Silverlight 2 Beta 2的Isolated Storage

Silverlight beta 2 的配置有一个重大变化就是对DRM 和Application Storage的配置

Application storage的默认大小是1M，可以通过代码修改，通过使用IsolatedStorageFile 类操作。IsolatedStorageFile 类抽象了isolated storage的虚拟文件系统 . 你创建一个 IsolatedStorageFile 类的实例, 你可以使用它对文件或文件夹进行列举或管理.同样你还可以使用该类的 IsolatedStorageFileStream 对象来管理文件内容.

虚拟文件系统根目录是对于每个机器当前登陆用户不同的, 它是一个隐藏的文件夹,存在于物理文件系统中. 每个application的不同标识将会使其映射到不同的文件夹中, 也就是说,将分配给每个不同的application 一个属于它的虚拟文件系统. .NET Framework version 2.0中的文件夹节构和隐藏架构同样在 .NET Framework for Silverlight中也用到了.

var store = IsolatedStorageFile.GetUserStoreForApplication()

store.CreateDirectory("MyApp1"); string subdirectory1 = System.IO.Path.Combine("MyApp1", "SubDir1"); store.CreateDirectory(subdirectory1); IsolatedStorageFileStream rootFile = store.CreateFile("InTheRoot.txt"); rootFile.Close(); //Write to text file string filePath = System.IO.Path.Combine(subdirectory1, "MyApp1A.txt"); try {    using (StreamWriter sw =             new StreamWriter(store.OpenFile(filePath,             FileMode.Open, FileAccess.Write)))             {                 sw.WriteLine("To do list:");                 sw.WriteLine("1. Buy supplies.");              } } catch (IsolatedStorageException ex) {     sb.AppendLine(ex.Message); } //Read from text file try {     using (StreamReader reader =         new StreamReader(store.OpenFile(filePath,             FileMode.Open, FileAccess.Read)))     {         string contents = reader.ReadToEnd();         sb.AppendLine(filePath + " contents:");         sb.AppendLine(contents);     } } catch (IsolatedStorageException ex) {     sb.AppendLine(ex.Message); } 使用Application storage存储数据，要使用IsolatedStorageSettings.ApplicationSettings

private IsolatedStorageSettings appSettings = IsolatedStorageSettings.ApplicationSettings;

现在可以用它来读取，修改、删除应用程序配置:

//Add new appSetting appSettings.Add("email", "alexg@sela.co.il"); //Read appSetting string mailAddress = (string)appSettings["email"]; //Change existing appSetting appSettings["email"] = "alex@somemail.com"; //and finally delete it... appSettings.Remove("email"); 关于存储的更详细内容，可参看的 在silverlight中使用IsolateStore隔离存储(上) 在silverlight中使用IsolateStore隔离存储(下) 可以通过代码去调整存储空间的大小，使用的API是IncreaseQuotaTo()函数。 代码如下：

using (var store = IsolatedStorageFile.GetUserStoreForApplication()) {     // Request 5MB more space in bytes.     Int64 spaceToAdd = 5242880;     Int64 curAvail = store.AvailableFreeSpace;

    // If available space is less than     // what is requested, try to increase.     if (curAvail < spaceToAdd)     {

        // Request more quota space.         if (!store.IncreaseQuotaTo(store.Quota + spaceToAdd))         {             // The user clicked NO to the             // host's prompt to approve the quota increase.             tbResults.Text = "User declined to approve Quota inrease";         }         else         {             // The user clicked YES to the             // host's prompt to approve the quota increase.             tbResults.Text = "Quota inreased";         }     } }

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