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IsolatedStorageFileStream Class

Exposes a file within isolated storage.

Namespace:  System.IO.IsolatedStorage
Assembly:  mscorlib (in mscorlib.dll)

[ComVisibleAttribute(true)]
public class IsolatedStorageFileStream : FileStream

Use this class to read, write and create files in isolated storage.

Since this class extends FileStream, you can use an instance of IsolatedStorageFileStream in most situations where a FileStream might otherwise be used, such as to construct a StreamReader or StreamWriter.

The following console application demonstrates how you can use IsolatedStorageFile and IsolatedStorageFileStream to write data to an Isolated Storage file. The user is requested to log in. If the user is a new user, a News URL and a Sports URL are recorded as personal preferences in Isolated Storage. If the user is a returning user, the user's current preferences are displayed. The code examples used throughout this namespace are presented in the context of this sample application. You can use the Isolated Storage Tool (Storeadm.exe) utility to list and remove the Isolated Storage files that are created with this console application.

// This sample demonstrates methods of classes found in the System.IO IsolatedStorage namespace. 
using System;
using System.IO;
using System.IO.IsolatedStorage;
using System.Security.Policy;
using Microsoft.Win32.SafeHandles;
using System.Security.Permissions;

[assembly: CLSCompliantAttribute(true)]

class ConsoleApp
{
    [STAThread]
    static void Main(string[] args)
    {

        // Prompt the user for their username.

        Console.WriteLine("Login:");

        // Does no error checking.
        LoginPrefs lp = new LoginPrefs(Console.ReadLine());

        if (lp.NewPrefs)
        {
            Console.WriteLine("Please set preferences for a new user.");
            GatherInfoFromUser(lp);

            // Write the new preferences to storage. 
            double percentUsed = lp.SetPrefsForUser();
            Console.WriteLine("Your preferences have been written. Current space used is " + percentUsed.ToString() + " %");
        }
        else
        {
            Console.WriteLine("Welcome back.");

            Console.WriteLine("Your preferences have expired, please reset them.");
            GatherInfoFromUser(lp);
            lp.SetNewPrefsForUser();

            Console.WriteLine("Your news site has been set to {0}\n and your sports site has been set to {1}.", lp.NewsUrl, lp.SportsUrl);
        }
        lp.GetIsoStoreInfo();
        Console.WriteLine("Enter 'd' to delete the IsolatedStorage files and exit, or press any other key to exit without deleting files.");
        string consoleInput = Console.ReadLine();
        if (consoleInput.ToLower() == "d")
        {
            lp.DeleteFiles();
            lp.DeleteDirectories();
        }

    }

    static void GatherInfoFromUser(LoginPrefs lp)
    {
        Console.WriteLine("Please enter the URL of your news site.");
        lp.NewsUrl = Console.ReadLine();
        Console.WriteLine("Please enter the URL of your sports site.");
        lp.SportsUrl = Console.ReadLine();
    }
}
[SecurityPermissionAttribute(SecurityAction.Demand, Flags=SecurityPermissionFlag.UnmanagedCode)]
public class LoginPrefs
{
    public LoginPrefs(string myUserName)
    {
        userName = myUserName;
        myNewPrefs = GetPrefsForUser();
    }
    string userName;

    string myNewsUrl;
    public string NewsUrl
    {
        get { return myNewsUrl; }
        set { myNewsUrl = value; }
    }

    string mySportsUrl;
    public string SportsUrl
    {
        get { return mySportsUrl; }
        set { mySportsUrl = value; }
    }
    bool myNewPrefs;
    public bool NewPrefs
    {
        get { return myNewPrefs; }
    }

    private bool GetPrefsForUser()
    {
        try
        {

            // Retrieve an IsolatedStorageFile for the current Domain and Assembly.
            IsolatedStorageFile isoFile =
                IsolatedStorageFile.GetStore(IsolatedStorageScope.User |
                IsolatedStorageScope.Assembly |
                IsolatedStorageScope.Domain,
                null,
                null);

            IsolatedStorageFileStream isoStream =
                new IsolatedStorageFileStream(this.userName,
                FileMode.Open,
                FileAccess.Read,
                FileShare.Read);

            // The code executes to this point only if a file corresponding to the username exists. 
            // Though you can perform operations on the stream, you cannot get a handle to the file. 

            try
            {

                SafeFileHandle aFileHandle = isoStream.SafeFileHandle;
                Console.WriteLine("A pointer to a file handle has been obtained. "
                    + aFileHandle.ToString() + " "
                    + aFileHandle.GetHashCode());
            }

            catch (Exception e)
            {
                // Handle the exception.
                Console.WriteLine("Expected exception");
                Console.WriteLine(e);
            }

            StreamReader reader = new StreamReader(isoStream);
            // Read the data. 
            this.NewsUrl = reader.ReadLine();
            this.SportsUrl = reader.ReadLine();
            reader.Close();
            isoFile.Close();
            return false;
        }
        catch (System.IO.FileNotFoundException)
        {
            // Expected exception if a file cannot be found. This indicates that we have a new user. 
            return true;
        }
    }
    public bool GetIsoStoreInfo()
    {
        // Get a User store with type evidence for the current Domain and the Assembly.
        IsolatedStorageFile isoFile = IsolatedStorageFile.GetStore(IsolatedStorageScope.User |
            IsolatedStorageScope.Assembly |
            IsolatedStorageScope.Domain,
            typeof(System.Security.Policy.Url),
            typeof(System.Security.Policy.Url));

        String[] dirNames = isoFile.GetDirectoryNames("*");
        String[] fileNames = isoFile.GetFileNames("*");

        // List directories currently in this Isolated Storage. 
        if (dirNames.Length > 0)
        {
            for (int i = 0; i < dirNames.Length; ++i)
            {
                Console.WriteLine("Directory Name: " + dirNames[i]);
            }
        }

        // List the files currently in this Isolated Storage. 
        // The list represents all users who have personal preferences stored for this application. 
        if (fileNames.Length > 0)
        {
            for (int i = 0; i < fileNames.Length; ++i)
            {
                Console.WriteLine("File Name: " + fileNames[i]);
            }
        }

        isoFile.Close();
        return true;
    }

    public double SetPrefsForUser()
    {
        try
        {
            IsolatedStorageFile isoFile;
            isoFile = IsolatedStorageFile.GetUserStoreForDomain();

            // Open or create a writable file.
            IsolatedStorageFileStream isoStream =
                new IsolatedStorageFileStream(this.userName,
                FileMode.OpenOrCreate,
                FileAccess.Write,
                isoFile);

            StreamWriter writer = new StreamWriter(isoStream);
            writer.WriteLine(this.NewsUrl);
            writer.WriteLine(this.SportsUrl);
            // Calculate the amount of space used to record the user's preferences. 
            double d = isoFile.CurrentSize / isoFile.MaximumSize;
            Console.WriteLine("CurrentSize = " + isoFile.CurrentSize.ToString());
            Console.WriteLine("MaximumSize = " + isoFile.MaximumSize.ToString());
            // StreamWriter.Close implicitly closes isoStream.
            writer.Close();
            isoFile.Dispose();
            isoFile.Close();
            return d;
        }
        catch (IsolatedStorageException ex)
        {
            // Add code here to handle the exception.
            Console.WriteLine(ex);
            return 0.0;
        }
    }

    public void DeleteFiles()
    {
        try
        {
            IsolatedStorageFile isoFile = IsolatedStorageFile.GetStore(IsolatedStorageScope.User |
                IsolatedStorageScope.Assembly |
                IsolatedStorageScope.Domain,
                typeof(System.Security.Policy.Url),
                typeof(System.Security.Policy.Url));

            String[] dirNames = isoFile.GetDirectoryNames("*");
            String[] fileNames = isoFile.GetFileNames("*");

            // List the files currently in this Isolated Storage. 
            // The list represents all users who have personal 
            // preferences stored for this application. 
            if (fileNames.Length > 0)
            {
                for (int i = 0; i < fileNames.Length; ++i)
                {
                    // Delete the files.
                    isoFile.DeleteFile(fileNames[i]);
                }
                // Confirm that no files remain.
                fileNames = isoFile.GetFileNames("*");
            }
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }

    }
    // This method deletes directories in the specified Isolated Storage, after first  
    // deleting the files they contain. In this example, the Archive directory is deleted.  
    // There should be no other directories in this Isolated Storage. 
    public void DeleteDirectories()
    {
        try
        {
            IsolatedStorageFile isoFile = IsolatedStorageFile.GetStore(IsolatedStorageScope.User |
                IsolatedStorageScope.Assembly |
                IsolatedStorageScope.Domain,
                typeof(System.Security.Policy.Url),
                typeof(System.Security.Policy.Url));
            String[] dirNames = isoFile.GetDirectoryNames("*");
            String[] fileNames = isoFile.GetFileNames("Archive\\*");

            // Delete all the files currently in the Archive directory. 

            if (fileNames.Length > 0)
            {
                for (int i = 0; i < fileNames.Length; ++i)
                {
                    // Delete the files.
                    isoFile.DeleteFile("Archive\\" + fileNames[i]);
                }
                // Confirm that no files remain.
                fileNames = isoFile.GetFileNames("Archive\\*");
            }


            if (dirNames.Length > 0)
            {
                for (int i = 0; i < dirNames.Length; ++i)
                {
                    // Delete the Archive directory.
                }
            }
            dirNames = isoFile.GetDirectoryNames("*");
            isoFile.Remove();
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
    }
    public double SetNewPrefsForUser()
    {
        try
        {
            byte inputChar;
            IsolatedStorageFile isoFile = IsolatedStorageFile.GetStore(IsolatedStorageScope.User |
                IsolatedStorageScope.Assembly |
                IsolatedStorageScope.Domain,
                typeof(System.Security.Policy.Url),
                typeof(System.Security.Policy.Url));

            // If this is not a new user, archive the old preferences and  
            // overwrite them using the new preferences. 
            if (!this.myNewPrefs)
            {
                if (isoFile.GetDirectoryNames("Archive").Length == 0)
                    isoFile.CreateDirectory("Archive");
                else
                {

                    IsolatedStorageFileStream source =
                        new IsolatedStorageFileStream(this.userName, FileMode.OpenOrCreate,
                        isoFile);
                    // This is the stream from which data will be read.
                    Console.WriteLine("Is the source file readable? " + (source.CanRead ? "true" : "false"));
                    Console.WriteLine("Creating new IsolatedStorageFileStream for Archive.");

                    // Open or create a writable file.
                    IsolatedStorageFileStream target =
                        new IsolatedStorageFileStream("Archive\\ " + this.userName,
                        FileMode.OpenOrCreate,
                        FileAccess.Write,
                        FileShare.Write,
                        isoFile);
                    Console.WriteLine("Is the target file writable? " + (target.CanWrite ? "true" : "false"));
                    // Stream the old file to a new file in the Archive directory. 
                    if (source.IsAsync && target.IsAsync)
                    {
                        // IsolatedStorageFileStreams cannot be asynchronous.  However, you 
                        // can use the asynchronous BeginRead and BeginWrite functions 
                        // with some possible performance penalty.

                        Console.WriteLine("IsolatedStorageFileStreams cannot be asynchronous.");
                    }

                    else
                    {
                        Console.WriteLine("Writing data to the new file.");
                        while (source.Position < source.Length)
                        {
                            inputChar = (byte)source.ReadByte();
                            target.WriteByte(inputChar);
                        }

                        // Determine the size of the IsolatedStorageFileStream 
                        // by checking its Length property.
                        Console.WriteLine("Total Bytes Read: " + source.Length);

                    }

                    // After you have read and written to the streams, close them.
                    target.Close();
                    source.Close();
                }
            }

            // Open or create a writable file with a maximum size of 10K.
            IsolatedStorageFileStream isoStream =
                new IsolatedStorageFileStream(this.userName,
                FileMode.OpenOrCreate,
                FileAccess.Write,
                FileShare.Write,
                10240,
                isoFile);
            isoStream.Position = 0;  // Position to overwrite the old data.
            StreamWriter writer = new StreamWriter(isoStream);
            // Update the data based on the new inputs.
            writer.WriteLine(this.NewsUrl);
            writer.WriteLine(this.SportsUrl);

            // Calculate the amount of space used to record this user's preferences. 
            double d = isoFile.CurrentSize / isoFile.MaximumSize;
            Console.WriteLine("CurrentSize = " + isoFile.CurrentSize.ToString());
            Console.WriteLine("MaximumSize = " + isoFile.MaximumSize.ToString());
            // StreamWriter.Close implicitly closes isoStream.
            writer.Close();
            isoFile.Close();

            return d;
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
            return 0.0;
        }
    }
}

System.Object
  System.MarshalByRefObject
    System.IO.Stream
      System.IO.FileStream
        System.IO.IsolatedStorage.IsolatedStorageFileStream

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

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