Question

我正在使用Visual Studio中的WPF应用程序，我需要下载一个大文件并在我的代码中提取它。有人建议我使用后台工作人员，但现在当我尝试增加进度条上的值时，它不起作用......有人可以帮忙吗？

public void InstallVersion(string version)
    {
        string location = File.ReadAllText(@"C:\Users\" + Environment.UserName + @"\AppData\Roaming\MidnightFallsLauncher\data\locator.txt");
        location = location + @"\Versions\" + version;

        if (File.Exists(location + ".zip"))
            File.Delete(location + ".zip");

        if (Directory.Exists(location))
        {
            DirectoryInfo di = new DirectoryInfo(location);

            foreach (FileInfo file in di.GetFiles())
            {
                file.Delete();
            }
            foreach (DirectoryInfo dir in di.GetDirectories())
            {
                dir.Delete(true);
             }
        }


        if (!myWorker.IsBusy)
        {
            myWorker.RunWorkerAsync();
        }
    }

这是我的工人代码

public MainWindow()
    {
        InitializeComponent();

        myWorker.DoWork += new DoWorkEventHandler(myWorker_DoWork);
        myWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(myWorker_RunWorkerCompleted);
        myWorker.ProgressChanged += new ProgressChangedEventHandler(myWorker_ProgressChanged);
        myWorker.WorkerReportsProgress = true;
        myWorker.WorkerSupportsCancellation = true;
    }

    protected void myWorker_DoWork(object sender, DoWorkEventArgs e)
    {

        string location = File.ReadAllText(@"C:\Users\" + Environment.UserName + @"\AppData\Roaming\MidnightFallsLauncher\data\locator.txt");
        location = location + @"\Versions\" + Version;

        WebClient Client = new WebClient();
        string url = "";
        string content = "";
        string downloadlink = "";

        List<string> availibleVersions = new List<string>();
        List<string> versionDownload = new List<string>();

        url = "https://midnightfalls.glitch.me/versions.html";
        content = Client.DownloadString(url);

        foreach (string line in content.Split(new string[] { "<br>", "<br />" }, StringSplitOptions.None))
        {
            if (line.Contains("0"))
            {
                availibleVersions.Add(line);
            }

        }

        url = "https://midnightfalls.glitch.me/versionslink.html";
        content = Client.DownloadString(url);

        foreach (string line in content.Split(new string[] { "<br>", "<br />" }, StringSplitOptions.None))
        {
            if (line.Contains("https"))
            {
                versionDownload.Add(line);
            }

        }

        for (var i = 0; i < availibleVersions.Count; i++)
        {
            if (availibleVersions[i] == Version)
            {
                downloadlink = versionDownload[i];
            }
        }


        Client.DownloadFile(downloadlink, location + ".zip");

        ZipFile.ExtractToDirectory(location + ".zip", location);
        File.Delete(location + ".zip");

        RunGame(Version);
    }

    protected void myWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {

    }

    protected void myWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        this.Dispatcher.Invoke(() =>
        {
            progress.Value += 10;
        });
    }

此外，当我的工作人员正在运行时，用户界面冻结......我非常确定这不会发生。

修改用户界面现在正在更新，但进度条仍无效...

Answer 1

我很确定你在这里阻止：

while (this.myWorker.IsBusy)
{
    this.Dispatcher.Invoke(() =>
    {
        progress.Value += 10;
    });
}

您应该在ReportProgress方法中的BackgroundWorker个实例上致电myWorker_DoWork。

此外，如果您使用的是.NET 4.5或更高版本，则可以完全转储BackgroundWorker并使用async / await模式重写此代码。

Answer 2

看起来问题是主要线程在后台工作者正在工作时不断工作：

 while (this.myWorker.IsBusy)
 {
    this.Dispatcher.Invoke(() =>
    {
        progress.Value += 10;
    });
}

表示您的主线程在后台作业正在工作时不断地执行操作，这就是UI无法更新的原因。

您需要将进度更新移动到后台工作程序（您还可以在其中设置实际上有意义的值，例如，指示您已下载了多少“可用版本”）。 / p>

希望这是有道理的。

编辑：

假设我们将所有代码直接放在视图中，假设我们有一个名为＆＃39; progressBar＆＃39;的进度条。以及一个名为＆＃39; btnStart＆＃39;的按钮（背景工作者的踢法）。

这里是代码隐藏：

private BackgroundWorker worker;

 public MainWindow()
 {
    InitializeComponent();
    this.worker = new BackgroundWorker();

    this.worker.DoWork += new DoWorkEventHandler(myWorker_DoWork);
    this.worker.RunWorkerCompleted += new 
    RunWorkerCompletedEventHandler(myWorker_RunWorkerCompleted);
    this.worker.ProgressChanged += new 
    ProgressChangedEventHandler(myWorker_ProgressChanged);
    this.worker.WorkerReportsProgress = true;
    this.worker.WorkerSupportsCancellation = true;
}

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

private void myWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
     // Whatever you need to do when finished here (alert, update a label, etc.)
}

private void myWorker_DoWork(object sender, DoWorkEventArgs e)
{
    // Just loop and report new progress. Sleep a little in between each
    // progress update so that it isn't over before we have a chance to see it.
    for(int i=0;i<100;i++)
    {
        Thread.Sleep(200);
        this.worker.ReportProgress(i);
    }
}

private void btnStart_Click(object sender, RoutedEventArgs e)
{
    this.worker.RunWorkerAsync();
}

后台工作人员触发事件通知进度已发生变化。主线程具有该事件的句柄，并更新进度条。由于它是后台工作人员，因此您不需要使用Dispatcher.Invoke - 这已经得到了解决。

希望这个例子能为你澄清事情。

UI无响应+进度条在使用backgroundworker时无法正常工作c＃

2 个答案: