無法下載文件到AppData文件夾

Question

即時通訊嘗試編寫一些代碼，下載文件並將其保存在AppData中，但由於某種原因，我在DownloadFile()調用期間不斷收到異常。

例外：

類型 'System.Net.WebException' 的未處理的異常發生在 System.dll中

其他信息：一個Web客戶端 請求期間發生異常。

這裏是我的代碼：

string remoteUri = "http://mhost.site11.com/"; 
      string fileName = "SysSpec.zip", myStringWebResource = null; 

      string appData = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData); 

      // Create a new WebClient instance. 
      using (WebClient myWebClient = new WebClient()) 
      { 
       try 
       { 
        myStringWebResource = remoteUri + fileName; 
        // Download the Web resource and save it into the current filesystem folder. 
        myWebClient.DownloadFile(myStringWebResource, appData + "\\PPA\\" + fileName); 
       } 
       catch (WebException er) 
       { 
        var result = GetResponceFromWebException(er); 
        if (result != null) 
        { 
         MessageBox.Show(result.ToString()); 
        } 

        throw; 
       } 
       catch (Exception er) 
       { 
        MessageBox.Show(er.ToString());  
       } 
      } 
     } 
     private HttpRequestResponce GetResponceFromWebException(WebException e) 
     { 
      HttpRequestResponce result = null; 
      if (e.Status == WebExceptionStatus.ProtocolError) 
      { 
       try 
       { 
        using (var stream = e.Response.GetResponseStream()) 
        { 
         if (stream != null) 
         { 
          using (var reader = new StreamReader(stream)) 
          { 
           var responseString = reader.ReadToEnd(); 
           var responce = ((HttpWebResponse)e.Response); 

           result = new HttpRequestResponce(responseString, responce.StatusCode); 
          } 
         } 
        } 
       } 
       catch (Exception ex) 
       { 
        // log exception or do nothing or throw it 
       } 
      } 
      return result; 
     } 

---

解決方案：

將文件下載到該目錄我的計劃是在第一，然後移動它。

string remoteUri = "http://mhost.site11.com/"; 
      string fileName = "SysSpec.zip", myStringWebResource = null; 

      string appData = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData); 

      // Create a new WebClient instance. 
      using (WebClient myWebClient = new WebClient()) 
      { 
       myStringWebResource = remoteUri + fileName; 
       // Download the Web resource and save it into the current filesystem folder. 
       myWebClient.DownloadFile(myStringWebResource, fileName); 

       // Move the file 
       string path = fileName; 
       string path2 = appData + "\\PPA\\" + fileName; 

       try 
       { 
        if (!File.Exists(path)) 
        { 
         // This statement ensures that the file is created, 
         // but the handle is not kept. 
         using (FileStream fs = File.Create(path)) { } 
        } 

        // Ensure that the target does not exist. 
        if (File.Exists(path2)) 
         File.Delete(path2); 

        // Move the file. 
        File.Move(path, path2); 
       } 
       catch (Exception er) 
       { 
        Console.WriteLine("The process failed: {0}", er.ToString()); 
       } 
      } 
     } 

Answer 1

您可能會遇到寫入該文件夾的權限問題。檢查您的進程是否具有AppData文件夾的寫入權限。如果您使用IIS，則必須允許的用戶的格式爲IIS AppPool\DefaultAppPool，您必須將DefaultAppPool替換爲您的應用程序池名稱。