我需要通过MVC操作方法传递文件。 从Web API方法下载并作为结果返回。
我所拥有的代码是根据SO和其他一些参考文献中的几个答案汇编而成的。
问题是当我尝试返回文件时，文件似乎被下载过程锁定。 我以为tsk.Wait（）会解决这个问题。
也许有人知道更好的解决方案？
using (var client = HttpClientProvider.GetHttpClient())
{
client.BaseAddress = new Uri(baseAddress);
await client.GetAsync("api/Documents/" + fileName).ContinueWith(
(requestTask) =>
{
HttpResponseMessage response = requestTask.Result;
response.EnsureSuccessStatusCode();
fileName = response.Content.Headers.ContentDisposition.FileName;
if (fileName.StartsWith("\"") && fileName.EndsWith("\""))
{
fileName = fileName.Trim('"');
}
if (fileName.Contains(@"/") || fileName.Contains(@"\"))
{
fileName = Path.GetFileName(fileName);
}
path = Path.Combine(GetDocsMapPath(), fileName);
System.Threading.Tasks.Task tsk = response.Content.ReadAsFileAsync(path, true).ContinueWith(
(readTask) =>
{
Process process = new Process();
process.StartInfo.FileName = path;
process.Start();
});
tsk.Wait();
HttpResponseMessage resp = new HttpResponseMessage(HttpStatusCode.OK);
resp.Content = new StreamContent(new FileStream(path, FileMode.Open, FileAccess.Read));
resp.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
resp.Content.Headers.ContentDisposition.FileName = fileName;
return resp;
});
}
public static Task ReadAsFileAsync(this HttpContent content, string filename, bool overwrite)
{
string pathname = Path.GetFullPath(filename);
if (!overwrite && File.Exists(filename))
{
throw new InvalidOperationException(string.Format("File {0} already exists.", pathname));
}
FileStream fileStream = null;
try
{
fileStream = new FileStream(pathname, FileMode.Create, FileAccess.Write, FileShare.None);
return content.CopyToAsync(fileStream).ContinueWith(
(copyTask) =>
{
fileStream.Close();
fileStream.Dispose();
});
}
catch
{
if (fileStream != null)
{
fileStream.Close();
fileStream.Dispose();
}
throw;
}
}
I have a requirement to pass a file through an MVC action method. To download it from a Web API method and return it as a result.
The code I have is assembled from a few answers here on SO and some other references.
The problem is that the file seems to be locked by the download process when I try to return it as a result. I thought that the tsk.Wait() wold solve the problem.
Perhaps someone knows of a better solution?
using (var client = HttpClientProvider.GetHttpClient())
{
client.BaseAddress = new Uri(baseAddress);
await client.GetAsync("api/Documents/" + fileName).ContinueWith(
(requestTask) =>
{
HttpResponseMessage response = requestTask.Result;
response.EnsureSuccessStatusCode();
fileName = response.Content.Headers.ContentDisposition.FileName;
if (fileName.StartsWith("\"") && fileName.EndsWith("\""))
{
fileName = fileName.Trim('"');
}
if (fileName.Contains(@"/") || fileName.Contains(@"\"))
{
fileName = Path.GetFileName(fileName);
}
path = Path.Combine(GetDocsMapPath(), fileName);
System.Threading.Tasks.Task tsk = response.Content.ReadAsFileAsync(path, true).ContinueWith(
(readTask) =>
{
Process process = new Process();
process.StartInfo.FileName = path;
process.Start();
});
tsk.Wait();
HttpResponseMessage resp = new HttpResponseMessage(HttpStatusCode.OK);
resp.Content = new StreamContent(new FileStream(path, FileMode.Open, FileAccess.Read));
resp.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
resp.Content.Headers.ContentDisposition.FileName = fileName;
return resp;
});
}
public static Task ReadAsFileAsync(this HttpContent content, string filename, bool overwrite)
{
string pathname = Path.GetFullPath(filename);
if (!overwrite && File.Exists(filename))
{
throw new InvalidOperationException(string.Format("File {0} already exists.", pathname));
}
FileStream fileStream = null;
try
{
fileStream = new FileStream(pathname, FileMode.Create, FileAccess.Write, FileShare.None);
return content.CopyToAsync(fileStream).ContinueWith(
(copyTask) =>
{
fileStream.Close();
fileStream.Dispose();
});
}
catch
{
if (fileStream != null)
{
fileStream.Close();
fileStream.Dispose();
}
throw;
}
}
最满意答案
首先，除了锁定您不想要的文件之外，我没有看到您启动的过程实现的任何有用功能。
尝试删除这些行并重试。
.ContinueWith(
(readTask) =>
{
Process process = new Process();
process.StartInfo.FileName = path;
process.Start();
});
编辑：使用FilePathResult
我不知道您的确切要求，但如果您的目标是返回一个您有路径的文件; 那么最简单的方法是返回一个FilePathResult，它将负责读取并将文件内容返回给请求者。
public FilePathResult GetFile()
{
//put your logic to determine the file path here
string name = ComputeFilePath();
//verify that the file actually exists and retur dummy content otherwise
FileInfo info = new FileInfo(name);
if (!info.Exists)
{
using (StreamWriter writer = info.CreateText())
{
writer.WriteLine("File Not Found");
}
}
return File(name, "application/octet-stream");
}
如果您确定内容的类型，请相应地更改mime类型，否则最好将其保留为二进制数据。
first, I don't see any useful function achieved by the process you launch, apart from locking your file, which you don't want.
try removing these lines and retrying.
.ContinueWith(
(readTask) =>
{
Process process = new Process();
process.StartInfo.FileName = path;
process.Start();
});
Edit: Using FilePathResult
I don't know about your exact requirements, but if your goal is to return a file that you have the path for; then the easiest is to return a FilePathResult which will take care of reading and returning the contents of the file to the requester.
public FilePathResult GetFile()
{
//put your logic to determine the file path here
string name = ComputeFilePath();
//verify that the file actually exists and retur dummy content otherwise
FileInfo info = new FileInfo(name);
if (!info.Exists)
{
using (StreamWriter writer = info.CreateText())
{
writer.WriteLine("File Not Found");
}
}
return File(name, "application/octet-stream");
}
if you are sure of what type your content is , change the mime type accordingly, otherwise it's better to leave it as a binary data.
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