问题
我想在我的ASP中返回一个文件。Net Web API控制器，但我所有的方法返回HttpResponseMessage作为JSON。
目前为止的代码
public async Task<HttpResponseMessage> DownloadAsync(string id)
{
var response = new HttpResponseMessage(HttpStatusCode.OK);
response.Content = new StreamContent({{__insert_stream_here__}});
response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
return response;
}
当我在浏览器中调用这个端点时，Web API将HttpResponseMessage返回为JSON，并将HTTP内容报头设置为application/ JSON。
当前回答
ASP。NET 5 WEB API和Angular 12
您可以从服务器返回一个FileContentResult对象(Blob)。它不会被自动下载。你可以通过编程的方式在前端应用程序中创建一个锚标记，并将href属性设置为通过下面的方法从Blob创建的对象URL。现在点击锚点将下载文件。你也可以通过将“download”属性设置为锚来设置文件名。
downloadFile(path: string): Observable<any> {
return this._httpClient.post(`${environment.ApiRoot}/accountVerification/downloadFile`, { path: path }, {
observe: 'response',
responseType: 'blob'
});
}
saveFile(path: string, fileName: string): void {
this._accountApprovalsService.downloadFile(path).pipe(
take(1)
).subscribe((resp) => {
let downloadLink = document.createElement('a');
downloadLink.href = window.URL.createObjectURL(resp.body);
downloadLink.setAttribute('download', fileName);
document.body.appendChild(downloadLink);
downloadLink.click();
downloadLink.remove();
});
}
后端
[HttpPost]
[Authorize(Roles = "SystemAdmin, SystemUser")]
public async Task<IActionResult> DownloadFile(FilePath model)
{
if (ModelState.IsValid)
{
try
{
var fileName = System.IO.Path.GetFileName(model.Path);
var content = await System.IO.File.ReadAllBytesAsync(model.Path);
new FileExtensionContentTypeProvider()
.TryGetContentType(fileName, out string contentType);
return File(content, contentType, fileName);
}
catch
{
return BadRequest();
}
}
return BadRequest();
}
其他回答
下面是在.NET Core Web API中返回文件(例如图像文件)的基本示例:
<img src="@Url.Action("RenderImage", new { id = id})" alt="No Image found" />
下面是将文件从控制器返回到视图的代码。下面是Action方法，它将返回文件:
[Route("api/[controller]")]
public class DownloadController : Controller
{
//GET api/download/123
[HttpGet]
public async Task<IActionResult> RenderImage(string userId)
{
//get Image file using _fileservice from db
var result = await _fileService.getFile(userId);
if (result.byteStream == null)
return NotFound();
return File(result.byteStream, result.ContentType, result.FileName);
}
}
注意:
我们的文件应该首先转换为byte[]，然后在数据库中保存为varbinary(max)，以便检索。
ASP。NET 5 WEB API和Angular 12
您可以从服务器返回一个FileContentResult对象(Blob)。它不会被自动下载。你可以通过编程的方式在前端应用程序中创建一个锚标记，并将href属性设置为通过下面的方法从Blob创建的对象URL。现在点击锚点将下载文件。你也可以通过将“download”属性设置为锚来设置文件名。
downloadFile(path: string): Observable<any> {
return this._httpClient.post(`${environment.ApiRoot}/accountVerification/downloadFile`, { path: path }, {
observe: 'response',
responseType: 'blob'
});
}
saveFile(path: string, fileName: string): void {
this._accountApprovalsService.downloadFile(path).pipe(
take(1)
).subscribe((resp) => {
let downloadLink = document.createElement('a');
downloadLink.href = window.URL.createObjectURL(resp.body);
downloadLink.setAttribute('download', fileName);
document.body.appendChild(downloadLink);
downloadLink.click();
downloadLink.remove();
});
}
后端
[HttpPost]
[Authorize(Roles = "SystemAdmin, SystemUser")]
public async Task<IActionResult> DownloadFile(FilePath model)
{
if (ModelState.IsValid)
{
try
{
var fileName = System.IO.Path.GetFileName(model.Path);
var content = await System.IO.File.ReadAllBytesAsync(model.Path);
new FileExtensionContentTypeProvider()
.TryGetContentType(fileName, out string contentType);
return File(content, contentType, fileName);
}
catch
{
return BadRequest();
}
}
return BadRequest();
}
FileStreamResult为我工作。文件不是IActionResult。我不知道该怎么做。
你可以用这些方法返回FileResult:
1:返回FileStreamResult
[HttpGet("get-file-stream/{id}"]
public async Task<FileStreamResult> DownloadAsync(string id)
{
var fileName="myfileName.txt";
var mimeType="application/....";
Stream stream = await GetFileStreamById(id);
return new FileStreamResult(stream, mimeType)
{
FileDownloadName = fileName
};
}
2:返回FileContentResult
[HttpGet("get-file-content/{id}"]
public async Task<FileContentResult> DownloadAsync(string id)
{
var fileName="myfileName.txt";
var mimeType="application/....";
byte[] fileBytes = await GetFileBytesById(id);
return new FileContentResult(fileBytes, mimeType)
{
FileDownloadName = fileName
};
}
下面是一个简单的文件流示例:
using System.IO;
using Microsoft.AspNetCore.Mvc;
[HttpGet("{id}")]
public async Task<FileStreamResult> Download(int id)
{
var path = "<Get the file path using the ID>";
var stream = File.OpenRead(path);
return new FileStreamResult(stream, "application/octet-stream");
}
注意:
请确保使用来自Microsoft.AspNetCore.Mvc而不是System.Web.Mvc的FileStreamResult。
