silverlight与javascript交互操作

在silverlight开发中，我们可以使用js来调用silverlight中的方法（当然方法上要捆绑相应属性），也可以将指定
的js方法绑定到silverlight应用中的事件上．本DEMO演示了通过js调用完成silverlight数据列表控件(DataGrid)的数
据绑定操作，并通过DataGrid的EmployeeList_BeginningCellEdit事件将当前选取的数据行信息返回到js所绑定的
事件参数上，并调用该js方法显示选中数据行信息，如下图所示:

           
  
     下面介绍一下主要的开发过程:)
  
     首先，我们需要建立一个Silverlight Application ，名称为：Silverlight_JS_call.
  
     然后我们要在当前的项目中加入一个类文件，名称为：EmployeeInfo.cs.
  
     下面是相应的代码，相关内容见注释:  

 

[ScriptableType]
public class EmployeeInfo
{
    /// <summary>
    /// 雇员编号
    /// </summary>
     [ScriptableMember]
    public int EmployeeNo { get; set; }
    /// <summary>
    /// 雇员名称
    /// </summary>
     [ScriptableMember]
    public string EmployeeName { get; set; }
    /// <summary>
    /// 地址
    /// </summary>
     [ScriptableMember]
    public string Address { get; set; }
}
/// <summary>
/// 雇员事件参数（用于完成与js绑定事件参数）
/// </summary>
[ScriptableType]
public class EmployeeInfoEventArgs : EventArgs
{
     [ScriptableMember]
    public EmployeeInfo employeeInfo{ get; set; }
}

/// <summary>
/// 要注册并在页面中使用的js调用脚本对象
/// </summary>
[ScriptableType]
public class JavaScriptableObject
{
    /// <summary>
    /// js捆绑的事件handler
    /// </summary>
     [ScriptableMember]
    public event EventHandler<EmployeeInfoEventArgs> SelectEmployeeInfo;

    public void OnSelectEmployeeInfo(EmployeeInfo employeeinfo)
     {
        if (SelectEmployeeInfo != null)
         {
             SelectEmployeeInfo(this, new EmployeeInfoEventArgs()
             {
                 employeeInfo = employeeinfo
             });
         }
     }
}

/// <summary>
/// 雇员信息管理类
/// </summary>
public class EmployeeManager
{
    public IEnumerable<EmployeeInfo> employeeList;
    /// <summary>
    /// 初始化会员数据
    /// </summary>
    public EmployeeManager()
     {
        //初始化雇员数据
         employeeList = new List<EmployeeInfo>()
         {
            new EmployeeInfo(){EmployeeNo = 10001, EmployeeName = "张三" , Address = "北京"},
            new EmployeeInfo(){EmployeeNo = 10002, EmployeeName = "李四" , Address = "北京"},
            new EmployeeInfo(){EmployeeNo = 10003, EmployeeName = "王五" , Address = "北京"},
            new EmployeeInfo(){EmployeeNo = 10004, EmployeeName = "马六" , Address = "北京"},
            new EmployeeInfo(){EmployeeNo = 10005, EmployeeName = "王大麻子" , Address = "北京"},
            new EmployeeInfo(){EmployeeNo = 10006, EmployeeName = "王宝强" , Address = "北京"},
            new EmployeeInfo(){EmployeeNo = 10007, EmployeeName = "王蛋蛋" , Address = "北京"},
            new EmployeeInfo(){EmployeeNo = 10008, EmployeeName = "王五强" , Address = "北京"}
         };
     }

    /// <summary>
    /// 获取指定数量的雇员数据
    /// </summary>
    /// <param name="count">要获取的雇员信息数</param>
    /// <returns></returns>    
    public IEnumerable<EmployeeInfo> GetEmployeeList(int count)
     {
        return (from e in employeeList
                     select new EmployeeInfo
                     {
                         EmployeeNo = e.EmployeeNo,
                         EmployeeName = e.EmployeeName,
                         Address = e.Address

                     }).Take(count);
     }
}

    上面代码中要注意的是[ScriptableType]和[ScriptableMember],前者允许Silverlight把类型暴露给脚本，后者
则会把成员方法或属性暴露给脚本．

　　而下面的代码就是page.xaml中的内容：　　

 

<UserControl xmlns:my="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Data"   x:Class="Silverlight_JS_call.Page"
     xmlns="http://schemas.microsoft.com/client/2007"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     Width="400" Height="300">
    <Grid x:Name="LayoutRoot" Background="White">
        <Grid.RowDefinitions>
            <RowDefinition Height="300" />
        </Grid.RowDefinitions>
        <my:DataGrid  x:Name="EmployeeList"   Grid.Row="1"   AutoGenerateColumns="True" Height="280" Margin="5,5,5,5" AlternatingRowBackground="AliceBlue" RowBackground="BlanchedAlmond">
        </my:DataGrid>
   </Grid>
</UserControl>

　　下面则是相应的page.xaml.cs文件的内容（相关内容见注释）:　　

[ScriptableType]
public partial class Page : UserControl
{
    public Page()
     {
         InitializeComponent();
        this.Loaded += Page_Loaded;
        this.EmployeeList.BeginningCellEdit +=new EventHandler<DataGridCellEditingCancelEventArgs>(EmployeeList_BeginningCellEdit);
     }
    
     
    void Page_Loaded(object sender, RoutedEventArgs e)
     {
         javaScriptableObject = new JavaScriptableObject();
        //注册js可用的类型（详情见Silverlight_JS_callTestPage.aspx中的js代码）
         HtmlPage.RegisterScriptableObject("EmployeeObject", javaScriptableObject);
         HtmlPage.RegisterScriptableObject("Page", this);
     }
    
    /// <summary>
    /// 击编辑雇员列表信息事件
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    void EmployeeList_BeginningCellEdit(object sender, DataGridCellEditingCancelEventArgs e)
     {
        //当有要编辑的信息时
        if (EmployeeList.SelectedItem != null)
         {
             EmployeeInfo employeeInfo = EmployeeList.SelectedItem as EmployeeInfo;
            //执行选中信息事件操作(最终会执行js所绑定的function代码)
             javaScriptableObject.OnSelectEmployeeInfo(employeeInfo);
         }
     }     

　　//这里必须声明是public,否则js调用该方法时会报错
     [ScriptableMember]
    public void LoadData(int count)
     {
        //加载指定数据的雇员信息
         EmployeeList.ItemsSource = new EmployeeManager().GetEmployeeList(count);
     }

     JavaScriptableObject javaScriptableObject;       
}

    上面代码要注意的是RegisterScriptableObject方法的调用，它用来注册可被脚本使用的对象实例，
与它相对应的还有一个方法RegisterCreateableType，它用于注册可被脚本使用的类型．

　　到这里，基本上完成的cs代码的开发工作．下面则是相应的js调用以及事件绑定代码了，请看：

<script type="text/javascript">
   //显示选取的雇员信息
   //注:args为cs中的EmployeeInfoEventArgs类型实例
   function ShowSelectEmployeeInfo(sender, args)
    {  
       $get("employeeNo").value = args.employeeInfo.EmployeeNo;
       $get("employeeName").value = args.employeeInfo.EmployeeName;
       $get("employeeAddress").value = args.employeeInfo.Address;
       $get("results").style.display = 'block';
    }
   
   //初始化操作，绑定到input元素（＂加载数据＂）的click事件上,详情参见aspx文件
   function Init(obj)
    {
       //绑定上面的js函数到silverlight的事件handler
        $get("Xaml1").content.EmployeeObject.SelectEmployeeInfo = ShowSelectEmployeeInfo;
       
       //加载雇员信息     
        $get("Xaml1").content.Page.LoadData(parseInt(obj.title));              
    }
</script>

           
    另外在进行初始化操作，这里使用了onclick方法来执行操作，而不是直接运行相应代码．原因是
silverlight对象加载是使用了异步方式，这样会造成对象实例化完成时间迟于页面JS脚本的运行时间．
这样设计的原因，我个人认为主要是UE方面的考虑．而这时如果脚本中直接调用对象实例化的属性或
方法时，会出现对象未知的情况．