为什么使用WebClient不能下载~是模拟器出有关问题吗

为什么使用WebClient不能下载~~是模拟器出问题吗？
本帖最后由 q8547957 于 2012-10-21 11:49:47 编辑 貌似不能下载那张图片~~总是不显示~~~要点击那个显示图片流的键~
下载的进度条也不会走~~

MainPage.xaml.cs文件：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;
using System.Windows.Media.Imaging;
using System.Text;
using System.IO;

namespace ImageToByte
{
    public partial class MainPage : PhoneApplicationPage
    {
        // 构造函数
        public MainPage()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                Uri img = new Uri("http://img6.ph.126.net/xMMHX5vxqilnYgG7qxSkYQ==/6597751463865557506.jpg", UriKind.RelativeOrAbsolute);
                //使用WebClent下载图片
                WebClient wc = new WebClient();
                //注册OpenRead事件
                wc.OpenReadCompleted += new OpenReadCompletedEventHandler(wc_OpenReadCompleted);
                //下载进度事件
                wc.DownloadProgressChanged +=new DownloadProgressChangedEventHandler(wc_DownloadProgressChanged);

                //异步调用
                wc.OpenWriteAsync(img);
            }
            catch (Exception es)
            {
                MessageBox.Show(es.Message);
            }

        }

        void wc_OpenReadCompleted(object sender,OpenReadCompletedEventArgs e) 
        {
            Stream stream = e.Result;
            BitmapImage bitmap = new BitmapImage(); 
 
            bitmap.SetSource(stream);
            showImage.Source = bitmap;
            
        }

        void wc_DownloadProgressChanged (object sender,DownloadProgressChangedEventArgs e)
        {
            this.Dispatcher.BeginInvoke(() =>
            {
                progressBar1.Value = e.ProgressPercentage;

            });
        }
    }
}

<phone:PhoneApplicationPage 
    x:Class="ImageToByte.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">

    <!--LayoutRoot 是包含所有页面内容的根网格-->
    <Grid x:Name="LayoutRoot" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!--TitlePanel 包含应用程序的名称和页标题-->
        <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
            <TextBlock x:Name="ApplicationTitle" Text="我的应用程序" Style="{StaticResource PhoneTextNormalStyle}"/>
            <TextBlock x:Name="PageTitle" Text="页面名称" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
        </StackPanel>

        <!--ContentPanel - 在此处放置其他内容-->
        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <Button Content="显示图片流" Height="72" HorizontalAlignment="Left" Margin="27,272,0,0" Name="button1" VerticalAlignment="Top" Width="183" Click="button1_Click" /> 
 
            <Button Content="显示图片" Height="72" HorizontalAlignment="Right" Margin="0,272,38,0" Name="button2" VerticalAlignment="Top" Width="160" />
            <Image Height="260" HorizontalAlignment="Left" Margin="6,6,0,0" Name="showImage" Stretch="Fill" VerticalAlignment="Top" Width="444" />
            <ScrollViewer Height="201" HorizontalAlignment="Left" Margin="9,400,0,0" Name="scrollViewer1" VerticalAlignment="Top" Width="441">
                <TextBlock Height="30" Name="showCode" Text="TextBlock" />
            </ScrollViewer>
            <ProgressBar Height="26" HorizontalAlignment="Left" Margin="6,350,0,0" Name="progressBar1" VerticalAlignment="Top" Width="460" />
        </Grid>
    </Grid>
 
    <!--演示 ApplicationBar 用法的示例代码-->
    <!--<phone:PhoneApplicationPage.ApplicationBar>
        <shell:ApplicationBar IsVisible="True" IsMenuEnabled="True">
            <shell:ApplicationBarIconButton IconUri="/Images/appbar_button1.png" Text="按钮 1"/>
            <shell:ApplicationBarIconButton IconUri="/Images/appbar_button2.png" Text="按钮 2"/>
            <shell:ApplicationBar.MenuItems>
                <shell:ApplicationBarMenuItem Text="菜单项 1"/>
                <shell:ApplicationBarMenuItem Text="菜单项 2"/>
            </shell:ApplicationBar.MenuItems>
        </shell:ApplicationBar>
    </phone:PhoneApplicationPage.ApplicationBar>-->

</phone:PhoneApplicationPage>