Question

我有另一个问题:(。
我正在尝试为我的应用程序下载多个文件。

我的问题是：如何检查第一次下载是否已完成，然后继续第二次下载等等，我该怎么办？

这是我的代码atm：

        private void DownloadBukkit()
        {
            MySingleton.Instance.FirstStartProgress = "Downloading Bukkit.jar... Please stand by...";
            webClient.DownloadFileAsync(new Uri(MySingleton.Instance.BukkitDownloadLink), Jar_Location);
            webClient.DownloadProgressChanged += backgroundWorker1_ProgressChanged;
            webClient.DownloadFileCompleted += (webClient_DownloadFileCompleted);
        }

        private void DownloadDll()
        {
            if (!webClient.IsBusy)
            {
                MySingleton.Instance.FirstStartProgress = "Downloading HtmlAgilityPack.dll... Please stand by...";
                webClient2.DownloadFileAsync(new Uri(Dll_HtmlAgilityPackUrl), Dll_HtmlAgilityPackLocation);
                webClient2.DownloadProgressChanged += backgroundWorker1_ProgressChanged;
                webClient2.DownloadFileCompleted += (webClient2_DownloadFileCompleted);
            }
        }

    void webClient_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
    {
            DownloadDll();
    }


    void webClient2_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
    {
         Invoke((MethodInvoker)
               Close);
    }

    private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            Invoke((MethodInvoker)
                   delegate
                       {
                           labelProgress.Text = MySingleton.Instance.FirstStartProgress;
                           progressBar1.Value = e.ProgressPercentage;
                       });
        }

我已经检查了这个链接：DownloadFileAsync multiple files using webclient但我真的不明白如何植入这个:(。（我对C＃很新）

Answer 1

DownloadFileCompleted事件是您知道您已完成下载文件的信号。

来自MSDN：

每次异步文件下载操作时都会引发此事件的完成

从您的代码中可以看出，webClient和webClient2的声明位置和方式并不清楚，但实质上，您可以在触发第一个DownloadFileCompleted事件时开始第二次下载。但请注意，如果您使用WebClient的2个单独实例，则可以同时执行2个不同文件的下载。

Answer 2

以下是您可以根据自己的要求更改的快进代码。

 WebClient client = null;
        public FileDownloader()
        {
            InitializeComponent();
            client = new WebClient();
            client.DownloadProgressChanged += client_DownloadProgressChanged;
            client.DownloadFileCompleted += client_DownloadFileCompleted;
        }

        void client_DownloadFileCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
        {
            lblMessage.Text = "File Download Compeleted.";
        }

        void client_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
        {
            lblMessage.Text = e.ProgressPercentage + " % Downloaded.";
        }

        private void StartDownload(object sender, RoutedEventArgs e)
        {
            if (client == null)
                client = new WebClient();

//Loop thru your files for eg. file1.dll, file2.dll .......etc.
            for (int index = 0; index < 10; index++)
            {
                //loop on files 
                client.DownloadFileAsync(
                    new Uri(
                            @"http://mywebsite.com/Files/File" + index.ToString() + ".dll"
                            , UriKind.RelativeOrAbsolute),
                    @"C:\Temp\file+" + index.ToString() + ".dll");
            }

        }

C＃Webclient下载多个文件

2 个答案: