我需要从一个Mvc4应用程序发送文件到另一个(另一个是Mvc4,WebApi应用程序)。为了发送的目的,我使用HttpClient的PostAsync方法。以下是处理发送代码:等待PostAsync在mscorlib中抛出NullReferenceException
public class HomeController : Controller
{
public async Task<ActionResult> Index()
{
var result =
await Upload("http://localhost/target/api/test/post", "Test", System.IO.File.Open(@"C:\SomeFile", FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite));
return View(result);
}
public async Task<String> Upload(String url, string filename, Stream stream)
{
using (var client = new HttpClient())
{
var formData = new MultipartFormDataContent();
var fileContent = new StreamContent(stream);
var header = new ContentDispositionHeaderValue("attachment") { FileName = filename };
fileContent.Headers.ContentDisposition = header;
formData.Add(fileContent);
var result = await client.PostAsync(url, formData); // Use your url here
return "123";
}
}
}
用于接收的目的,我使用的官方网页API教程中的一个例子,在这里是做它的代码:
public class TestController : ApiController
{
// POST api/values
public Task<HttpResponseMessage> Post()
{
if (!Request.Content.IsMimeMultipartContent())
{
throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);
}
string root = HttpContext.Current.Server.MapPath("~/App_Data");
var provider = new MultipartFormDataStreamProvider(root);
// Read the form data and return an async task.
var task = Request.Content.ReadAsMultipartAsync(provider).ContinueWith(t =>
{
if (t.IsFaulted || t.IsCanceled)
{
return Request.CreateErrorResponse(HttpStatusCode.InternalServerError, t.Exception);
}
// This illustrates how to get the file names.
foreach (MultipartFileData file in provider.FileData)
{
Trace.WriteLine(file.Headers.ContentDisposition.FileName);
Trace.WriteLine("Server file path: " + file.LocalFileName);
}
return new HttpResponseMessage
{
Content = new StringContent("File uploaded.")
};
//var response = Request.CreateResponse(HttpStatusCode.OK);
//return response;
});
return task;
}
}
问题:
接收机获得文件成功,但是当它用下面的代码响应:
return new HttpResponseMessage
{
Content = new StringContent("File uploaded.")
};
发件人端在.Net的mscorlib内部内部深处发生了断裂。即使我用try/catch包装await
调用,也不处理异常。
我想保持异步实现,不想使用同步一个,这是可能的吗?为什么会出现这个问题?有什么想法吗?
您可以发布完整例外,包括堆栈跟踪吗? – svick