從asp.net中的web服務器下載文件c＃到客戶端的電腦

Question

我想從服務器下載一個文件到客戶端選擇到他們的機器上的文件夾。不過，我不斷收到錯誤could not find part of the path

例如，DownloadLocation可能是C：/ MyFolder文件

代碼：

FileName = comp.DownloadLocation + "/" + "/purchase" + ".csv"; 
regularfilename = "purchase.csv"; 
byte[] buffer; 
using (FileStream fileStream = new FileStream(FileName, FileMode.Open)) 
{ 
    int fileSize = (int)fileStream.Length; 
    buffer = new byte[fileSize]; 
    fileStream.Read(buffer, 0, (int)fileSize); 
} 

Response.Clear(); 
Response.Buffer = true; 
Response.BufferOutput = true; 
Response.ContentType = "application/x-download"; 
Response.AddHeader("Content-Disposition", "attachment; filename=" + regularfilename); 
Response.CacheControl = "public"; 
Response.OutputStream.Write(buffer, 0, buffer.Length); 
Response.Flush(); 
Response.Clear(); 
Response.End(); 

Answer 1

可能不是問題的答案然而這東西你一定要檢查：

FileName = comp.DownloadLocation + "/" + "/purchase" + ".csv"; 

您可能希望在購買之前刪除/或完全刪除+「/」+，因爲這樣會以格式生成路徑：

「somepath // purchase.csv」

可能會引發您的問題。看看它是否有所作爲。

Answer 2

如果你需要一個客戶端應用程序來檢查Web API服務器，看看服務器的文件的版本比客戶端版本更新，您可以設置服務器，通過執行以下步驟來完成：

添加適當的方法來存儲庫接口，如：

HttpResponseMessage GetCervezaBeberUpdate(string clientVersion); 

此添加到相應的控制器類（其中，控制器名稱是「HenryFieldingController」）：

[Route("api/HenryFielding/GetUpdatedCervezaBeber")] 
public HttpResponseMessage GetUpdate(string clientVersion) 
{ 
    return _tomJonesRepository.GetCervezaBeberUpdate(clientVersion); 
} 

添加適當的方法來具體的庫類，如：

public HttpResponseMessage GetCervezaBeberUpdate(string clientVersion) 
{ 
    var binaryFilePath = HostingEnvironment.MapPath(@"~\App_Data\CervezaBeber.exe"); 
    FileVersionInfo currentVersion = FileVersionInfo.GetVersionInfo(binaryFilePath); 
    if (!ServerFileIsNewer(clientVersion, currentVersion)) 
    { 
     result = new HttpResponseMessage(HttpStatusCode.NoContent); 
    } 
    else 
    { 
     var stream = new FileStream(binaryFilePath, FileMode.Open); 
     HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK); 
     result.Content = new StreamContent(stream); 
     result.Content.Headers.ContentType = 
      new MediaTypeHeaderValue("application/octet-stream"); 
    } 
    return result; 
} 

還要添加方法在庫類GetCervezaBeberUpdate（）調用：

private bool ServerFileIsNewer(string clientFileVersion, FileVersionInfo serverFile) 
{ 
    Version client = new Version(clientFileVersion); 
    Version server = new Version(string.Format("{0}.{1}.{2}.{3}", serverFile.FileMajorPart, serverFile.FileMinorPart, serverFile.FileBuildPart, serverFile.FilePrivatePart)); 
    return server > client; 
} 

現在，客戶可以通過撥打該傳遞一個URI這樣對服務器：

http://<servername>:<portnumber>/api/ 
<controllername>?clientVersion=<clientversionquad> 

或者，更字面例如，在事件服務器的名稱爲「鴨嘴獸」，使用的端口是424 2，該控制器被命名爲HenryFieldingController，並且客戶端目前有文件的版本是3.1.4.1：

http://Platypus:4242/api/HenryFielding?clientVersion=3.1.4.1 

爲自由的，在啤酒（你/我的心願！）溢價，這裏的一些代碼客戶端可以使用服務器的響應保存到文件（通過這一個URI如上面所示）：

private void DownloadTheFile(string uri) 
{ 
    var outputFileName = "Platypus.exe"; 
    var webRequest = (HttpWebRequest)WebRequest.Create(uri); 
    var webResponse = (HttpWebResponse)webRequest.GetResponse(); 
    string statusCode = webResponse.StatusCode.ToString(); 
    // From here on (including the CopyStream() method) derived from Jon Skeet's 
    // answer at http://stackoverflow.com/questions/411592/how-do-i-save-a-stream-to-a-file 
    if (statusCode == "NoContent") 
    { 
     MessageBox.Show("You already have the newest available version."); 
    } 
    else 
    { 
     var responseStream = webResponse.GetResponseStream(); 
     using (Stream file = File.Create(outputFileName)) 
     { 
      CopyStream(responseStream, file); 
      MessageBox.Show(string.Format("New version downloaded to {0}", outputFileName)); 
     } 
    } 
} 

public static void CopyStream(Stream input, Stream output) 
{ 
    byte[] buffer = new byte[8 * 1024]; 
    int len; 
    while ((len = input.Read(buffer, 0, buffer.Length)) > 0) 
    { 
     output.Write(buffer, 0, len); 
    } 
}