如何使用ProgressBar更新正确实现BackgroundWorker？

小编典典

如何使用ProgressBar更新正确实现BackgroundWorker？

-Updated–14 / 10
也问了这个问题

为了对发生的事情有一个清晰的了解，并考虑到评论，本文的内容也来自这里

我现在真正想做的是调用一个带有进度条的新表单，并使其运行并进行动画处理，同时我的后台线程将我的长进程运行到数据库中，然后调用关闭表单事件

后台工作者在这里设置

 public partial class MainWindow : Window
{
    //Declare background workers
    BackgroundWorker bw = new BackgroundWorker();
    BackgroundWorker bwLoadCSV = new BackgroundWorker();
    BackgroundWorker bwProgressBar = new BackgroundWorker();

然后代表们在这里添加

  public MainWindow()
    {
        bwLoadCSV.WorkerReportsProgress = true;
        bwLoadCSV.WorkerSupportsCancellation = true;
        bwLoadCSV.DoWork += new DoWorkEventHandler(bwLoadCSV_DoWork);
        bwLoadCSV.ProgressChanged += new ProgressChangedEventHandler(bwLoadCSV_ProgressChanged);
        bwLoadCSV.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bwLoadCSV_RunWorkerCompleted);

调用是从主窗口类在这里进行的

  private void CSV_Load_Click(object sender, RoutedEventArgs e)
    ///Function to read csv into datagrid
    ///
    {
        //Turn Cursor to wait
        System.Windows.Forms.Cursor.Current = System.Windows.Forms.Cursors.WaitCursor;

        //Test connection to sql server
        if (CHHoursDataProvider.IsDatabaseOnline() == false)
        {
            System.Windows.Forms.MessageBox.Show("Can not establish contact with sql server" + "\n" + "Contact IT", "Connection Error");
            //Set UI picture
            return;
        }
        //Set a control to update the user here
        tbLoadDgStat.Visibility = Visibility.Visible;

        tbLoadDgStat.Text = "Getting data templete from Database...";
        string FilePath = txFilePath.Text;
        if (bwLoadCSV.IsBusy != true)
        {
            //load the context object with parameters for Background worker
            bwCSVLoadContext Context = new bwCSVLoadContext();
            Context.Site = cBChSite.Text;
            Context.FilePath = txFilePath.Text;
            Context.FileName = fileTest;
            Context.Wageyear = cbWageYear.Text;
            Context.Startdate = ((DateTime)dpStartDate.SelectedDate);
            Context.Enddate = ((DateTime)dpEndDate.SelectedDate);

            bwLoadCSV.RunWorkerAsync(Context);

        }

后台工作者做的工作是

private void bwLoadCSV_DoWork(object sender, DoWorkEventArgs e)
    {
        BackgroundWorker worker = sender as BackgroundWorker;

        bwCSVLoadContext Context = e.Argument as bwCSVLoadContext;


        worker.ReportProgress((10));
        if ((worker.CancellationPending == true))
        {
            e.Cancel = true;

        }
        else
        {
            // Perform a time consuming operation and report progress load csv into datagrid.

为了报告后台工作，我这样做。在这里，我试图加载一个新的名为ProgressDialog的表单，该表单上有一个进度条，我尝试将其设置为Indeterminable，这样它就可以在我的ProgressDialoge表单中“摆动”，以向用户显示正在进行的操作。我已经使用了后台工作中的报告程序部分，因为我相信它可以访问主窗口线程，并且我希望从主窗口线程中调用invoke方法，但是我不确定

这是记者

 private void bwLoadCSV_ProgressChanged(object sender, ProgressChangedEventArgs e)

    {


        this.Dispatcher.Invoke((MethodInvoker)delegate { tbLoadDgStat.Visibility = Visibility.Visible; });
        //tbLoadDgStat.Visibility = Visibility.Visible;


        //this.progressBar1.Value = e.ProgressPercentage;//This works but pauses on long steps
        if (e.ProgressPercentage == 10)
        {
            //Try to open a new form with a class ProgressDialog and set the progressbar
            // on the frm to IsIndeterminate=true
            //THIS IS NOT WORKING
            this.Dispatcher.BeginInvoke (new Action(() =>
              {  ProgressDialog progressDialog = new ProgressDialog();
                progressDialog.SetIndeterminate(true);
            }));

             //this updates the main form OK
             this.Dispatcher.Invoke((MethodInvoker)delegate { tbLoadDgStat.Text = "Getting data templete from Database..."; });

        }
        else if (e.ProgressPercentage == 20)
        {

            this.Dispatcher.Invoke((MethodInvoker)delegate { tbLoadDgStat.Text = "Data template retrieved..."; });

        }
        else
        {

            if (e.ProgressPercentage % 10 == 0)
            {
                this.Dispatcher.Invoke((MethodInvoker)delegate { tbLoadDgStat.Text = "Adding Data..." + e.ProgressPercentage.ToString() + "%"; });
            }
        }

最后是ProgressDialog表单的xaml及其类

<Window x:Class="Test_Read_CSV.ProgressDialog"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Progress Dialog" Height="115" Width="306" Name="ProgressPopup">
<Grid>
    <ProgressBar Height="31" HorizontalAlignment="Left" Margin="12,33,0,0" Name="progressBar1" VerticalAlignment="Top" Width="250" />
    <TextBox Height="23" HorizontalAlignment="Left" Margin="7,4,0,0" Name="tbEvent" VerticalAlignment="Top" Width="254" IsReadOnly="True" IsEnabled="False" />
</Grid>

类

/// <summary>
/// Interaction logic for ProgressDialog.xaml
/// </summary>
public partial class ProgressDialog : Window
{
    public ProgressDialog()
    {
        WindowStartupLocation = WindowStartupLocation.CenterScreen;
        InitializeComponent();
    }

    public ProgressDialog(String Purpose)
    {
        InitializeComponent();
        tbEvent.Text = Purpose;
        WindowStartupLocation = WindowStartupLocation.CenterScreen;

    }
    public void UpdateProgress(int progress)
    {
        progressBar1.Dispatcher.BeginInvoke(
            new Action(() =>
            {
                progressBar1.Value = progress;
            }
        ));
    }

    public void SetIndeterminate(bool isIndeterminate)
    {
        progressBar1.Dispatcher.BeginInvoke(
            new Action(() =>
            {
                if (isIndeterminate)
                {
                    progressBar1.IsIndeterminate = true;
                }
                else
                {
                    progressBar1.IsIndeterminate = false;
                }
            }
        ));
    }
}

}

我已经阅读并完成了一些有关后台工作者的教程，甚至还涉及了一些线程，但似乎无法获得我想要的结果

我的想法是，我有两个漫长的过程，我要么从远程bd获取数据表克隆，要么从wpf应用程序（.net
4）更新数据库。在进程运行时，我希望有一个进度条控件并对其进行更新，原因很明显，这是为了明确一些工作正在进行。因此，我在后台工作程序中执行了常规的报告进度例程，并且可以正常工作…但是，在我的dowork线程中，我有以下命令

CHHoursDataProvider CH = new CHHoursDataProvider();
oTable = CH.CloneCHHours();

这是与db进行通信的地方，并且该命令在vpn远程连接上花费了60-90秒，因此即使我这样做

CHHoursDataProvider CH = new CHHoursDataProvider();
worker.ReportProgress((10));
oTable = CH.CloneCHHours();
worker.ReportProgress((20));

主窗口看起来仍然冻结，好像已经崩溃了！

因此，我要做的就是在调用后台工作的开始时将进度条设置为运行，并使其保持运行状态直到任务结束。这是完成我的第一个项目所需要做的，三天后，我仍然无法解决这个问题！

所以我尝试了以下

在bw中，进度已更改，并且在主窗口类中

 this.progressBar2.IsIndeterminate = true;

但是，动画直到Dowork线程完成才开始。

然后，我创建了另一个后台工作程序来更新progressbar2，该程序链接到主窗口上的按钮是可以的，但是当我尝试从另一个后台工作程序或主窗口类中使用它时，直到工作完成后，线程已在第一个后台工作者上完成

然后，我尝试遵循一个invoke方法，但真的迷失了！

所以任何人都可以帮忙，我可以猜测这与线程和在错误的线程上工作等有关，但是我对此一无所知。

我可以根据需要发布更多代码

伊恩

阅读 428

2020-05-19

共1个答案

小编典典

由于您没有显示完整的BackgroundWorker代码，所以我无法确定您是否正确实现了它。这样，我所能做的就是向您展示一个更新ProgressBar控件的简单工作示例：

UserControl XAML：

<UserControl x:Class="WpfApplication1.Views.TestView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
    mc:Ignorable="d" 
    d:DesignHeight="300" d:DesignWidth="300" Loaded="UserControl_Loaded">
    <ProgressBar x:Name="progressBar" Height="25" Margin="20" Minimum="0" 
        Maximum="50" />
</UserControl>

MainWindow XAML：

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:Views="clr-namespace:WpfApplication1.Views"
    Title="MainWindow" Height="350" Width="525">
    <Views:TestView />
</Window>

UserControl 后面的代码：

using System.ComponentModel;
using System.Threading;
using System.Windows;
using System.Windows.Controls;

namespace WpfApplication1.Views
{
    public partial class TestView : UserControl
    {
        private BackgroundWorker backgroundWorker = new BackgroundWorker();

        public TestView()
        {
            InitializeComponent();
            backgroundWorker.WorkerReportsProgress = true;
            backgroundWorker.ProgressChanged += ProgressChanged;
            backgroundWorker.DoWork += DoWork;
            // not required for this question, but is a helpful event to handle
            backgroundWorker.RunWorkerCompleted += BackgroundWorker_RunWorkerCompleted;
        }

        private void UserControl_Loaded(object sender, RoutedEventArgs e)
        {
            backgroundWorker.RunWorkerAsync();
        }

        private void DoWork(object sender, DoWorkEventArgs e)
        {
            for (int i = 0; i <= 100; i++)
            {
                // Simulate long running work
                Thread.Sleep(100);
                backgroundWorker.ReportProgress(i);
            }
        }

        private void ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            // This is called on the UI thread when ReportProgress method is called
            progressBar.Value = e.ProgressPercentage;
        }

        private void BackgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            // This is called on the UI thread when the DoWork method completes
            // so it's a good place to hide busy indicators, or put clean up code
        }
    }
}

2020-05-19