从 WebApi 错误 HttpResponseMessage 获取图像

Question

您好，我有 Web 中的方法 Api 获取个人形象的服务

 public HttpResponseMessage GetPersonnelPicture( int personnelId)
    {
        JamsazERPLiteEntities db = new JamsazERPLiteEntities();

        var fingerPrint = db.FingerPrints.FirstOrDefault(c => c.SequenceNumber == fingerNumber && c.MAC == MAC && !c.IsDeleted);

        if (fingerPrint != null && fingerPrint.Personnel != null)
        {
            try
            {
                var result = new HttpResponseMessage(HttpStatusCode.OK);
                FileStream fileStream =
                    new FileStream(@"\atlas\Personnel Pictures\" + personnelId + ".jpg",
                        FileMode.Open);
                Image image = Image.FromStream(fileStream);
                MemoryStream memoryStream = new MemoryStream();
                image.Save(memoryStream, ImageFormat.Jpeg);
                result.Content = new ByteArrayContent(memoryStream.ToArray());
                result.Content.Headers.ContentType = new MediaTypeHeaderValue("image/jpeg");
                memoryStream.Close();
                memoryStream.Dispose();
                fileStream.Close();
                fileStream.Dispose();

                return result;
            }
            catch { }
        }

        return null;
    }

当运行 Web 服务在 visual studio 2017 中在 IIS Express 中成功发送来自客户端的请求（我通过 Postman 应用程序从发送请求 localhost:23254/api/Weight/GetPersonnelPicture/?personnelId=2154 进行测试）

但是当发布到本地 IIS 时，我收到 Postman 应用程序的流动错误

{ "Message": "An error has occurred.", "ExceptionMessage": "A null value was returned where an instance of HttpResponseMessage was expected.", "ExceptionType": "System.InvalidOperationException", "StackTrace": " at System.Web.Http.Controllers.ResponseMessageResultConverter.Convert(HttpControllerContext controllerContext, Object actionResult)\r\n at System.Web.Http.Controllers.ApiControllerActionInvoker.d__0.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at System.Web.Http.Controllers.ActionFilterResult.d__2.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at System.Web.Http.Dispatcher.HttpControllerDispatcher.d__0.MoveNext()" }

Answer 1

您需要先定义 httpwebrequest，然后才能期望来自该 http 服务器的响应。

         HttpWebRequest request = (HttpWebRequest)WebRequest.Create("httpurl");
                using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
                {
                    using (StreamReader reader = new StreamReader(response.GetResponseStream()))
                    {
                      //your code
                    }
                }

Answer 2

在 IIS 7（而非 IIS 7.5）中，站点根据在站点的应用程序池中设置的帐户访问文件和文件夹。默认情况下，在 IIS7 中，此帐户为 NETWORK SERVICE。

为应用程序池 (IIS 7) 指定标识

在 IIS 7.5（Windows 2008 R2 和 Windows 7）中，应用程序池运行在应用程序池启动时创建的 ApplicationPoolIdentity 下。如果要为此帐户设置 ACLS，则需要选择 IIS AppPool\ApplicationPoolName 而不是 NT Authority\Network 服务。 Answer Here

从 WebApi 错误 HttpResponseMessage 获取图像

Get Image From WebApi Error HttpResponseMessage

c#

asp.net-web-api

httpresponsemessage