IsolatedStorageFileStream Class

Definition

Namespace:

System.IO.IsolatedStorage

Assemblies:

netstandard.dll, System.IO.IsolatedStorage.dll

Source:

IsolatedStorageFileStream.cs

Exposes a file within isolated storage.

C#

public class IsolatedStorageFileStream : System.IO.FileStream

Inheritance

Object

MarshalByRefObject

Stream

FileStream

IsolatedStorageFileStream

Examples

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 Storeadm.exe (Isolated Storage Tool) utility to list and remove the Isolated Storage files that are created with this console application.

C#

// 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;

[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();
    }
}

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("substituteUsername",
                System.IO.FileMode.Open,
                System.IO.FileAccess.Read,
                 System.IO.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;
        }
    }
}

Remarks

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.

This type implements the IDisposable interface. When you have finished using the type, you should dispose of it either directly or indirectly. To dispose of the type directly, call its Dispose method in a try/catch block. To dispose of it indirectly, use a language construct such as using (in C#) or Using (in Visual Basic). For more information, see the "Using an Object that Implements IDisposable" section in the IDisposable interface topic.

Wichteg

Isolated storage is not available for Windows 8.x Store apps. Instead, use the application data classes in the Windows.Storage namespaces included in the Windows Runtime API to store local data and files. For more information, see Application data in the Windows Dev Center.

Constructors

IsolatedStorageFileStream(String, FileMode, FileAccess, FileShare, Int32, IsolatedStorageFile)	Initializes a new instance of the IsolatedStorageFileStream class giving access to the file designated by path, in the specified mode, with the specified file access, using the file sharing mode specified by share, with the bufferSize specified, and in the context of the IsolatedStorageFile specified by isf.
IsolatedStorageFileStream(String, FileMode, FileAccess, FileShare, Int32)	Initializes a new instance of the IsolatedStorageFileStream class giving access to the file designated by path, in the specified mode, with the specified file access, using the file sharing mode specified by share, with the bufferSize specified.
IsolatedStorageFileStream(String, FileMode, FileAccess, FileShare, IsolatedStorageFile)	Initializes a new instance of the IsolatedStorageFileStream class giving access to the file designated by path, in the specified mode, with the specified file access, using the file sharing mode specified by share, and in the context of the IsolatedStorageFile specified by isf.
IsolatedStorageFileStream(String, FileMode, FileAccess, FileShare)	Initializes a new instance of the IsolatedStorageFileStream class giving access to the file designated by path, in the specified mode, with the specified file access, using the file sharing mode specified by share.
IsolatedStorageFileStream(String, FileMode, FileAccess, IsolatedStorageFile)	Initializes a new instance of the IsolatedStorageFileStream class giving access to the file designated by path in the specified mode, with the specified file access, and in the context of the IsolatedStorageFile specified by isf.
IsolatedStorageFileStream(String, FileMode, FileAccess)	Initializes a new instance of the IsolatedStorageFileStream class giving access to the file designated by path, in the specified mode, with the kind of access requested.
IsolatedStorageFileStream(String, FileMode, IsolatedStorageFile)	Initializes a new instance of the IsolatedStorageFileStream class giving access to the file designated by path, in the specified mode, and in the context of the IsolatedStorageFile specified by isf.
IsolatedStorageFileStream(String, FileMode)	Initializes a new instance of an IsolatedStorageFileStream object giving access to the file designated by path in the specified mode.

Properties

CanRead	Gets a Boolean value indicating whether the file can be read.
CanSeek	Gets a Boolean value indicating whether seek operations are supported.
CanTimeout	Gets a value that determines whether the current stream can time out. (Inherited from Stream)
CanWrite	Gets a Boolean value indicating whether you can write to the file.
Handle	Obsolete. Gets the file handle for the file that the current IsolatedStorageFileStream object encapsulates. Accessing this property is not permitted on an IsolatedStorageFileStream object, and throws an IsolatedStorageException.
IsAsync	Gets a Boolean value indicating whether the IsolatedStorageFileStream object was opened asynchronously or synchronously.
Length	Gets the length of the IsolatedStorageFileStream object.
Name	Gets the absolute path of the file opened in the FileStream. (Inherited from FileStream)
Position	Gets or sets the current position of the current IsolatedStorageFileStream object.
ReadTimeout	Gets or sets a value, in milliseconds, that determines how long the stream will attempt to read before timing out. (Inherited from Stream)
SafeFileHandle	Gets a SafeFileHandle object that represents the operating system file handle for the file that the current IsolatedStorageFileStream object encapsulates.
WriteTimeout	Gets or sets a value, in milliseconds, that determines how long the stream will attempt to write before timing out. (Inherited from Stream)

Methods

BeginRead(Byte[], Int32, Int32, AsyncCallback, Object)	Begins an asynchronous read.
BeginWrite(Byte[], Int32, Int32, AsyncCallback, Object)	Begins an asynchronous write.
CopyTo(Stream, Int32)	Reads the bytes from the current stream and writes them to another stream, using a specified buffer size. Both streams positions are advanced by the number of bytes copied. (Inherited from FileStream)
CopyTo(Stream)	Reads the bytes from the current stream and writes them to another stream. Both streams positions are advanced by the number of bytes copied. (Inherited from Stream)
CopyToAsync(Stream, CancellationToken)	Asynchronously reads the bytes from the current stream and writes them to another stream, using a specified cancellation token. Both streams positions are advanced by the number of bytes copied. (Inherited from Stream)
CopyToAsync(Stream, Int32, CancellationToken)	Asynchronously reads the bytes from the current file stream and writes them to another stream, using a specified buffer size and cancellation token. (Inherited from FileStream)
CopyToAsync(Stream, Int32)	Asynchronously reads the bytes from the current stream and writes them to another stream, using a specified buffer size. Both streams positions are advanced by the number of bytes copied. (Inherited from Stream)
CopyToAsync(Stream)	Asynchronously reads the bytes from the current stream and writes them to another stream. Both streams positions are advanced by the number of bytes copied. (Inherited from Stream)
CreateWaitHandle()	Obsolete. Allocates a WaitHandle object. (Inherited from Stream)
Dispose()	Releases all resources used by the Stream. (Inherited from Stream)
Dispose(Boolean)	Releases the unmanaged resources used by the IsolatedStorageFileStream and optionally releases the managed resources.
DisposeAsync()	Asynchronously releases the unmanaged resources used by the IsolatedStorageFileStream.
EndRead(IAsyncResult)	Ends a pending asynchronous read request.
EndWrite(IAsyncResult)	Ends an asynchronous write.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
Flush()	Clears buffers for this stream and causes any buffered data to be written to the file.
Flush(Boolean)	Clears buffers for this stream and causes any buffered data to be written to the file, and also clears all intermediate file buffers.
FlushAsync()	Asynchronously clears all buffers for this stream and causes any buffered data to be written to the underlying device. (Inherited from Stream)
FlushAsync(CancellationToken)	Asynchronously clears buffers for this stream and causes any buffered data to be written to the file.
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetLifetimeService()	Obsolete. Retrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject)
GetType()	Gets the Type of the current instance. (Inherited from Object)
InitializeLifetimeService()	Obsolete. Obtains a lifetime service object to control the lifetime policy for this instance. (Inherited from MarshalByRefObject)
Lock(Int64, Int64)	Prevents other processes from reading from or writing to the stream.
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
MemberwiseClone(Boolean)	Creates a shallow copy of the current MarshalByRefObject object. (Inherited from MarshalByRefObject)
ObjectInvariant()	Obsolete. Provides support for a Contract. (Inherited from Stream)
Read(Byte[], Int32, Int32)	Copies bytes from the current buffered IsolatedStorageFileStream object to a byte array.
Read(Span<Byte>)	Copies bytes from the current buffered IsolatedStorageFileStream object to a byte span.
ReadAsync(Byte[], Int32, Int32, CancellationToken)	Asynchronously copies bytes from the current buffered IsolatedStorageFileStream object to a byte array.
ReadAsync(Byte[], Int32, Int32)	Asynchronously reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read. (Inherited from Stream)
ReadAsync(Memory<Byte>, CancellationToken)	Asynchronously copies bytes from the current buffered IsolatedStorageFileStream object to a byte memory range.
ReadAtLeast(Span<Byte>, Int32, Boolean)	Reads at least a minimum number of bytes from the current stream and advances the position within the stream by the number of bytes read. (Inherited from Stream)
ReadAtLeastAsync(Memory<Byte>, Int32, Boolean, CancellationToken)	Asynchronously reads at least a minimum number of bytes from the current stream, advances the position within the stream by the number of bytes read, and monitors cancellation requests. (Inherited from Stream)
ReadByte()	Reads a single byte from the IsolatedStorageFileStream object in isolated storage.
ReadExactly(Byte[], Int32, Int32)	Reads count number of bytes from the current stream and advances the position within the stream. (Inherited from Stream)
ReadExactly(Span<Byte>)	Reads bytes from the current stream and advances the position within the stream until the buffer is filled. (Inherited from Stream)
ReadExactlyAsync(Byte[], Int32, Int32, CancellationToken)	Asynchronously reads count number of bytes from the current stream, advances the position within the stream, and monitors cancellation requests. (Inherited from Stream)
ReadExactlyAsync(Memory<Byte>, CancellationToken)	Asynchronously reads bytes from the current stream, advances the position within the stream until the buffer is filled, and monitors cancellation requests. (Inherited from Stream)
Seek(Int64, SeekOrigin)	Sets the current position of this IsolatedStorageFileStream object to the specified value.
SetLength(Int64)	Sets the length of this IsolatedStorageFileStream object to the specified value.
ToString()	Returns a string that represents the current object. (Inherited from Object)
Unlock(Int64, Int64)	Allows other processes to access all or part of a file that was previously locked.
Write(Byte[], Int32, Int32)	Writes a block of bytes to the isolated storage file stream object using data read from a buffer consisting of a byte array.
Write(ReadOnlySpan<Byte>)	Writes a block of bytes to the isolated storage file stream object using data read from a buffer consisting of a read-only byte span.
WriteAsync(Byte[], Int32, Int32, CancellationToken)	Asynchronously writes a block of bytes to the isolated storage file stream object using data read from a buffer consisting of a byte array.
WriteAsync(Byte[], Int32, Int32)	Asynchronously writes a sequence of bytes to the current stream and advances the current position within this stream by the number of bytes written. (Inherited from Stream)
WriteAsync(ReadOnlyMemory<Byte>, CancellationToken)	Asynchronously writes a block of bytes to the isolated storage file stream object using data read from a buffer consisting of a read-only byte memory range.
WriteByte(Byte)	Writes a single byte to the IsolatedStorageFileStream object.

Extension Methods

GetAccessControl(FileStream)	Returns the security information of a file.
SetAccessControl(FileStream, FileSecurity)	Changes the security attributes of an existing file.
CopyToAsync(Stream, PipeWriter, CancellationToken)	Asynchronously reads the bytes from the Stream and writes them to the specified PipeWriter, using a cancellation token.
ConfigureAwait(IAsyncDisposable, Boolean)	Configures how awaits on the tasks returned from an async disposable will be performed.

Applies to