F6 Team

最近看到很多Silverlight的文章,整理出這一篇文章

敎大家如何用Silverlight做一個簡易的RSS閱讀器

首先利用HttpWebRequest來取得RSS的資料,相關的用法可以參考下面網址:

Using WebClient and HttpWebRequest
http://blogs.msdn.com/silverlight_sdk/archive/2008/04/01/using-webclient-and-httpwebrequest.aspx

 

再將下載回來的RSS XML資料轉換成SyndicationFeed這個類別,SyndicationFeed相關介紹請參考下面網址:

使用 RSS 或 Atom 摘要
http://msdn.microsoft.com/zh-tw/library/cc296253(VS.95).aspx

 

如果遇到跨網域存取的問題[安全性錯誤],請參考下面網址:

使用 Silverlight 的 HTTP 通訊和安全性
http://msdn.microsoft.com/zh-tw/library/cc838250(VS.95).aspx

 

如果遇到跨執行緒存取的問題[無效的跨執行緒存取],請參考下面網址:

In Silverlight, how to invoke an operation on the Main Dispatch Thread?
http://stackoverflow.com/questions/222688/in-silverlight-how-to-invoke-an-operation-on-the-main-dispatch-thread

說了這麼多,直接看程式碼吧..

RssReader.xaml

<UserControl xmlns:data="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Data" x:Class="SilverlightApplication1.RssReader" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:src="clr-namespace:SilverlightApplication1" Width="400" Height="300"> <UserControl.Resources> <src:LinkFormatter x:Key="linkFormatter"/> </UserControl.Resources> <Grid x:Name="LayoutRoot" Background="White"> <StackPanel> <StackPanel Height="25" Orientation="Horizontal"> <Button Width="50" Height="25" x:Name="btnRefresh" Content="更新" Click="btnRefresh_Click"></Button> </StackPanel> <StackPanel> <data:DataGrid AutoGenerateColumns="False" x:Name="dg"> <data:DataGrid.Columns> <data:DataGridTemplateColumn Header="標題" IsReadOnly="True"> <data:DataGridTemplateColumn.CellTemplate> <DataTemplate> <HyperlinkButton Content="{Binding Title.Text}" NavigateUri="{Binding Links,Converter={StaticResource linkFormatter}}" TargetName="_blank" ></HyperlinkButton> </DataTemplate> </data:DataGridTemplateColumn.CellTemplate> </data:DataGridTemplateColumn> </data:DataGrid.Columns> </data:DataGrid> </StackPanel> </StackPanel> </Grid> </UserControl>

RssReader.xaml.cs

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 System.Xml; using System.ServiceModel.Syndication; using System.Windows.Data; namespace SilverlightApplication1 { public partial class RssReader : UserControl { delegate void SetFeedCallback(SyndicationFeed feed); public RssReader() { InitializeComponent(); btnRefresh_Click(this, new RoutedEventArgs());//初始時,先載入RSS資訊 } //更新RSS資訊 private void btnRefresh_Click(object sender, RoutedEventArgs e) { Uri uri = new Uri("http://localhost:9161/rss.xml");//測試的RSS資料 HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create((uri)); request.BeginGetResponse(new AsyncCallback(ReadCallback), request); } private void ReadCallback(IAsyncResult asynchronousResult) { //解決[安全性錯誤][System.Security.SecurityException] //這邊可能會遇到[安全性錯誤]問題,因為如果跨網域存取,會有安全性的考量 //解決方法加入一個crossdomain.xml,來允許存取 HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState; HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asynchronousResult); XmlReader reader = XmlReader.Create(response.GetResponseStream()); SyndicationFeed feed = SyndicationFeed.Load(reader); //解決[無效的跨執行緒存取][System.UnauthorizedAccessException] //這行可能會有[無效的跨執行緒存取]的問題 //this.dg.ItemsSource = feed.Items; SetFeedCallback c = new SetFeedCallback(SetFeed); this.Dispatcher.BeginInvoke(c, new object[] { feed }); } private void SetFeed(SyndicationFeed feed) { this.dg.ItemsSource = feed.Items; } } //Links 屬性是一個集合，而其資料無法直接繫結至屬於 Uri 型別的 NavigateUri 屬性,要執行轉換的動作 public class LinkFormatter : IValueConverter { #region IValueConverter 成員 public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { return ((ICollection<SyndicationLink>)value).FirstOrDefault().Uri; } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { throw new NotImplementedException(); } #endregion } }

rss.xml

<rss version="2.0"> <channel> <title>點部落-修練大會專區</title> <link>http://www.dotblogs.com.tw/MainFeed.aspx?GroupID=111</link> <description>IT技術知識社群</description> <item> <title>[Robotics Studio x1] 初體驗</title> <link>http://www.dotblogs.com.tw/janyeh/archive/2008/12/04/6187.aspx</link> <pubDate>Wed, 03 Dec 2008 22:06:36 GMT</pubDate> </item> <item> <title>XNA簡介及遊戲開發流程</title> <link>http://www.dotblogs.com.tw/sonic10690/archive/2008/12/04/6182.aspx</link> <pubDate>Wed, 03 Dec 2008 17:20:07 GMT</pubDate> </item> <item> <title>[Silverlight]DataGrid整合DatePicker與ComboBox的應用</title> <link>http://www.dotblogs.com.tw/puma/archive/2008/12/04/6178.aspx</link> <pubDate>Wed, 03 Dec 2008 08:42:30 GMT</pubDate> </item> </channel> </rss>

crossdomain.xml

<?xml version="1.0"?> <!DOCTYPE cross-domain-policy SYSTEM "http://www.macromedia.com/xml/dtds/cross-domain-policy.dtd"> <cross-domain-policy> <allow-http-request-headers-from domain="*" headers="*"/> </cross-domain-policy>

執行結果:

ps.寫這篇文章遇到很多問題,可能對Silverlight還不太熟,請多多指教呀..