wb.DownloadFileAsync throw "WebClientは同時I/O操作をサポートしていません。例外

Question

は、私はあなたがそれを再度ダウンロードしようとする前に完了したことを確認する必要がありDownloadFileAsyncメソッドを呼び出す場合、このコード

#region Events 

public class DownloadProgressChangedEventArg 
{ 
    private long _ProgressPercentage; 
    private long _BytesReceived; 
    private long _TotalBytesToReceive; 

    public DownloadProgressChangedEventArg(long BytesReceived, long TotalBytesToReceive) 
    { 
     _BytesReceived = BytesReceived; 
     _TotalBytesToReceive = TotalBytesToReceive; 
     _ProgressPercentage = BytesReceived * 100/(TotalBytesToReceive); 
    } 

    public long BytesReceived { get { return _BytesReceived; } set { _BytesReceived = value; } } 
    public long ProgressPercentage { get { return _ProgressPercentage; } set { _ProgressPercentage = value; } } 
    public long TotalBytesToReceive { get { return _TotalBytesToReceive; } set { _TotalBytesToReceive = value; } } 
} 

public delegate void DownloadProgressChangedEventHandler(Api.GetSong.GetObject.Object Sender, DownloadProgressChangedEventArg e); 
public event DownloadProgressChangedEventHandler DownloadProgressChangedEvent; 

public class DownloadCompletedEventArg 
{ 
    private bool _Cancelled; 
    private Exception _Error; 

    public DownloadCompletedEventArg(Exception Error, bool Cancelled) 
    { 
     _Cancelled = Cancelled; 
     _Error = Error; 
    } 

    public bool Cancelled { get { return _Cancelled; } set { _Cancelled = value; } } 
    public Exception Error { get { return _Error; } set { _Error = value; } } 

} 

public delegate void DownloadCompletedEventHandler(Api.GetSong.GetObject.Object Sender, DownloadCompletedEventArg e); 
public event DownloadCompletedEventHandler DownloadCompletedEvent; 

#endregion 

WebClient wb; 
public void DownloadFileAsync(Api.GetSong.GetObject.Object Object, String FileLocation) 
{ 
    String DownloadLink = GetStreamUri(Object); 
    String FileTitle = Object.Title + "." + Object.Type; 
    String FileLocations = Path.Combine(FileLocation,FileTitle); 

    if (!DownloadLink.StartsWith("rtmp")) 
    { 
     if (wb == null) 
     { 
      wb = new WebClient(); 
      wb.DownloadFileCompleted += delegate(object sender, AsyncCompletedEventArgs e) { DownloadCompletedEvent(Object, new DownloadCompletedEventArg(e.Error, e.Cancelled)); }; 
      wb.DownloadProgressChanged += delegate(object sender, DownloadProgressChangedEventArgs e) { DownloadProgressChangedEvent(Object, new DownloadProgressChangedEventArg(e.BytesReceived, e.TotalBytesToReceive)); }; 
     } 
     wb.DownloadFileAsync(new Uri(DownloadLink), FileLocations); 

     //throw: 
     //WebClient does not support concurrent I/O operations. 

    } 
    else 
    { 
     //Düzenlencek 
    } 
} 

public void DownloadFileCancel() 
{ 
    if (wb.IsBusy && wb != null) 
    { 
     wb.CancelAsync(); 
    } 
} 

Answer 1

を支援する必要があります。

This answerがお手伝いします。