是否WebClient.OpenFileAsync火DownloadProgressChanged

问题描述

据

的,

OpenFileAsync应该DownloadProgressChanged射击时，它使人进步。

OpenFileAsync should have DownloadProgressChanged firing whenever it makes progress.

我不能让它火的。火灾罚款DownloadDataAsync和DownloadFileAsync反而虽然。

I can't get it to fire at all. Fires fine with DownloadDataAsync and DownloadFileAsync instead though.

下面是一个简单的例子：

Here's a simple example:

using System;
using System.Net;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            WebClient client = new WebClient();
            client.OpenReadCompleted += new OpenReadCompletedEventHandler(client_OpenReadCompleted);
            client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(client_DownloadProgressChanged);
            client.OpenReadAsync(new Uri("http://www.stackoverflow.com"));
            Console.ReadKey();
        }

        static void client_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
        {
            Console.WriteLine("{0}% Downloaded", e.ProgressPercentage);
        }

        static void client_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
        {
            Console.WriteLine("Open Read Completed");
        }
    }
}

有关我的DownloadProgressChanged事件永远不会触发，但变化DownloadFileAsync或DownloadDataAsync和它的作用。

For me the DownloadProgressChanged event never fires, although change to DownloadFileAsync or DownloadDataAsync and it does.

推荐答案

我看过的框架来源，据我可以告诉OpenReadAsync从来没有触及触发DownloadProgressChanged的东西。

I've looked at the framework source and as far as I can tell the OpenReadAsync never touches the stuff that triggers DownloadProgressChanged.

这不叫喜欢DownloadDataAsync和DownloadFileAsync做，而这又似乎什么被拉开活动的GetBytes。

It doesn't call GetBytes like DownloadDataAsync and DownloadFileAsync do, which is what in turn appears to be kicking off the event.

要解决它，我只是用DownloadDataAsync代替，这确实触发事件，并让我提供下载的UI反馈。它返回一个字节数组，而不是我所需要的数据流，但是这不是一个问题。

To work around it I've just used DownloadDataAsync instead, which does trigger the event and allows me to provide UI feedback for the download. It returns a byte array instead of the stream I needed, but that's not an issue.

所以我假定这是MSDN那是错在这里，和OpenReadAsync不会触发DownloadProgressChanged。

So I'm assuming that it's MSDN that's wrong here, and OpenReadAsync doesn't trigger DownloadProgressChanged.

这篇关于是否WebClient.OpenFileAsync火DownloadProgressChanged的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！