来显示发生了错误。

当调用成功时，拦截器会很好地记录请求和响应。但是，如果管道中发生异常，则响应拦截器将失败，并在中出现错误Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware，并显示HTTP 500错误而不是Home/error视图。

An exception was thrown attempting to execute the error handler.
System.ObjectDisposedException: Cannot access a closed Stream.
Object name: 'destination'.
at System.IO.StreamHelpers.ValidateCopyToArgs(Stream source, Stream destination, Int32 bufferSize)
at System.IO.MemoryStream.CopyToAsync(Stream destination, Int32 bufferSize, CancellationToken cancellationToken)
at System.IO.Stream.CopyToAsync(Stream destination)
at Test.Middleware.Interceptor.Invoke(HttpContext context) in C:Usersmicher03sourcerepostestMiddlewareInterceptor.cs:line 30
at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.HandleException(HttpContext context, ExceptionDispatchInfo edi)

启动.cs

namespace Test
{
public class Startup
{
public Startup(IConfiguration configuration, IHostEnvironment hostingEnvironment)
{
Configuration = configuration;
var builder = new ConfigurationBuilder()
.SetBasePath(hostingEnvironment.ContentRootPath)
.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
.AddEnvironmentVariables();
Configuration = builder.Build();
Log.Information("Application Starting");
}
public IConfiguration Configuration { get; }
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
services.AddControllersWithViews();
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
app.UseExceptionHandler("/Home/Error");
app.UseMiddleware<Interceptor>();
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapControllerRoute(
name: "default",
pattern: "{controller=Home}/{action=Index}/{id?}");
});
}
}
}

错误.cshtml

@model ErrorViewModel
@{
ViewData["Title"] = "Error";
}
<h1 class="text-danger">Error.</h1>
<h2 class="text-danger">An error occurred while processing your request.</h2>

拦截器

using System;
using System.IO;
using System.Text;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Serilog;
namespace Test.Middleware
{
public class Interceptor
{
private readonly RequestDelegate _nextRequest;
public Interceptor(RequestDelegate nextRequest)
{
_nextRequest = nextRequest;
}
public async Task Invoke(HttpContext context)
{
await LogRequest(context.Request);
var originalBodyStream = context.Response.Body;
using (var responseBody = new MemoryStream())
{
context.Response.Body = responseBody;
await _nextRequest(context);
await LogResponse(context.Response);
await responseBody.CopyToAsync(originalBodyStream);
}
}
private async Task<string> LogRequest(HttpRequest request)
{
HttpRequestRewindExtensions.EnableBuffering(request);
var buffer = new byte[Convert.ToInt32(request.ContentLength)];
await request.Body.ReadAsync(buffer, 0, buffer.Length);
var bodyAsText = Encoding.UTF8.GetString(buffer);
request.Body.Seek(0, SeekOrigin.Begin);
Log.Information("Request {Path} {Body}", request.Path, bodyAsText);
return "OK";
}
private async Task<string> LogResponse(HttpResponse response)
{
response.Body.Seek(0, SeekOrigin.Begin);
string bodyAsText = await new StreamReader(response.Body).ReadToEndAsync();
response.Body.Seek(0, SeekOrigin.Begin);
Log.Information("Response {@StatusCode} {@Body}", response.StatusCode, bodyAsText);
return "OK";
}
}
}

Answer 1

响应内存流到达DeveloperExceptionPageMiddleware或ExceptionHandlerMiddleware时关闭

如果抛出异常，您需要在拦截器中设置回原始流

public async Task Invoke(HttpContext context)
{
await LogRequest(context.Request);
var originalBodyStream = context.Response.Body;
using (var responseBody = new MemoryStream())
{
context.Response.Body = responseBody;
try {
await _nextRequest(context);
} 
catch
{
if(!context.Response.HasStarted)
{
context.Response.Body = originalResponseStream;
}
throw;
}

await LogResponse(context.Response);
await responseBody.CopyToAsync(originalBodyStream);
}
}