下面是 ASP.NET WebAPi(selfhost)实现文件同步或异步上传的完整攻略。
概述
ASP.NET WebAPI 是一种基于 HTTP 协议构建 Web Service 的框架,它可以轻松地将你的 .NET 应用程序转换成 Web 服务。在这里,我们将使用 ASP.NET WebAPI 实现文件的同步或异步上传。
实现步骤
-
首先,我们需要在 Visual Studio 中创建一个 ASP.NET WebAPI 项目,并在
NuGet
包管理器中安装Microsoft.AspNet.WebApi.SelfHost
包。 -
接着,在项目中创建一个
FileController
控制器,并添加以下方法:
public async Task<HttpResponseMessage> PostFile()
{
var response = new HttpResponseMessage();
if (!Request.Content.IsMimeMultipartContent())
{
response.StatusCode = HttpStatusCode.UnsupportedMediaType;
response.Content = new StringContent("Unsupported Media Type");
throw new HttpResponseException(response);
}
var provider = new MultipartFileStreamProvider();
await Request.Content.ReadAsMultipartAsync(provider);
foreach (var file in provider.FileData)
{
var fileName = file.Headers.ContentDisposition.FileName.Trim('\"');
var localFilePath = Path.Combine(@"D:\FileUploads", fileName);
if (File.Exists(localFilePath))
{
File.Delete(localFilePath);
}
File.Move(file.LocalFileName, localFilePath);
}
response.StatusCode = HttpStatusCode.OK;
response.Content = new StringContent("File uploaded successfully");
return response;
}
-
上述方法中,我们使用了
MultipartFileStreamProvider
来读取并处理 HTTP 请求中的数据。接下来的代码块遍历了每一个上传的文件,将其保存在本地。 -
方法中的
PostFile
标记了async
关键字。这样做是因为 WebAPI 是通过 HTTP 与客户端通信的,而 HTTP 通信是 I/O 操作,有可能会耗费很长时间。因此,在需要大量 I/O 操作时,我们应该使用异步调用以避免阻塞线程。 -
随着上传文件的大小或数量的增加,同步的文件上传可能会变得非常缓慢,并且可能会导致超时。为了解决这个问题,我们可以使用异步操作,例如:
public async Task<HttpResponseMessage> UploadAsync()
{
try
{
var filesReadToProvider = await Request.Content.ReadAsMultipartAsync();
var streamProviders = new List<Task<FileResult>>();
foreach (var file in filesReadToProvider.FileData)
{
streamProviders.Add(StoreFileAsync(file));
}
return await Task.Factory.ContinueWhenAll(streamProviders.ToArray(), results =>
{
var response = new HttpResponseMessage(HttpStatusCode.OK)
{
Content = new StringContent("Files uploaded successfully")
};
return response;
});
}
catch (Exception ex)
{
return new HttpResponseMessage(HttpStatusCode.InternalServerError)
{
Content = new StringContent(ex.Message)
};
}
}
private async Task<FileResult> StoreFileAsync(MultipartFileData fileData)
{
var fileName = fileData.Headers.ContentDisposition.FileName.Trim('\"');
var localFilePath = Path.Combine(@"D:\FileUploads", fileName);
if (File.Exists(localFilePath))
{
File.Delete(localFilePath);
}
File.Move(fileData.LocalFileName, localFilePath);
return new FileResult
{
FileName = fileName,
FilePath = localFilePath
};
}
public class FileResult
{
public string FileName { get; set; }
public string FilePath { get; set; }
}
-
上述代码中,我们首先使用
async
方法处理 HTTP 请求,并异步获取所有的文件。接着,我们定义了一个名为StreamProviders
的Task
列表,并遍历每个文件,将其异步上传。 -
在
StoreFileAsync
方法中,我们从fileData
对象中获取文件名,以及写入到本地磁盘的路径。使用File
类的Move
方法将文件移动到本地文件系统,并创建一个FileResult
对象表示文件的元数据。 -
最后,我们调用
Task.Factory.ContinueWhenAll
方法等待所有上传完成的文件,然后返回包含所有上传文件的信息的HttpResponseMessage
对象。
示例说明
示例 1
下面是一个简单的同步文件上传的示例。
客户端代码
using (var httpClient = new HttpClient())
{
using (var formData = new MultipartFormDataContent())
{
using (var fileContent = new ByteArrayContent(File.ReadAllBytes("D:\\Test.txt")))
{
formData.Add(fileContent, "file", "Test.txt");
var response = await httpClient.PostAsync("http://localhost:8080/api/File/PostFile", formData);
if (response.IsSuccessStatusCode)
{
Console.WriteLine("File uploaded successfully");
}
}
}
}
服务器端代码
public async Task<HttpResponseMessage> PostFile()
{
var response = new HttpResponseMessage();
if (!Request.Content.IsMimeMultipartContent())
{
response.StatusCode = HttpStatusCode.UnsupportedMediaType;
response.Content = new StringContent("Unsupported Media Type");
throw new HttpResponseException(response);
}
var provider = new MultipartFileStreamProvider();
await Request.Content.ReadAsMultipartAsync(provider);
foreach (var file in provider.FileData)
{
var fileName = file.Headers.ContentDisposition.FileName.Trim('\"');
var localFilePath = Path.Combine(@"D:\FileUploads", fileName);
if (File.Exists(localFilePath))
{
File.Delete(localFilePath);
}
File.Move(file.LocalFileName, localFilePath);
}
response.StatusCode = HttpStatusCode.OK;
response.Content = new StringContent("File uploaded successfully");
return response;
}
示例 2
下面是一个异步文件上传的示例。
客户端代码
using (var httpClient = new HttpClient())
{
using (var formData = new MultipartFormDataContent())
{
using (var fileContent = new ByteArrayContent(File.ReadAllBytes("D:\\Test.txt")))
{
formData.Add(fileContent, "file", "Test.txt");
var response = await httpClient.PostAsync("http://localhost:8080/api/File/UploadAsync", formData);
if (response.IsSuccessStatusCode)
{
Console.WriteLine(await response.Content.ReadAsStringAsync());
}
}
}
}
服务器端代码
public async Task<HttpResponseMessage> UploadAsync()
{
try
{
var filesReadToProvider = await Request.Content.ReadAsMultipartAsync();
var streamProviders = new List<Task<FileResult>>();
foreach (var file in filesReadToProvider.FileData)
{
streamProviders.Add(StoreFileAsync(file));
}
return await Task.Factory.ContinueWhenAll(streamProviders.ToArray(), results =>
{
var response = new HttpResponseMessage(HttpStatusCode.OK)
{
Content = new StringContent("Files uploaded successfully")
};
return response;
});
}
catch (Exception ex)
{
return new HttpResponseMessage(HttpStatusCode.InternalServerError)
{
Content = new StringContent(ex.Message)
};
}
}
private async Task<FileResult> StoreFileAsync(MultipartFileData fileData)
{
var fileName = fileData.Headers.ContentDisposition.FileName.Trim('\"');
var localFilePath = Path.Combine(@"D:\FileUploads", fileName);
if (File.Exists(localFilePath))
{
File.Delete(localFilePath);
}
File.Move(fileData.LocalFileName, localFilePath);
return new FileResult
{
FileName = fileName,
FilePath = localFilePath
};
}
public class FileResult
{
public string FileName { get; set; }
public string FilePath { get; set; }
}
以上就是 ASP.NET WebAPI(selfhost)实现文件同步或异步上传的完整攻略。
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