Silverlight DataBindings for 1.1 (Managed code)

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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, 0, 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(), 0, (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

<Canvasx: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"

<CanvasName="DataDemo"Height="600"Width="800"

Tag="BindingContext:Default.aspx,GetData,GetCount">

<Canvas.Background>

<GradientStopColor="Yellow"Offset="0.0" />

<GradientStopColor="Orange"Offset="0.5" />

<GradientStopColor="Red"Offset="1.0" />

LinearGradientBrush>

Canvas.Background>

<TextBlockTag="BindingField:EmployeeID;BindingProperty:Text"

Name="txtEmployeeID"Width="144"Height="24"Canvas.Left="166"

Canvas.Top="23"Text="A00001"TextWrapping="Wrap"/>

<TextBlockTag="BindingField:LastName;BindingProperty:Text"

Name="txtLastName"Width="320"Height="24"Canvas.Left="500"

Canvas.Top="23"Text="Alean Company"TextWrapping="Wrap"/>

<TextBlockTag="BindingField:FirstName;BindingProperty:Text"Name="txtFirstName"

Width="320"Height="24"Canvas.Left="166"Canvas.Top="72"

Text="Jeffray"TextWrapping="Wrap"/>

<TextBlockTag="BindingField:Title;BindingProperty:Text"

Name="txtTitle"Width="576"Height="24"Canvas.Left="166"

Canvas.Top="122"Text="Taipen 101"TextWrapping="Wrap"/>

<TextBlockTag="BindingField:HireDate;BindingProperty:Text"Name="txtHireDate"

Width="576"Height="24"Canvas.Left="166"Canvas.Top="171"

Text="2005/3/4"TextWrapping="Wrap"/>

<ImageName="imgPhoto"

Tag="BindingField:EmployeeID;BindingProperty:Source;Format:Default.aspx?ID={0}"

Width="357"Height="206"Canvas.Left="400"Canvas.Top="301">

<Image.Triggers>

<EventTriggerRoutedEvent="Image.Loaded">

<StoryboardName="imgAnimation">

<DoubleAnimation

Storyboard.TargetName="imgPhoto"

Storyboard.TargetProperty="Opacity"

From="0.0"To="1.0"Duration="0:0:6"/>

Storyboard>

BeginStoryboard>

EventTrigger>

Image.Triggers>

Image>

<TextBlockName="txtLabel1"Width="114"Height="24"Canvas.Left="18"

Canvas.Top="23"Text="Employee ID:"TextWrapping="Wrap"/>

<TextBlockName="txtLabel1_Copy"Width="120"Height="24"Canvas.Left="349"

Canvas.Top="23"Text="Last Name:"TextWrapping="Wrap"/>

<TextBlockName="txtLabel1_Copy1"Width="130"Height="24"Canvas.Left="18"

Canvas.Top="72"Text="First Name:"TextWrapping="Wrap"/>

<TextBlockName="txtLabel1_Copy2"Width="104"Height="24"Canvas.Left="18"

Canvas.Top="122"Text="Title :"TextWrapping="Wrap"/>

<TextBlockName="txtLabel1_Copy3"Width="93"Height="24"Canvas.Left="18"

Canvas.Top="171"Text="Hire Date:"TextWrapping="Wrap"/>

Canvas>

<TextBlockCanvas.Left="100"Canvas.Top="200"

Text="Prev"MouseLeftButtonDown="OnPrevClick"/>

<TextBlockCanvas.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)

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