我可以在迭代器块内创建下载进度条吗？

Question

我知道进度条本身已经被要求死亡，但我遇到了麻烦。我需要通过FTP下载文件，我使用WebClient，下载的数据必须保存到字节数组中，但WebClient.DownloadDataAsync不能直接返回，所以我必须使用DownloadDataCompleted方法来访问数据。一切都没问题，但问题是我不能“暂停”IEnumerator块而没有阻塞整个线程，如果我不暂停它，应用程序崩溃，因为它的字节数组不存在试图访问它。当要下载的文件在http中时，我使用了WWW并没有任何问题，但必须将其移至FTP。使用WebClient.DownloadData的作品，但我被要求包括一个进度条。总之，here's代码：

IEnumerator DownloadGame(Dictionary<string, string> settingsDict) 
    { 
     statusText = "Starting download..."; 
     WebClient request = new WebClient(); 
     request.Credentials = new NetworkCredential("user", "password"); 
     request.DownloadDataCompleted += DownloadDataCompleted; 

     //byte[] fileData = request.DownloadData(settingsDict["downloadlink"]); This works, but is no good since it blocks the thread 
    request.DownloadDataAsync(new Uri(settingsDict["downloadlink"]),"somefilepath"); 


    //do{}while(!downloadFinished); This also works but blocks the thread anyway 


    //Process the update 
    string tmpRoot = TMPFolder(); 
    string tmpFolder = tmpRoot + Application.platform + settingsDict["latestVersion"] + "/"; 
    if (!UnzipUpdate(fileData, tmpFolder))//fail here, in this case fileData is global 
    { 
     DeleteDirectory(tmpRoot); 
     yield break; 
    } 
    if (!ProcessUpdateData(tmpFolder)) 
    { 
     DeleteDirectory(tmpRoot); 
     yield break; 
    } 
    DeleteDirectory(tmpRoot); 

    settingsDict["thisVersion"] = GetNextVersion(); 
} 

void DownloadDataCompleted(object sender, DownloadDataCompletedEventArgs e){ 

    fileData = e.Result; 
    downloadFinished = true; 
} 

Answer 1

你可以使用像这样基于以前Stakoverflow后..

最简单的方法是使用BackgroundWorker，把你的代码放到DoWork事件处理程序。并用BackgroundWorker.ReportProgress报告进度。

的基本思想：

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) 
{ 
    var ftpWebRequest = (FtpWebRequest)WebRequest.Create("ftp://xxx.com"); 
    ftpWebRequest.Method = WebRequestMethods.Ftp.UploadFile; //or DownLoad 
    using (var inputStream = File.OpenRead(fileName)) 
    using (var outputStream = ftpWebRequest.GetRequestStream()) 
    { 
     var buffer = new byte[1024 * 1024]; 
     int totalReadBytesCount = 0; 
     int readBytesCount; 
     while ((readBytesCount = inputStream.Read(buffer, 0, buffer.Length)) > 0) 
     { 
      outputStream.Write(buffer, 0, readBytesCount); 
      totalReadBytesCount += readBytesCount; 
      var progress = totalReadBytesCount * 100.0/inputStream.Length; 
      backgroundWorker1.ReportProgress((int)progress); 
     } 
    } 
} 

private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e) 
{ 
    progressBar.Value = e.ProgressPercentage; 
} 

确保WorkerReportsProgress启用

backgroundWorker2.WorkerReportsProgress = true; 

随着BackgroundWorker你也可以轻松实现上传取消。