Silverlight 3动态加载DLL及其中的类型

1.  采用Isolated Storage存储DLL文件，在此存储位置的文件是Silverlight可以访问的，并且针对当前用户和所对应的xap文件（网址）是唯一的。采用这种方式可以只在用户第一次访问时下载一次，提升用户使用体验。（示例代码采用复制本地文件到Isolated Storage的方式，也可以用WebClient从服务器上获取）

 1         private static void LoadLocalFiles(TextBox slt)
 2         {
 3             OpenFileDialog ofd = new OpenFileDialog();
 4             ofd.Filter = "DLL Files (*.dll)|*.dll";
 5             ofd.Multiselect = true;
 6 
 7             if (ofd.ShowDialog() == true)
 8             {
 9                 using (IsolatedStorageFile store = IsolatedStorageFile.GetUserStoreForApplication())
                 {
                     foreach (FileInfo file in ofd.Files)
                     {
                         if (store.FileExists(file.Name) == true)
                         {
                             slt.Text = "File " + file.Name + "existed";
                             return;
                         }
                         else
                         {
                             using (Stream fileStream = file.OpenRead())
                             {
                                 if (fileStream.Length > store.AvailableFreeSpace)
                                 {
                                     if (store.IncreaseQuotaTo(store.Quota + fileStream.Length) == true)
                                     {
                                         slt.Text = "Quota increase succeeded";
                                     }
                                     else
                                     {
                                         slt.Text = "Quota increase failed";
                                         return;
                                     }
                                 }
 
                                 using (IsolatedStorageFileStream storeStream = store.CreateFile(file.Name))
                                 {
                                     byte[] buffer = new byte[1024];
                                     int count = 0;
 
                                     do
                                     {
                                         count = fileStream.Read(buffer, 0, buffer.Length);
 
                                         if (count > 0)
                                         {
                                             storeStream.Write(buffer, 0, count);
                                         }
                                     } while (count > 0);
                                 }
                             }
                         }
                     }
                 }
             }
         }
 

 

2.  采用Assembly加载DLL文件。

 1         void btnDemo_Click(object sender, RoutedEventArgs e)
 2         {
 3             try
 4             {
 5                 using (IsolatedStorageFile store = IsolatedStorageFile.GetUserStoreForApplication())
 6                 {
 7                     string dllToLoad = "SCLTextBox.dll";
 8                     if (store.FileExists(dllToLoad) == true)
 9                     {
                         using (IsolatedStorageFileStream stream = store.OpenFile(dllToLoad, FileMode.Open))
                         {
                             AssemblyPart assemblyPart = new AssemblyPart();
                             Assembly asm = assemblyPart.Load(stream);
                             Control ctrl = asm.CreateInstance("SCLTextBox.SLTextBox") as Control;
                             ctrl.Height = 100;
                             ctrl.Width = 100;
                             ctrl.BorderThickness = new Thickness(2, 4, 6, 9);
                             if (ctrl != null)
                             {
                                 Canvas.SetLeft(ctrl, 300);
                                 Canvas.SetTop(ctrl, 500);
 
                                 LayoutRoot.Children.Add(ctrl);
                             }
                         }
                     }
                 }
             }
             catch (Exception ex)
             {
                 TextBox slt = new TextBox();
                 slt.Height = 40;
                 slt.Width = 200;
                 slt.Text = ex.Message;
                 Canvas.SetLeft(slt, 20);
                 Canvas.SetTop(slt, 300);
                 this.LayoutRoot.Children.Add(slt);
             }