爲什麼我的WebClient上傳文件代碼掛起？

Question

我使用VSTS 2008 + C＃+ .Net 3.5 + ASP.Net + IIS 7.0在客戶端開發Windows Forms應用程序以上載文件，而在服務器端，我使用aspx文件接收此文件。

我發現我的客戶端應用程序會在點擊按鈕觸發上傳事件後掛起。任何想法什麼是錯的，以及如何解決？謝謝！

客戶端代碼，

public partial class Form1 : Form 
    { 
     private static WebClient client = new WebClient(); 
     private static ManualResetEvent uploadLock = new ManualResetEvent(false); 

     private static void Upload() 
     { 
      try 
      { 
       Uri uri = new Uri("http://localhost/Default2.aspx"); 
       String filename = @"C:\Test\1.dat"; 

       client.Headers.Add("UserAgent", "TestAgent"); 
       client.UploadProgressChanged += new UploadProgressChangedEventHandler(UploadProgressCallback); 
       client.UploadFileCompleted += new UploadFileCompletedEventHandler(UploadFileCompleteCallback); 
       client.UploadFileAsync(uri, "POST", filename); 
       uploadLock.WaitOne(); 
      } 
      catch (Exception e) 
      { 
       Console.WriteLine(e.StackTrace.ToString()); 
      } 
     } 

     public static void UploadFileCompleteCallback(object sender, UploadFileCompletedEventArgs e) 
     { 
      Console.WriteLine("Completed! "); 
      uploadLock.Set(); 
     } 

     private static void UploadProgressCallback(object sender, UploadProgressChangedEventArgs e) 
     { 
      Console.WriteLine("{0} uploaded {1} of {2} bytes. {3} % complete...", 
       (string)e.UserState, 
       e.BytesSent, 
       e.TotalBytesToSend, 
       e.ProgressPercentage); 

      // Console.WriteLine (e.ProgressPercentage); 
     } 

     public Form1() 
     { 
      InitializeComponent(); 
     } 

     private void button1_Click(object sender, EventArgs e) 
     { 
      Upload(); 
     } 
    } 

服務器端代碼：

protected void Page_Load(object sender, EventArgs e) 
    { 
     string agent = HttpContext.Current.Request.Headers["UserAgent"]; 
     using (FileStream file = new FileStream(@"C:\Test\Agent.txt", FileMode.Append, FileAccess.Write)) 
     { 
      byte[] buf = Encoding.UTF8.GetBytes(agent); 
      file.Write(buf, 0, buf.Length); 
     } 

     foreach (string f in Request.Files.AllKeys) 
     { 
      HttpPostedFile file = Request.Files[f]; 
      file.SaveAs("C:\\Test\\UploadFile.dat"); 
     } 
    } 

Answer 1

你正在等待在主窗口的事件線程，因此您的GUI將被凍結。

試試這個（使用非靜態方法允許你使用Control.Invoke方法，以重繪運行Windows GUI線程和免費這個線程上回調）

public partial class Form1 : Form 
{ 
    private static WebClient client = new WebClient(); 
    private static ManualResetEvent uploadLock = new ManualResetEvent(false); 

    private void Upload() 
    { 
     try 
     { 
      Cursor=Cursors.Wait; 
      Uri uri = new Uri("http://localhost/Default2.aspx"); 
      String filename = @"C:\Test\1.dat"; 

      client.Headers.Add("UserAgent", "TestAgent"); 
      client.UploadProgressChanged += new UploadProgressChangedEventHandler(UploadProgressCallback); 
      client.UploadFileCompleted += new UploadFileCompletedEventHandler(UploadFileCompleteCallback); 
      client.UploadFileAsync(uri, "POST", filename);  
     } 
     catch (Exception e) 
     { 
      Console.WriteLine(e.StackTrace.ToString()); 
      this.Cursor=Cursors.Default; 
      this.Enabled=false; 
     } 
    } 

    public void UploadFileCompleteCallback(object sender, UploadFileCompletedEventArgs e) 
    { 
     // this callback will be invoked by the async upload handler on a ThreadPool thread, so we cannot touch anything GUI-related. For this we have to switch to the GUI thread using control.BeginInvoke 
     if(this.InvokeRequired) 
     { 
      // so this is called in the main GUI thread 
      this.BeginInvoke(new UploadFileCompletedEventHandler(UploadFileCompleteCallback); // beginInvoke frees up the threadpool thread faster. Invoke would wait for completion of the callback before returning. 
     } 
     else 
     { 
      Cursor=Cursors.Default; 
      this.enabled=true; 
      MessageBox.Show(this,"Upload done","Done"); 
     } 
public Form1() 
     { 
      InitializeComponent(); 
     } 

     private void button1_Click(object sender, EventArgs e) 
     { 
      Upload(); 
     } 
    } 
} 

，做同樣的事情在您的進度（例如，您可以更新進度條指示符）。

乾杯， 弗洛裏安