写入 HttpContext 时出现 System.ObjectDisposedException

Question

我在我的 rest api 项目中制作了自定义异常中间件：

public async Task InvokeAsync(HttpContext httpContext)              
{                                                                   
    try                                                             
    {                                                               
        await _next(httpContext);                                   
    }                                                                                                                           
    catch (Exception ex)                                            
    {                                                               
        _logger.Error($"{ex}");               
        await HandleExceptionAsync(httpContext);                    
    }                                                               
}    

private Task HandleExceptionAsync(HttpContext context)          
{                                                               
    context.Items.Clear();                                      
    context.Response.StatusCode = StatusCodes.Status200OK;      
    context.Response.ContentType = "application/json";          
                                                                
    return context.Response.WriteAsync("Internal Server Error");
}                                                                    

当捕获到一些异常时，我收到错误：

System.NullReferenceException: Object reference not set to an instance of an object.
  ?, in Task SaveTempDataFilter.OnStarting(HttpContext httpContext)
  ?, in Task HttpProtocol.FireOnStartingMayAwait(Stack<KeyValuePair<Func<object, Task>, object>> onStarting)
System.ObjectDisposedException: The response has been aborted due to an unhandled application exception.
  ?, in void HttpProtocol.ThrowResponseAbortedException()
  ?, in Task HttpProtocol.InitializeResponseAsync(int firstWriteByteCount)
  ?, in Task HttpProtocol.Microsoft.AspNetCore.Http.Features.IHttpResponseBodyFeature.StartAsync(CancellationToken cancellationToken)
  ?, in Task DefaultHttpResponse.StartAsync(CancellationToken cancellationToken)
  ?, in Task HttpResponseWritingExtensions.WriteAsync(HttpResponse response, string text, Encoding encoding, CancellationToken cancellationToken) x 2
  File "/Middleware/ExceptionWrapperMiddleware.cs", line 57, col 13, in Task ExceptionWrapperMiddleware.HandleExceptionAsync(HttpContext context)
  File "/Middleware/ExceptionWrapperMiddleware.cs", line 50, col 9, in async Task ExceptionWrapperMiddleware.InvokeAsync(HttpContext httpContext)
  File "/_/src/Sentry.AspNetCore/SentryMiddleware.cs", line 139, col 9, in async Task SentryMiddleware.InvokeAsync(HttpContext context)

我的问题是，我的代码同时得到 Null Reference Exception 和 ObjectDisposedException 有什么问题？

Answer 1

根据堆栈跟踪，当您调用context.Response.WriteAsync("Internal Server Error");时， HttpResponseWritingExtensions.WriteAsync会引发异常context.Response.WriteAsync("Internal Server Error"); 方法。 您只需要等待WriteAsync方法，而不是返回任务。

private async Task HandleExceptionAsync(HttpContext context)          
{                                                         
     context.Items.Clear();                                      
     context.Response.StatusCode = StatusCodes.Status200OK;      
     context.Response.ContentType = "application/json";          
                                                            
     return await context.Response.WriteAsync("Internal Server Error");
}