Question

我正在尝试显示远程托管的XML文件中的元素并显示在列表框中。

当我按下按钮时，我收到正式异常未得到处理。我附上了错误的屏幕截图！[在此处输入图片说明] [1]

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 Microsoft.Phone.Tasks;
using System.Xml;
using System.Xml.Linq;

namespace tvGuide
{
    public partial class MainPage : PhoneApplicationPage
    {
        // Constructor
        public MainPage()
        {
            InitializeComponent();

         }



        private void button1_Click(object sender, RoutedEventArgs e)
        {
            WebClient c = new WebClient();
            c.DownloadStringCompleted += new DownloadStringCompletedEventHandler(c_DownloadStringCompleted);
            c.DownloadStringAsync(new Uri("http://www.designized.com/tv/freeview.xml?"));
        }

        void c_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
        {
            if (e.Error != null)
                return;

            XElement r = XElement.Parse(e.Result);


            listBox1.ItemsSource = from tv in r.Descendants("programme")
                                   select new TVNZ
                                   {
                                       DisplayName = Convert.ToInt32(tv.Element("title").Value),
                                       ChannelURL = Convert.ToInt32(tv.Element("category").Value),
                                      ImageSource = Convert.ToInt32(tv.Element("url").Value),



                                   };
        }
        }

        public class TVNZ
        {
            public int DisplayName { get; set; }
            public int ChannelURL { get; set; }
            public int ImageSource { get; set; }



        }





    }

mainpage.xaml next ...

<phone:PhoneApplicationPage 
    x:Class="tvGuide.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:task="clr-namespace:Microsoft.Phone.Tasks;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 is the root grid where all page content is placed-->
    <Grid x:Name="LayoutRoot" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!--TitlePanel contains the name of the application and page title-->
        <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="page name" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
        </StackPanel>

        <!--ContentPanel - place additional content here-->
        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <ListBox Height="595" HorizontalAlignment="Left" Margin="6,6,0,0" Name="listBox1" VerticalAlignment="Top" Width="444">
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal" Height="132">
                            <Image Source="{Binding ImageSource}" Height="73" Width="73" VerticalAlignment="Top" Margin="0,10,8,0"/>
                            <StackPanel Width="370">
                                <TextBlock Text="{Binding DisplayName}" Foreground="#FFC8AB14" FontSize="28" />
                                <TextBlock Text="{Binding ChannelURL}" TextWrapping="Wrap" FontSize="24" />
                            </StackPanel>
                        </StackPanel>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>
        </Grid>
    </Grid>

    <!--Sample code showing usage of ApplicationBar-->
    <!--<phone:PhoneApplicationPage.ApplicationBar>
        <shell:ApplicationBar IsVisible="True" IsMenuEnabled="True">
            <shell:ApplicationBarIconButton IconUri="/Images/appbar_button1.png" Text="Button 1"/>
            <shell:ApplicationBarIconButton IconUri="/Images/appbar_button2.png" Text="Button 2"/>
            <shell:ApplicationBar.MenuItems>
                <shell:ApplicationBarMenuItem Text="MenuItem 1"/>
                <shell:ApplicationBarMenuItem Text="MenuItem 2"/>
            </shell:ApplicationBar.MenuItems>
        </shell:ApplicationBar>
    </phone:PhoneApplicationPage.ApplicationBar>-->

</phone:PhoneApplicationPage>

现在问题中的XML文件：

<tv date="20110708031152" generator-info-name="epgsnoop/0.84" generator-info-url="http://launchpad.net/epgsnoop">
- <channel id="maori-tv.freeviewnz.tv">
  <display-name>Maori TV</display-name> 
  <icon src="http://nzepg.org/logos/maori.jpg" /> 
  <url>http://www.freeviewnz.tv/</url> 
  </channel>
- <channel id="georgefm.freeviewnz.tv">
  <display-name>GeorgeFM</display-name> 
  </channel>
- <channel id="basefm.freeviewnz.tv">
  <display-name>BaseFM</display-name> 
  </channel>
- <channel id="rnz-concert.freeviewnz.tv">
  <display-name>RNZ Concert</display-name> 
  </channel>
- <channel id="stratos.freeviewnz.tv">
  <display-name>Stratos</display-name> 
  <icon src="http://nzepg.org/logos/stratos.jpg" /> 
  <url>http://www.stratostv.co.nz/</url> 
  </channel>
- <channel id="tv3.freeviewnz.tv">
  <display-name>TV 3</display-name> 
  <icon src="http://nzepg.org/logos/tv3.jpg" /> 
  <url>http://www.tv3.co.nz/</url> 
  </channel>
- <channel id="four.freeviewnz.tv">
  <display-name>Four</display-name> 
  <icon src="http://nzepg.org/logos/four.jpg" /> 
  </channel>
- <channel id="tvnz7.freeviewnz.tv">
  <display-name>TVNZ 7</display-name> 
  <icon src="http://nzepg.org/logos/tvnz7.jpg" /> 
  <url>http://www.freeviewnz.tv/</url> 
  </channel>
- <channel id="parliament.freeviewnz.tv">
  <display-name>Parliament</display-name> 
  <icon src="http://nzepg.org/logos/parliament.jpg" /> 
  <url>http://www.freeviewnz.tv/</url> 
  </channel>

非常感谢任何帮助。

Answer 1

我试图运行它，但代码中存在一些问题

所有那些字段必须是字符串而不是int！
所有都是可选的，需要检查null
属性名称读取的内容与xml中的内容不同！

这有效：

var r = XDocument.Parse(e.Result);
listBox1.ItemsSource = from tv in r.Root.Descendants("channel")
                        let nameEl = tv.Element("display-name")
                        let urlEl = tv.Element("url")
                        let iconEl = tv.Element("icon")
                        select new TVNZ
                        {
                            DisplayName = nameEl == null ? null : nameEl.Value,
                            ChannelURL = urlEl == null ? null : urlEl.Value,
                            ImageSource = iconEl == null ? null : iconEl.Attribute("src").Value,
                        };

也将课程改为：

public class TVNZ
{
    public string DisplayName { get; set; }
    public string ChannelURL { get; set; }
    public string ImageSource { get; set; }
}

结论：首先在开始编码之前定义您的问题域。

只有一个方面，使用WebClient完全在UI线程上运行，并且您的应用程序没有响应，直到响应回来。所以建议使用HttpWebRequest，它可以在一个单独的线程上运行。

Here in my blog post我已经为异步网络下载目的准备了一个帮助程序类。随意使用。

WP7 / Silverlight - 无法使用Linq和WebClient显示XML元素

1 个答案: