未调用 UploadProgressChanged 事件答案

【问题标题】：UploadProgressChanged Event Not Being Called未调用 UploadProgressChanged 事件
【发布时间】：2012-12-04 06:02:37
【问题描述】：

我正在使用如下所示的 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，UploadProgressChanged 事件处理程序从未被调用。

有什么想法吗？

【问题讨论】：

标签： c# file-upload uri

【解决方案1】：

变化：

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

为：

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

您正在绑定事件在 UploadFileAsync 调用之后，您必须绑定事件处理程序首先。

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.");
}

【讨论】：

当 UploadFileCompletedEventHandler 触发时，它是上传到目标目标的文件吗？

【解决方案2】：

您应该首先添加 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);

【讨论】：

试过了，进度改变事件仍然没有被调用。
您确定上传有效吗？上传后是否在服务器上获取文件？