sl3中已经把过去的asp.net silverlight控制删除了，所以无法通过在aspx页里直接用silverlight控件在后台动态输入参数给xap文件。
解决办法如下：
1.在展示页中我使用了一个asp.net的Literal控件，此控件可以承载html代码。请注意<asp:Literal部分，代码如下:
1: <div id="silverlightControlHost">
2: <object data="data:application/x-silverlight-2," type="application/x-silverlight-2" width="100%" height="100%">
3: <param name="source" value="ClientBin/SilverlightApplication18.xap"/>
4: <param name="onError" value="onSilverlightError" />
5: <param name="background" value="white" />
6: <param name="minRuntimeVersion" value="3.0.40624.0" />
7: <param name="autoUpgrade" value="true" />
8: <asp:Literal ID="ParamInitParams" runat="server"></asp:Literal>
9: <a href="http://go.microsoft.com/fwlink/?LinkID=149156&v=3.0.40624.0" style="text-decoration:none">
10: <img src="http://go.microsoft.com/fwlink/?LinkId=108181" alt="Get Microsoft Silverlight" style="border-style:none"/>
11: </a>
12: </object><iframe id="_sl_historyFrame" style="visibility:hidden;height:0px;0px;border:0px"></iframe></div>
13: </div>
2.为了测试，我们必须在后台做一下输入InitParamsn参数的动作。这里我输入了一个名字id的参数，它的值为jac,代码如下：
1: protected void Page_Load(object sender, EventArgs e)
2: {
3: if (!IsPostBack)
4: {
5: ParamInitParams.Text =
String.Format(@"<param name=""InitParams"" value=""{0}"" />", "id=jac");
6: }
7: }
3.现在到sl里如何接收InitParams参数了，在silverlight项目里我们要在app.xaml.cs里定义前取得InitParams参数:
1: internal IDictionary<string, string> getdata;
2: private void Application_Startup(object sender, StartupEventArgs e)
3: {
4: this.RootVisual = new MainPage();
5: getdata = e.InitParams;
6: }
4.为了测试sl里是否正确接收到InitParams，我们在Mainpage.xaml.cs里作一下显示的动作：
1: public MainPage()
2: {
3: InitializeComponent();
4: Loaded += new RoutedEventHandler(MainPage_Loaded);
5: }
6:
7: void MainPage_Loaded(object sender, RoutedEventArgs e)
8: {
9: App myapp = (App)App.Current;
10: MessageBox.Show(myapp.getdata.First().Key + ":" + myapp.getdata.First().Value);
11: }