Windows Phone开发基础（11）实现一个RSS阅读器

实现一个RSS阅读器，通过你输入的RSS地址来获取RSS的信息列表和查看RSS文章中的详细内容。RSS阅读器是使用了WebClient类来获取网络上的RSS的信息，然后再转化为自己定义好的RSS实体类对象的列表，最后绑定到页面上。

（1） RSS实体类和RSS服务类

RssItem.cs

using System.Net;
using System.Text.RegularExpressions;

namespace WindowsPhone.Helpers
{
    ///<summary>
    /// RSS对象类
    ///</summary>
publicclass RssItem
    {
        ///<summary>
        /// 初始化一个RSS目录
        ///</summary>
        ///<param name="title">标题</param>
        ///<param name="summary">内容</param>
        ///<param name="publishedDate">发表事件</param>
        ///<param name="url">文章地址</param>
public RssItem(string title, string summary, string publishedDate, string url)
        {
            Title = title;
            Summary = summary;
            PublishedDate = publishedDate;
            Url = url;

            //解析html
            PlainSummary = HttpUtility.HtmlDecode(Regex.Replace(summary, "<[^>]+?>", ""));
        }

        //标题
publicstring Title { get; set; }

        //内容
publicstring Summary { get; set; }

        //发表时间
publicstring PublishedDate { get; set; }

        //文章地址
publicstring Url { get; set; }

        //解析的文本内容
publicstring PlainSummary { get; set; }
    }
}

RssService.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.ServiceModel.Syndication;
using System.Xml;

namespace WindowsPhone.Helpers
{
    ///<summary>
    /// 获取网络RSS服务类
    ///</summary>
publicstaticclass RssService
    {
        
        ///<summary>
        /// 获取RSS目录列表
        ///</summary>
        ///<param name="rssFeed">RSS的网络地址</param>
        ///<param name="onGetRssItemsCompleted">获取完成事件</param>
publicstaticvoid GetRssItems(string rssFeed, Action<IEnumerable<RssItem>> onGetRssItemsCompleted =null, Action<Exception> onError =null, Action onFinally =null)
        {
            WebClient webClient =new WebClient();

            //注册webClient读取完成事件
            webClient.OpenReadCompleted +=delegate(object sender, OpenReadCompletedEventArgs e)
            {
                try
                {

                    if (e.Error !=null)
                    {
                        if (onError !=null)
                        {
                            onError(e.Error);
                        }
                        return;
                    }

                    //将网络获取的信息转化成RSS实体类
                    List<RssItem> rssItems =new List<RssItem>();
                    Stream stream = e.Result;
                    XmlReader response = XmlReader.Create(stream);
                    SyndicationFeed feeds = SyndicationFeed.Load(response);
                    foreach (SyndicationItem f in feeds.Items)
                    {
                        RssItem rssItem =new RssItem(f.Title.Text, f.Summary.Text, f.PublishDate.ToString(), f.Links[0].Uri.AbsoluteUri);
                        rssItems.Add(rssItem);
                    }

                    //通知完成返回事件执行
if (onGetRssItemsCompleted !=null)
                    {
                        onGetRssItemsCompleted(rssItems);
                    }
                }
                finally
                {
                    if (onFinally !=null)
                    {
                        onFinally();
                    }
                }
            };

            webClient.OpenReadAsync(new Uri(rssFeed));
        }
    }
}

（2） RSS页面展示

MainPage.xaml

<phone:PhoneApplicationPage 
    x:Class="ReadRssItemsSample.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="RSS阅读器" Style="{StaticResource PhoneTextNormalStyle}"/>
        </StackPanel>

        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
                <RowDefinition  Height="*"/>
            </Grid.RowDefinitions>
            <TextBlock FontSize="30" Grid.Row="1" Height="49" HorizontalAlignment="Left" Margin="0,6,0,0" Name="textBlock1" Text="RSS地址" VerticalAlignment="Top" Width="116"/>
            <TextBox Grid.Row="1" Height="72" HorizontalAlignment="Left" Margin="107,0,0,0" Name="rssURL" Text="http://www.cnblogs.com/rss" VerticalAlignment="Top" Width="349"/>
            <Button Content="加载 RSS" Click="Button_Click" Margin="-6,72,6,552" Grid.Row="1"/>
            <ListBox x:Name="listbox" Grid.Row="1" SelectionChanged="OnSelectionChanged" Margin="0,150,6,-11">
                <ListBox.ItemTemplate  >
                    <DataTemplate>
                        <Grid>
                            <Grid.RowDefinitions>
                                <RowDefinition Height="Auto"/>
                                <RowDefinition Height="Auto"/>
                                <RowDefinition Height="60"/>
                            </Grid.RowDefinitions>
                            <TextBlock Grid.Row="0" Text="{Binding Title}" Foreground="Blue"/>
                            <TextBlock Grid.Row="1" Text="{Binding PublishedDate}" Foreground="Green"/>
                            <TextBlock Grid.Row="2" TextWrapping="Wrap" Text="{Binding PlainSummary}"/>
                        </Grid>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>
        </Grid>
    </Grid>
 
</phone:PhoneApplicationPage>

MainPage.xaml.cs

using System.Windows;
using System.Windows.Controls;
using Microsoft.Phone.Controls;
using WindowsPhone.Helpers;

namespace ReadRssItemsSample
{
    publicpartialclass MainPage : PhoneApplicationPage
    {
        privatestring WindowsPhoneBlogPosts ="";

        public MainPage()
        {
            InitializeComponent();
        }

        privatevoid Button_Click(object sender, RoutedEventArgs e)
        {
            if (rssURL.Text !="")
            {
                WindowsPhoneBlogPosts = rssURL.Text;
            }
            else
            {
                MessageBox.Show("请输入RSS地址！");
                return;
            }
            //加载RSS列表
            RssService.GetRssItems(
                WindowsPhoneBlogPosts,
                (items) => { listbox.ItemsSource = items; },
                (exception) => { MessageBox.Show(exception.Message); },
                null
                );
        }

        //查看文章的详细内容
privatevoid OnSelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            if (listbox.SelectedItem ==null)
                return;

            var template = (RssItem)listbox.SelectedItem;

            MessageBox.Show(template.PlainSummary);

            listbox.SelectedItem =null;
        }

    }
}