用http協(xié)議來下載網(wǎng)絡(luò)上的文件，通常我們需要獲取文件文件的下載進(jìn)度和下載的速度來給用戶等待過程的一個交代，那么在Windows Phone 7下可以使用WebClient類來實現(xiàn)這一功能，HttpWebRequest類也可以用于下載網(wǎng)絡(luò)上的文件，不過HttpWebRequest類不能夠直接地獲取你http請求的完成情況。

使用WebClient.DownloadProgressChanged事件來異步獲取http協(xié)議下載文件的進(jìn)度情況，使用WebClient.DownloadStringCompleted事件來判斷文件的下載是否完成。

<phone:PhoneApplicationPage   
    x:Class="DownLoadTest.MainPage" 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone" 
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone" 
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
    mc:Ignorable="d" d:DesignWidth="480" d:DesignHeight="768" 
    FontFamily="{StaticResource PhoneFontFamilyNormal}" 
    FontSize="{StaticResource PhoneFontSizeNormal}" 
    Foreground="{StaticResource PhoneForegroundBrush}" 
    SupportedOrientations="Portrait" Orientation="Portrait" 
    shell:SystemTray.IsVisible="True"> 
 
    <Grid x:Name="LayoutRoot" Background="Transparent"> 
        <Grid.RowDefinitions> 
            <RowDefinition Height="Auto"/> 
            <RowDefinition Height="*"/> 
        </Grid.RowDefinitions> 
          
        <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28"> 
            <TextBlock x:Name="ApplicationTitle" Text="MY APPLICATION" Style="{StaticResource PhoneTextNormalStyle}"/> 
            <TextBlock x:Name="PageTitle" Text="下載進(jìn)度顯示" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/> 
        </StackPanel> 
 
        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0"> 
            <Grid.RowDefinitions> 
                <RowDefinition Height="114*"/> 
                <RowDefinition Height="493*"/> 
            </Grid.RowDefinitions> 
            <ProgressBar Foreground="Green" Height="30" HorizontalAlignment="Left" Margin="9,79,0,0" Name="progressBar1" VerticalAlignment="Top" Width="377" Value="0" Maximum="100" FontSize="72" BorderThickness="0"/> 
            <TextBlock Height="53" Margin="12,20,-16,0" Name="textBox1" Text="正在下載文件 . . ." VerticalAlignment="Top" Width="460"/> 
            <TextBlock Margin="6,24,287,427" Name="result" Text="下載的速度:  " Grid.Row="1"/> 
            <TextBlock  Foreground="White" Height="59" HorizontalAlignment="Left" Margin="203,13,0,0" Name="textBox2" Text=""  VerticalAlignment="Top" Width="123"/> 
            <Button Content="測試下載" Height="72" HorizontalAlignment="Left" Margin="96,244,0,0" Name="button1" VerticalAlignment="Top" Width="199" Click="button1_Click" Grid.Row="1"/> 
            <TextBlock Height="59"  Margin="2,101,254,0" Name="finalresult" Text="平均的下載速度:  " VerticalAlignment="Top" Grid.Row="1"/> 
            <TextBlock Height="57" HorizontalAlignment="Left" Margin="174,89,0,0" Name="textBlock1" Text="" VerticalAlignment="Top" Width="156" Grid.Row="1"/> 
            <TextBlock Height="47" HorizontalAlignment="Left" Margin="12,166,0,0" Name="textBlock2" Text="文件的大?。?quot; VerticalAlignment="Top" Width="127" Grid.Row="1"/> 
            <TextBlock Height="47" HorizontalAlignment="Right" Margin="0,166,190,0" Name="textBlock3" Text="" VerticalAlignment="Top" Grid.Row="1" Width="121"/> 
            <TextBlock Height="47" HorizontalAlignment="Right" Margin="0,19,190,0" Name="textBlock4" Text="" VerticalAlignment="Top" Grid.Row="1" Width="134"/> 
        </Grid> 
    </Grid> 
</phone:PhoneApplicationPage> 

using System;  
using System.Net;  
using System.Windows;  
using Microsoft.Phone.Controls;  
using System.Diagnostics;  
 
namespace DownLoadTest  
{  
    public partial class MainPage : PhoneApplicationPage  
    {  
        private long siz;  
        private long speed;  
        private Stopwatch sw;  
        private Stopwatch sw1;  
 
        public MainPage()  
        {  
            InitializeComponent();  
        }  
 
        private void button1_Click(object sender, RoutedEventArgs e)  
        {  
            testspeed();  
        }  
 
        public void testspeed()  
        {  
            WebClient client = new WebClient();  
            progressBar1.Value = 0.0;  
            textBox2.Text = "0 %";  
            client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(this.webClient_DownloadStringCompleted);  
            client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(this.webClient_DownloadProgressChanged);  
            sw = Stopwatch.StartNew();//用來記錄總的下載時間  
            sw1 = Stopwatch.StartNew();//用來記錄下載過程中的時間片，用于計算臨時速度  
            client.DownloadStringAsync(new Uri("http://dl_dir.qq.com/qqfile/qq/QQ2011/QQ2011.exe"));  
        }  
        //下載過程事件  
        public void webClient_DownloadProgressChanged(object s, DownloadProgressChangedEventArgs e)  
        {  
            textBox2.Text = e.ProgressPercentage.ToString() + " %";  
            sw1.Stop();  
            long num = e.BytesReceived / 1024;  
            if (sw1.Elapsed.Seconds != 0)  
            {  
                speed = num / ((long)sw1.Elapsed.Seconds);  
            }  
            textBlock4.Text = this.speed + " KB/sec";  
            progressBar1.Value = e.ProgressPercentage;  
            siz = e.TotalBytesToReceive;  
            textBlock3.Text = siz + "KB";  
            sw1.Start();  
        }  
        //下載完成事件  
        public void webClient_DownloadStringCompleted(object s, DownloadStringCompletedEventArgs e)  
        {  
            sw.Stop();  
            sizsiz = siz/1024;  
            long num = siz / ((long)sw.Elapsed.Seconds);  
            sw.Reset();  
            textBox1.Text = "下載完成！";  
            textBlock1.Text = num + " KBytes/sec";  
        }  
    }  
} 

原文鏈接：http://www.cnblogs.com/linzheng/archive/2011/11/03/2234971.html