Question

我正在使用下面显示的UploadFilesAsync方法上传文件。

var wc = new WebClient();
Uri myUri = new Uri(uriString);
wc.UploadFileAsync(myUri, "POST", filePath);
wc.UploadProgressChanged += new UploadProgressChangedEventHandler(wc_UploadProgressChanged);
wc.UploadFileCompleted += new UploadFileCompletedEventHandler(wc_UploadFileCompleted);

我的UploadFileCompleted事件处理程序被调用，但由于某种原因，从不调用UploadProgressChanged事件处理程序。

任何想法为什么？

Answer 1

变化：

wc.UploadFileAsync(myUri, "POST", filePath);
wc.UploadProgressChanged += new UploadProgressChangedEventHandler(wc_UploadProgressChanged);
wc.UploadFileCompleted += new UploadFileCompletedEventHandler(wc_UploadFileCompleted);

有关：

wc.UploadProgressChanged += new UploadProgressChangedEventHandler(wc_UploadProgressChanged);
wc.UploadFileCompleted += new UploadFileCompletedEventHandler(wc_UploadFileCompleted);
wc.UploadFileAsync(myUri, "POST", filePath);

您正在绑定事件 AFTER UploadFileAsync调用，您必须绑定事件处理程序第一

MSDN示例：

// Sample call: UploadFileInBackground2("http://www.contoso.com/fileUpload.aspx", "data.txt")
public static void UploadFileInBackground2 (string address, string fileName)
{
    WebClient client = new WebClient ();
    Uri uri = new Uri(address);

    client.UploadFileCompleted += new UploadFileCompletedEventHandler (UploadFileCallback2);

     // Specify a progress notification handler.
     client.UploadProgressChanged += new UploadProgressChangedEventHandler(UploadProgressCallback);
    client.UploadFileAsync (uri, "POST", fileName);
    Console.WriteLine ("File upload started.");
}

Answer 2

您应首先添加eventHandlers，然后调用将触发它们的方法。

wc.UploadProgressChanged += new UploadProgressChangedEventHandler(wc_UploadProgressChanged);
wc.UploadFileCompleted += new UploadFileCompletedEventHandler(wc_UploadFileCompleted);
wc.UploadFileAsync(myUri, "POST", filePath);

UploadProgressChanged事件未被调用

2 个答案: