WPF 循环读取文件中实现进度条显示

转自:http://blog.csdn.net/webkis/article/details/5977399

<Window x:Class="MyWPF.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="DownLoad Demo" Height="350" Width="525" Loaded="Window_Loaded">
    <Window.Background>
        <LinearGradientBrush>
            <GradientStop Color="Red" Offset="0"></GradientStop>
            <GradientStop Color="Yellow" Offset="0.5"></GradientStop>
        </LinearGradientBrush>
    </Window.Background>
    <Grid>
        <Label x:Name="txtWords"></Label>
        <StackPanel Orientation="Horizontal" HorizontalAlignment="Right" VerticalAlignment="Bottom">
            <Button Content="start download" Width="120" Height="23" Margin="8" Click="Button_Click">
                <Button.Effect>
                    <DropShadowEffect Color="Blue" BlurRadius="1"></DropShadowEffect>
                </Button.Effect>
            </Button>
            <Button Content="cancel" Width="70" Height="23" Margin="8" Click="Button_Click_1">
                <Button.Effect>
                    <DropShadowEffect Color="Blue" BlurRadius="1"></DropShadowEffect>
                </Button.Effect>
            </Button>
        </StackPanel>
        <Rectangle Width="220" Stroke="Red" StrokeThickness="2" Height="60" RadiusX="5" RadiusY="5">
        </Rectangle>
        <ProgressBar x:Name="progressBar" Width="180" Height="23" />
    </Grid>
</Window>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.ComponentModel;

namespace MyWPF
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        BackgroundWorker worker;
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            txtWords.Content = "download demo.";
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            worker = new BackgroundWorker();
            worker.WorkerReportsProgress = true;
            worker.WorkerSupportsCancellation = true;
            worker.DoWork += new DoWorkEventHandler(worker_DoWork);
            worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);
            worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);

            progressBar.Value = 0;
            txtWords.Content = "downloading...";
            worker.RunWorkerAsync();
        }

        void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            Action<string> act = delegate(string str)
            {
                txtWords.Content = str;
            };
            if (e.Cancelled)
                this.Dispatcher.BeginInvoke(act, "download cancelled.");
            else
                this.Dispatcher.BeginInvoke(act, e.Result.ToString());
        }

        private static string Download(string url, string name, object sender,DoWorkEventArgs e)
        {
            BackgroundWorker w = sender as BackgroundWorker;
            for (int i = 0; i < 100; i++)
            {
                System.Threading.Thread.Sleep(50);
                w.ReportProgress(i + 1);
                if (w.CancellationPending)
                {
                    e.Cancel = true;
                    return "";
                }
            }
            return "download completed, download " + DateTime.Now.Millisecond + "byte";
        }

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

        void worker_DoWork(object sender, DoWorkEventArgs e)
        {
            e.Result = Download("", "", sender, e);
        }

        private void Button_Click_1(object sender, RoutedEventArgs e)
        {
            worker.CancelAsync();
            txtWords.Content = "download demo.";
            progressBar.Value = 0;
        }
    }
}

 在后来http://developer.51cto.com/art/200912/173330.htm的文章中看到如下方法很好的解决了我自己的实际问题.

double value=0;  
for (.....)  
{  
progressBar.Dispatcher.Invoke(new Action<System.Windows.DependencyProperty, 
object>(progressBar.SetValue), 
System.Windows.Threading.DispatcherPriority.Background, 
ProgressBar.ValueProperty, value);  
value++;  
}