Silverlight DataBindings for 1.1 (Managed code)

概述  Silverlight DataBindings for 1.1 (Managed code)     文 / 黃忠成      RC1方興未艾， RC2已在路上了，看來1.0 Release之日不遠了！前面一篇文章利用了PageMethods與JavaScript為Silverlight 1.0RC加上DataBindings的功能，此次舞台換到了Silverlight 1.1 Alpha   Silverlight DataBindings for 1.1 (Managed code)     文 / 黃忠成      RC1方興未艾， RC2已在路上了，看來1.0 Release之日不遠了！前面一篇文章利用了PageMethods與JavaScript為Silverlight 1.0RC加上DataBindings的功能，此次舞台換到了Silverlight 1.1 Alpha Refresh及Visual Studio 2008 Beta 2上，與1.1時不同，這次已無法用單一的Web Site模式實作，基於ASP.NET AJAX與Silverlight所使用的CLR Runtime不同，我們必須將Silverlight與ASP.NET AJAX拆開，別誤會！這並非意味你無法將Silverlight與ASP.NET AJAX放在同一個虛擬目錄下，Silverlight 1.1使用的Binary目錄是ClIEntBin，ASP.NET是Bin，兩者並無衝突，限制只在於你必須將Silverlight與ASP.NET AJAX分成兩個Project來編譯，在Silverlight編譯完成後將.xaml、.Js複製到ASP.NET AJAX的專案目錄下，再將.dll複製到ASP.NET AJAX的ClIEntBin目錄下即可。回到主題，在Silverlight 1.1中，實現Data Bindings除了可以用前一篇文章的JavaScript技巧外，還多了一個選擇，那就是使用C#等Managed的語言，SLDH.Js的C#版本如下。   SLDH.cs

///////////////////////////////////////////////////////////////////////// // Silverlight Data Binding Helper 0.1 for Silverlight 1.1 Alpha Refresh ///////////////////////////////////////////////////////////////////////// using System; using System.Text; using System.IO; using System.Net; using System.Reflection; using System.linq; using System.Collections.Generic; using System.windows; using System.windows.Controls; using System.windows.documents; using System.windows.Ink; using System.windows.input; using System.windows.Media; using System.windows.Media.Animation; using System.windows.Shapes; using System.windows.browser.Net; using System.windows.browser.Serialization;   namespace SilverlightDataHelper {     public class JsONDaTarow     {         private List<object> _columns;         private List<object> _values;           public object this[int index]         {             get             {                 return _values[index];             }         }           public object this[string name]         {             get             {                 for (int i = 0; i < _columns.Count; i++)                 {                     if (((string)_columns[i]).Equals(name))                         return _values[i];                 }                 return null;             }         }           internal JsONDaTarow(object[] columns,object[] values)         {             _columns = new List<object>(columns);             _values = new List<object>(values);         }     }       public class BindingData     {         private bool _bindingComplete = false;         private string _bindingProperty = string.Empty;         private string _bindingFIEld = string.Empty;         private FrameworkElement _control;         private string _format = string.Empty;         private PropertyInfo _cachedProp = null;           public bool BindingComplete         {             get             {                 return this._bindingComplete;             }         }           public string BindingProperty         {             get             {                 return _bindingProperty;             }         }           public string BindingFIEld         {             get             {                 return _bindingFIEld;             }         }           public FrameworkElement Control         {             get             {                 return _control;             }         }           public string Format         {             get             {                 return _format;             }             set             {                 _format = value;             }         }           public voID UpdateValue(JsONDaTarow dataItem)         {             if (_bindingComplete)             {                 if (_cachedProp == null)                 {                     _cachedProp = _control.GetType().GetProperty(_bindingProperty);                     if (_cachedProp == null)                         _bindingComplete = false;                 }                 if (_cachedProp != null && Format != string.Empty)                 {                     if (_cachedProp.PropertyType == typeof(Uri))                     {                         Uri uri = new Uri(string.Format(Format,                                dataItem[BindingFIEld]),UriKind.relative);                         _cachedProp.SetValue(_control,uri,null);                     }                     else                         _cachedProp.SetValue(_control,string.Format(Format, dataItem[BindingFIEld]),null);                 }                 else if (_cachedProp != null)                     _cachedProp.SetValue(_control,dataItem[BindingFIEld],null);             }         }           public BindingData(FrameworkElement ctrl,string bindingExpression)         {             string[] bindings = bindingExpression.Split(';');             _bindingComplete = false;             _control = ctrl;             for (int i = 0; i < bindings.Length; i++)             {                 string[] temp = bindings[i].Split(':');                 if (temp.Length != 2)                 {                     _bindingComplete = false;                     return;                 }                 if (temp[0].Tolower() == "bindingfIEld")                     _bindingFIEld = temp[1];                 else if (temp[0].Tolower() == "bindingproperty")                     _bindingProperty = temp[1];                 else if (temp[0].Tolower() == "format")                     _format = temp[1];             }             if (_bindingFIEld != string.Empty &&                _bindingProperty != string.Empty)                 _bindingComplete = true;         }     }       public class BindingContext     {         private Panel _container;         private List<BindingData> _bindingControls = null;         private bool _bindingComplete = false;         private int _position = 0;         private int _count = -1;         private string _serviceUrl = string.Empty;         private string _bindingMethod = string.Empty;         private string _bindingCountMethod = string.Empty;         private string _countMethod = string.Empty;             public int position         {             get             {                 return _position;             }             set             {                 if (_position != value && value < Count && value >= 0)                 {                     _position = value;                     UpdateBinding();                 }             }         }           public int Count         {             get             {                 return _count;             }         }           public bool BindingComplete         {             get             {                 return _bindingComplete;             }         }           public List<BindingData> BindingControls         {             get             {                 if (_bindingControls == null)                     _bindingControls = new List<BindingData>();                 return _bindingControls;             }         }           private voID ChilDWorker(FrameworkElement elem)         {             string expRSSsion = elem.Tag == null ? string.Empty : elem.Tag;             BindingData data = new BindingData(elem,expRSSsion);             if (data.BindingComplete)                 BindingControls.Add(data);             if (elem is Panel)             {                 Panel pnl = (Panel)elem;                 for (int i = 0; i < pnl.Children.Count; i++)                 {                     if (pnl.Children[i] is FrameworkElement)                         ChilDWorker((FrameworkElement)pnl.Children[i]);                 }             }         }           private voID FetchCount()         {             browserhttpWebRequest request =                     new browserhttpWebRequest(new Uri(_serviceUrl + "/" +                                               _bindingCountMethod,UriKind.relative));             request.ContentType = "application/Json; charset=utf-8";             request.Method = "POST";             request.ContentLength = 0;             request.Referer = System.windows.browser.HTMLPage.documentUri.absolutePath;             request.Accept = "/*/";             httpWebResponse response = request.GetResponse();             StreamReader sr = new StreamReader(response.GetResponseStream());             JavaScriptSerializer serializer = new JavaScriptSerializer();             string data = sr.ReadToEnd();             _count = serializer.Deserialize<int>(data);             sr.Close();             response.Close();             request.Close();         }           private JsONDaTarow FetchData(int index)         {             browserhttpWebRequest request =                 new browserhttpWebRequest(new Uri(_serviceUrl + "/" +                                           _bindingMethod,UriKind.relative));             JavaScriptSerializer serializer = new JavaScriptSerializer();             request.ContentType = "application/Json; charset=utf-8";             request.Method = "POST";             request.Referer = System.windows.browser.HTMLPage.documentUri.absolutePath;             request.Accept = "/*/";             Stream reqStream = request.GetRequestStream();             byte[] buff = EnCoding.UTF8.GetBytes("{index:" + index.ToString() + "}");             reqStream.Write(buff,buff.Length);             request.ContentLength = buff.Length;             httpWebResponse response = request.GetResponse();             StreamReader sr = new StreamReader(response.GetResponseStream());             string data = sr.ReadToEnd();             sr.Close();             response.Close();             request.Close();             object[] parsedData = serializer.Deserialize<object[]>(data);             return new JsONDaTarow((object[])parsedData[0],(object[])parsedData[1]);           }           private voID UpdateBinding()         {             JsONDaTarow row = FetchData(position);             foreach (BindingData item in BindingControls)                 item.UpdateValue(row);         }           public voID Initialize()         {             ChilDWorker(_container);             FetchCount();             UpdateBinding();         }           public BindingContext(Panel container)         {             _container = container;             if (_container.Tag == null)             {                 _bindingComplete = false;                 return;             }             string[] parseBinding = container.Tag.Split(':');             _bindingComplete = false;             if (parseBinding.Length == 2 && parseBinding[0].Tolower() == "bindingcontext")             {                 string[] bindingMethods = parseBinding[1].Split(',');                 if (bindingMethods.Length == 3)                 {                     _serviceUrl = bindingMethods[0];                     _bindingMethod = bindingMethods[1];                     _bindingCountMethod = bindingMethods[2];                     _bindingComplete = true;                 }             }             if (_bindingComplete)                 ChilDWorker(container);         }     } }

ㄟ...程式碼變長了哦~~~ >"<，在某些情況下，Managed Code不見得比JavaScript簡單吧！只是別忘了，這些程式碼是預先編譯後再下載到客戶端，由Silverlight CLR執行的，就理論上來說，執行效率應該比JavaScript好才對。由於Managed SLDH使用了另一種JsON格式來交換資料，所以.aspx.cs也要做一些調整。 Default.aspx.cs

using System; using System.IO; using System.Data; using System.Collections.Generic; using System.Data.sqlClIEnt; using System.Configuration; using System.linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HTMLControls; using System.Xml.linq; using System.Web.Services;   public partial class _Default : System.Web.UI.Page {     private static Datatable BuildDataCache()     {         if (httpRuntime.Cache["DataCache_Employees"] != null)             return httpRuntime.Cache["DataCache_Employees"] as Datatable;         else         {             using (sqlConnection conn = new sqlConnection(ConfigurationManager.ConnectionStrings[" ConnectionString" ].ConnectionString))             {                 sqlDataAdapter adapter = new sqlDataAdapter( "SELECT * FROM Employees ORDER BY EmployeeID" ,conn);                 Datatable table = new Datatable("Employees");                 adapter.Fill(table);                 httpRuntime.Cache["DataCache_Employees"] = table;                 return table;             }         }     }       private static List<object> BuildJsONRow(DaTarow row)     {         List<object> result = new List<object>();         List<string> columns = new List<string>();         List<object> values = new List<object>();         foreach (DataColumn col in row.table.Columns)         {             columns.Add(col.Columnname);             values.Add(row.IsNull(col) ? string.Empty : row[col].ToString());         }         result.Add(columns);         result.Add(values);         return result;     }       [WebMethod]     public static List<object> GetData(int index)     {         Datatable table = BuildDataCache();         return BuildJsONRow(table.defaultview[index].Row);     }       [WebMethod]     public static int GetCount()     {         Datatable table = BuildDataCache();         return table.defaultview.Count;     }       protected voID Page_Load(object sender,EventArgs e)     {         if (Request.queryString["ID"] != null &&            Request.queryString["ID"].Length > 0)         {             using (sqlConnection conn = new sqlConnection(ConfigurationManager.ConnectionStrings[ "ConnectionString" ].ConnectionString))             {                 conn.open();                 sqlCommand cmd = new sqlCommand( "SELECT Photo FROM Employees WHERE EmployeeID = @ID" ,conn);                 cmd.Parameters.AdDWithValue("@ID",Request.queryString["ID"]);                 object data = cmd.ExecuteScalar();                 if (data != null && ((byte[])data).Length > 0)                 {                     Response.Clear();                     Response.BufferOutput = true;                     Response.ContentType = "image/jpeg";                     MemoryStream ms = new MemoryStream();                     ms.Write(((byte[])data),78,((byte[])data).Length - 78);                     MemoryStream jpegms = new MemoryStream();                     System.Drawing.Image.FromStream(ms).Save(jpegms, System.Drawing.Imaging.ImageFormat.Jpeg);                     jpegms.position = 0;                     Response.OutputStream.Write(jpegms.GetBuffer(),(int)jpegms.Length);                     ms.dispose();                     jpegms.dispose();                     Response.Flush();                     Response.End();                 }             }         }     } }

當需要做DataBindings時，只需要在.xaml.cs的Page_Loaded事件處理函式中建立此物件即可，見下面程式碼。   Page.xaml

< Canvas x:name = "parentCanvas"         xmlns = "http://schemas.microsoft.com/clIEnt/2007"         xmlns:x = "http://schemas.microsoft.com/winfx/2006/xaml"         Loaded = "Page_Loaded"         x:Class = "SilverlightProject1.Page;assembly=ClIEntBin/SilverlightProject1.dll"         WIDth = "640"         Height = "480"         Background = "White"         >            < Canvas name = "DataDemo"Height="600"WIDth="800"   Tag = "BindingContext:Default.aspx,GetData,GetCount">                      < Canvas.Background >                                 < linearGradIEntBrush >                                            < GradIEntStop color = "Yellow"Offset="0.0" />                                            < GradIEntStop color = "Orange"Offset="0.5" />                                            < GradIEntStop color = "Red"Offset="1.0" />                                 </ linearGradIEntBrush >                      </ Canvas.Background >            < TextBlock Tag = "BindingFIEld:EmployeeID;BindingProperty:Text"           name = "txtEmployeeID"WIDth="144"Height="24"Canvas.left="166"         Canvas.top = "23"Text="A00001"textwrapPing="Wrap"/>                      < TextBlock Tag = "BindingFIEld:Lastname;BindingProperty:Text"             name = "txtLastname"WIDth="320"Height="24"Canvas.left="500"           Canvas.top = "23"Text="Alean Company"textwrapPing="Wrap"/>                      < TextBlock Tag = "BindingFIEld:Firstname;BindingProperty:Text"name="txtFirstname"                       WIDth = "320"Height="24"Canvas.left="166"Canvas.top="72"                       Text = "Jeffray"textwrapPing="Wrap"/>                      < TextBlock Tag = "BindingFIEld:Title;BindingProperty:Text"                       name = "txtTitle"WIDth="576"Height="24"Canvas.left="166"                       Canvas.top = "122"Text="Taipen 101"textwrapPing="Wrap"/>                      < TextBlock Tag = "BindingFIEld:HireDate;BindingProperty:Text"name="txtHireDate"                       WIDth = "576"Height="24"Canvas.left="166"Canvas.top="171"                       Text = "2005/3/4"textwrapPing="Wrap"/>                      < Image name = "imgPhoto"  Tag = "BindingFIEld:EmployeeID;BindingProperty:Source;Format:Default.aspx?ID={0}"        WIDth = "357"Height="206"Canvas.left="400"Canvas.top="301">                                 < Image.Triggers >                                            < EventTrigger RoutedEvent = "Image.Loaded">                                                      < BeginStoryboard >                                                                 < Storyboard name = "imgAnimation">                                                                            < DoubleAnimation                                                                            Storyboard.Targetname = "imgPhoto"                                                                            Storyboard.TargetProperty = "Opacity"                                                                            From = "0.0"To="1.0"Duration="0:0:6"/>                                                                 </ Storyboard >                                                      </ BeginStoryboard >                                            </ EventTrigger >                                 </ Image.Triggers >                      </ Image >                      < TextBlock name = "txtLabel1"WIDth="114"Height="24"Canvas.left="18"            Canvas.top = "23"Text="Employee ID:"textwrapPing="Wrap"/>                      < TextBlock name = "txtLabel1_copy"WIDth="120"Height="24"Canvas.left="349"              Canvas.top = "23"Text="Last name:"textwrapPing="Wrap"/>                      < TextBlock name = "txtLabel1_copy1"WIDth="130"Height="24"Canvas.left="18"              Canvas.top = "72"Text="First name:"textwrapPing="Wrap"/>                      < TextBlock name = "txtLabel1_copy2"WIDth="104"Height="24"Canvas.left="18"            Canvas.top = "122"Text="Title :"textwrapPing="Wrap"/>                      < TextBlock name = "txtLabel1_copy3"WIDth="93"Height="24"Canvas.left="18"              Canvas.top = "171"Text="Hire Date:"textwrapPing="Wrap"/>            </ Canvas >            < TextBlock Canvas.left = "100"Canvas.top="200" Text = "Prev"MouseleftbuttonDown="OnPrevClick"/>            < TextBlock Canvas.left = "150"Canvas.top="200" Text = "Next"MouseleftbuttonDown="OnNextClick"/> </ Canvas >

  Page.xaml.cs

using System; using System.linq; using System.Collections.Generic; using System.windows; using System.windows.Controls; using System.windows.documents; using System.windows.Ink; using System.windows.input; using System.windows.Media; using System.windows.Media.Animation; using System.windows.Shapes;   namespace SilverlightProject1 {     public partial class Page : Canvas     {         private SilverlightDataHelper.BindingContext _context = null;         public voID Page_Loaded(object o,EventArgs e)         {             // required to initialize variables             InitializeComponent();             _context = new SilverlightDataHelper.BindingContext(Findname("DataDemo") as Panel);             _context.Initialize();         }           voID OnPrevClick(object sender,EventArgs args)         {             if (_context.position > 0)             {                 _context.position--;                 ((Storyboard)Findname("imgAnimation")).Begin();             }         }           voID OnNextClick(object sender,EventArgs args)         {             if (_context.position < _context.Count)             {                 _context.position++;                 ((Storyboard)Findname("imgAnimation")).Begin();             }         }     } }

下圖是執行畫面。

  http://www.dreams.idv.tw/~code6421/files/SLDataDemo_11.zip (你需要將northwind.mdf、northwind_log.ldf複製到App_Data目錄下，或是修改web.config中的ConnectionString來連結到北風資料庫)   总结

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