C# ActionResult 返回一个流
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ActionResult returning a Stream
提问by Nate Pet
My ActionResultreturns a Filebut I also need it to conditionally return a Stream.
我ActionResult返回 aFile但我也需要它有条件地返回 a Stream。
I have not been able to find documentation on how an ActionResultcan return a Stream.
我无法找到有关如何ActionResult返回Stream.
Here is my code for return of a file:
这是我返回文件的代码：
return File(memoryStream,.... )
As mentioned, I need to return just a Stream.
如前所述，我只需要返回一个Stream.
采纳答案by aifarfa
Updated for MVC5 2020:
为 MVC5 2020 更新：
my previous answer was dated.
我之前的回答已经过时了。
as of now, the Filereturns different type of ActionResult depends on given arguments
截至目前，File返回不同类型的 ActionResult 取决于给定的参数
// to return FileStreamResult
return File(memoryStream, "application/pdf");
// or..
return File(memoryStream, "application/pdf", "file_name");
Use FileStreamResult:
MemoryStream stream = someService.GetStream();
return new FileStreamResult(stream, "application/pdf")
回答by Darin Dimitrov
Having an action call another action is a design smell. You should avoid it. Simply put the logic that needs to be reused between the 2 actions in a service layer. And then call this logic from your 2 actions.
让一个动作调用另一个动作是一种设计味道。你应该避免它。简单的把需要重用的逻辑放在一个服务层的2个动作之间。然后从您的 2 个操作中调用此逻辑。
For example:
例如：
public ActionResult Action1()
{
Stream stream = service.GetStream();
// ... do something with the stream and return a view for example
return View();
}
public ActionResult Action2()
{
Stream stream = service.GetStream();
// let's return the stream to the client so that he could download it as file
return File(stream, "application/pdf");
}
Now you no longer need to call the second action from the first one.
现在您不再需要从第一个操作中调用第二个操作。
回答by Mark Amery
The shortest way to use a Streamas the result of an Action Method in a Controlleris the one you already showed in the question: use the Filehelper method of Controller. This returns a FileStreamResult.
将 aStream用作a中操作方法的结果的最短方法Controller是您在问题中已经展示的File方法：使用 的辅助方法Controller。这将返回一个FileStreamResult.
There are a couple of overloads available that take a Stream. Both overloads require the MIME type of the response to be specified, which will be emitted as the Content-Typeheader of the response; if your circumstances are such that this is unknown to your application, you could always specify text/plainor application/octet-streamfor arbitrary text or binary data, respectively. One overload additionally takes a third parameter that sets the filename to show in the browser's download dialogue (controlled via the Content-Dispositionheader), if applicable.
有几个可用的重载需要一个Stream. 两种重载都需要指定响应的 MIME 类型，该类型将作为Content-Type响应的标头发出；如果您的情况是您的应用程序未知，您可以始终分别指定text/plain或application/octet-stream任意文本或二进制数据。Content-Disposition如果适用，一个重载还采用第三个参数，用于设置文件名以显示在浏览器的下载对话框中（通过标题控制）。
Overload signatures:
重载签名：
protected internal FileStreamResult File(
Stream fileStream,
string contentType
)
and
和
protected internal virtual FileStreamResult File(
Stream fileStream,
string contentType,
string fileDownloadName
)
Example usage:
用法示例：
return File(myStream, "application/pdf");
or
或者
return File(myStream, "application/pdf", "billing-summary.pdf");
