asp.net - MVC 6 WebAPI 返回序列化的 HttpResponseMessage 而不是文件流

Question

我正在尝试让我的 ASP.Net 5 MVC 6 WebAPI 项目输出一个文件，以响应 HttpGET 请求。

该文件来自 Azure 文件共享，但它可以是包含二进制文件的任何流。

在我看来，MVC 序列化响应对象，并返回结果 JSON，而不是返回响应对象本身。

这是我的 Controller 方法:

    [HttpGet]
    [Route("GetFile")]
    public HttpResponseMessage GetFile(string Username, string Password, string FullName)
    {

        var client = new AzureFilesClient.AzureFilesClient(Username, Password);
        Stream azureFileStream =  client.GetFileStream(FullName).Result;
        var fileName = Path.GetFileName(FullName);

        using (HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK))
        {
            response.Content = new StreamContent(azureFileStream);
            response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
            response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") { FileName = fileName };
            return response;
        }
    }

AzureFilesClient 上的 GetFileStream 方法位于此处，尽管流源可以是包含二进制文件内容的任何内容:

    public async Task<Stream> GetFileStream(string fileName)
    {
        var uri = new Uri(share.Uri + "/" + fileName);
        var file = new CloudFile(uri, credentials);

        using (var stream = new MemoryStream())
        {
            await file.DownloadToStreamAsync(stream);
            stream.Seek(0, SeekOrigin.Begin);
            return stream;
        }
    }

编辑:以下是 JSON 响应的示例:

{
    "Version": {
        "Major": 1,
        "Minor": 1,
        "Build": -1,
        "Revision": -1,
        "MajorRevision": -1,
        "MinorRevision": -1
    },
    "Content": {
        "Headers": [
            {
                "Key": "Content-Type",
                "Value": [
                    "application/octet-stream"
                ]
            },
            {
                "Key": "Content-Disposition",
                "Value": [
                    "attachmentx; filename=\"samplefile.docx\""
                ]
            }
        ]
    },
    "StatusCode": 200,
    "ReasonPhrase": "OK",
    "Headers": [],
    "RequestMessage": null,
    "IsSuccessStatusCode": true
}

Answer 1

经过阅读文档以及一些尝试和错误，问题已经解决。

Azure 部分是使用 nuGet 包“WindowsAzure.Storage”(4.4.1-预览版)制作的

首先是 JSON 序列化的输出。这需要返回自定义操作结果。

using Microsoft.AspNet.Mvc;
using System.IO;
using System.Threading.Tasks;

public class FileResultFromStream : ActionResult
{
    public FileResultFromStream(string fileDownloadName, Stream fileStream, string contentType)
    {
        FileDownloadName = fileDownloadName;
        FileStream = fileStream;
        ContentType = contentType;
    }

    public string ContentType { get; private set; }
    public string FileDownloadName { get; private set; }
    public Stream FileStream { get; private set; }

    public async override Task ExecuteResultAsync(ActionContext context)
    {
        var response = context.HttpContext.Response;
        response.ContentType = ContentType;
        context.HttpContext.Response.Headers.Add("Content-Disposition", new[] { "attachment; filename=" + FileDownloadName });
        await FileStream.CopyToAsync(context.HttpContext.Response.Body);
    }
}

现在获取从 Azure 文件共享(或任何其他异步流源)流式传输的二进制数据

using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Auth;
using Microsoft.WindowsAzure.Storage.File;
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Threading.Tasks;

    public async Task<Stream> GetFileStreamAsync(string fileName)
    {
        var uri = new Uri(share.Uri + "/" + fileName);
        var file = new CloudFile(uri, credentials);

        // Note: Do not wrap the stream variable in a Using, since it will close the stream too soon.
        var stream = new MemoryStream();
        await file.DownloadToStreamAsync(stream);
        stream.Seek(0, SeekOrigin.Begin);
        return stream;
    }

最后是 Controller 代码。请注意 IActionResult 接口(interface)的使用。

    [HttpGet]
    [Route("GetFile")]
    public async Task<IActionResult> GetFile(string username, string password, string fullName)
    {
        var client = new AzureFilesClient.AzureFilesClient(username, password);
        Stream stream = await client.GetFileStreamAsync(fullName);
        string fileName = Path.GetFileName(fullName);
        return new CustomActionResults.FileResultFromStream(fileName, stream, "application/msword");
    }

注意:此示例仅用于 Word 文件，您可能需要考虑将 ContentType 参数设为动态，而不是像这样的静态参数。