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IsolatedStorageFileStream Class

Exposes a file within isolated storage.

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

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

'Declaration
<ComVisibleAttribute(True)> _
Public Class IsolatedStorageFileStream _
	Inherits FileStream

The IsolatedStorageFileStream type exposes the following members.

  NameDescription
Public methodIsolatedStorageFileStream(String, FileMode)Initializes a new instance of an IsolatedStorageFileStream object giving access to the file designated by path in the specified mode.
Public methodIsolatedStorageFileStream(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.
Public methodIsolatedStorageFileStream(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.
Public methodIsolatedStorageFileStream(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.
Public methodIsolatedStorageFileStream(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.
Public methodIsolatedStorageFileStream(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.
Public methodIsolatedStorageFileStream(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.
Public methodIsolatedStorageFileStream(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.
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  NameDescription
Public propertyCanReadGets a Boolean value indicating whether the file can be read. (Overrides FileStream.CanRead.)
Public propertyCanSeekGets a Boolean value indicating whether seek operations are supported. (Overrides FileStream.CanSeek.)
Public propertyCanTimeoutGets a value that determines whether the current stream can time out. (Inherited from Stream.)
Public propertyCanWriteGets a Boolean value indicating whether you can write to the file. (Overrides FileStream.CanWrite.)
Public propertyHandle 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. (Overrides FileStream.Handle.)
Public propertyIsAsyncGets a Boolean value indicating whether the IsolatedStorageFileStream object was opened asynchronously or synchronously. (Overrides FileStream.IsAsync.)
Public propertyLengthGets the length of the IsolatedStorageFileStream object. (Overrides FileStream.Length.)
Public propertyNameGets the name of the FileStream that was passed to the constructor. (Inherited from FileStream.)
Public propertyPositionGets or sets the current position of the current IsolatedStorageFileStream object. (Overrides FileStream.Position.)
Public propertyReadTimeoutGets or sets a value, in miliseconds, that determines how long the stream will attempt to read before timing out. (Inherited from Stream.)
Public propertySafeFileHandleGets a SafeFileHandle object that represents the operating system file handle for the file that the current IsolatedStorageFileStream object encapsulates. (Overrides FileStream.SafeFileHandle.)
Public propertyWriteTimeoutGets or sets a value, in miliseconds, that determines how long the stream will attempt to write before timing out. (Inherited from Stream.)
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  NameDescription
Public methodBeginReadBegins an asynchronous read. (Overrides FileStream.BeginRead(Byte(), Int32, Int32, AsyncCallback, Object).)
Public methodBeginWriteBegins an asynchronous write. (Overrides FileStream.BeginWrite(Byte(), Int32, Int32, AsyncCallback, Object).)
Public methodCloseCloses the current stream and releases any resources (such as sockets and file handles) associated with the current stream. (Inherited from Stream.)
Public methodCopyTo(Stream)Reads the bytes from the current stream and writes them to the destination stream. (Inherited from Stream.)
Public methodCopyTo(Stream, Int32)Reads all the bytes from the current stream and writes them to a destination stream, using a specified buffer size. (Inherited from Stream.)
Public methodCreateObjRefCreates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from MarshalByRefObject.)
Protected methodCreateWaitHandle Obsolete. Allocates a WaitHandle object. (Inherited from Stream.)
Public methodDisposeReleases all resources used by the Stream. (Inherited from Stream.)
Protected methodDispose(Boolean)Releases the unmanaged resources used by the IsolatedStorageFileStream and optionally releases the managed resources. (Overrides FileStream.Dispose(Boolean).)
Public methodEndReadEnds a pending asynchronous read request. (Overrides FileStream.EndRead(IAsyncResult).)
Public methodEndWriteEnds an asynchronous write. (Overrides FileStream.EndWrite(IAsyncResult).)
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeEnsures that resources are freed and other cleanup operations are performed when the garbage collector reclaims the FileStream. (Inherited from FileStream.)
Public methodFlushClears buffers for this stream and causes any buffered data to be written to the file. (Overrides FileStream.Flush.)
Public methodFlush(Boolean)Clears buffers for this stream and causes any buffered data to be written to the file, and also clears all intermediate file buffers. (Overrides FileStream.Flush(Boolean).)
Public methodGetAccessControlGets a FileSecurity object that encapsulates the access control list (ACL) entries for the file described by the current FileStream object. (Inherited from FileStream.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetLifetimeServiceRetrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodInitializeLifetimeServiceObtains a lifetime service object to control the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Public methodLockPrevents other processes from reading from or writing to the FileStream. (Inherited from FileStream.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected methodMemberwiseClone(Boolean)Creates a shallow copy of the current MarshalByRefObject object. (Inherited from MarshalByRefObject.)
Protected methodObjectInvariantInfrastructure. Provides support for a Contract. (Inherited from Stream.)
Public methodReadCopies bytes from the current buffered IsolatedStorageFileStream object to an array. (Overrides FileStream.Read(Byte(), Int32, Int32).)
Public methodReadByteReads a single byte from the IsolatedStorageFileStream object in isolated storage. (Overrides FileStream.ReadByte.)
Public methodSeekSets the current position of this IsolatedStorageFileStream object to the specified value. (Overrides FileStream.Seek(Int64, SeekOrigin).)
Public methodSetAccessControlApplies access control list (ACL) entries described by a FileSecurity object to the file described by the current FileStream object. (Inherited from FileStream.)
Public methodSetLengthSets the length of this IsolatedStorageFileStream object to the specified value. (Overrides FileStream.SetLength(Int64).)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodUnlockAllows access by other processes to all or part of a file that was previously locked. (Inherited from FileStream.)
Public methodWriteWrites a block of bytes to the IsolatedStorageFileStream object using data read from a byte array. (Overrides FileStream.Write(Byte(), Int32, Int32).)
Public methodWriteByteWrites a single byte to the IsolatedStorageFileStream object. (Overrides FileStream.WriteByte(Byte).)
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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 Storeadm.exe (Isolated Storage Tool) 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.
Imports System
Imports System.IO
Imports System.IO.IsolatedStorage
Imports System.Security.Policy
Imports Microsoft.VisualBasic
Imports Microsoft.Win32.SafeHandles
Imports System.Security.Permissions



Namespace ISOCS
    _
    Class ConsoleApp


        <STAThread()> _
       Overloads Shared Sub Main(ByVal args() As String)

            ' Prompt the user for their username.
            Console.WriteLine("Enter your login ID:")

            ' Does no error checking.
            Dim lp As New LoginPrefs(Console.ReadLine())

            If lp.NewPrefs Then
                Console.WriteLine("Please set preferences for a new user.")
                GatherInfoFromUser(lp)

                ' Write the new preferences to storage.
                Dim percentUsed As Double = 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}" & ControlChars.Cr & " and your sports site has been set to {1}.", lp.NewsUrl, lp.SportsUrl)
            End If
            lp.GetIsoStoreInfo()
            Console.WriteLine("Enter 'd' to delete the IsolatedStorage files and exit, or press any other key to exit without deleting files.")
            Dim consoleInput As String = Console.ReadLine()
            If consoleInput.ToLower() = "d" Then
                lp.DeleteFiles()
                lp.DeleteDirectories()
            End If
        End Sub 'Main


        Shared Sub GatherInfoFromUser(ByVal lp As LoginPrefs)
            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()
        End Sub 'GatherInfoFromUser
    End Class 'ConsoleApp
    _

    <SecurityPermissionAttribute(SecurityAction.Demand, Flags:=SecurityPermissionFlag.UnmanagedCode)> _
    Public Class LoginPrefs

        Public Sub New(ByVal myUserName As String)
            userName = myUserName
            myNewPrefs = GetPrefsForUser()
        End Sub 'New
        Private userName As String

        Private myNewsUrl As String

        Public Property NewsUrl() As String
            Get
                Return myNewsUrl
            End Get
            Set(ByVal Value As String)
                myNewsUrl = Value
            End Set
        End Property
        Private mySportsUrl As String

        Public Property SportsUrl() As String
            Get
                Return mySportsUrl
            End Get
            Set(ByVal Value As String)
                mySportsUrl = Value
            End Set
        End Property
        Private myNewPrefs As Boolean

        Public ReadOnly Property NewPrefs() As Boolean
            Get
                Return myNewPrefs
            End Get
        End Property

        Private Function GetPrefsForUser() As Boolean
            Try
                ' Retrieve an IsolatedStorageFile for the current Domain and Assembly.
                Dim isoFile As IsolatedStorageFile = _
                    IsolatedStorageFile.GetStore(IsolatedStorageScope.User _
                    Or IsolatedStorageScope.Assembly _
                    Or IsolatedStorageScope.Domain, Nothing, Nothing)

                Dim isoStream As New IsolatedStorageFileStream(Me.userName, FileMode.Open, _
                    FileAccess.Read, FileShare.Read)
                ' farThe 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

                    Dim aFileHandle As SafeFileHandle = isoStream.SafeFileHandle
                    Console.WriteLine(("A pointer to a file handle has been obtained. " & aFileHandle.ToString() & " " & aFileHandle.GetHashCode()))

                Catch ex As Exception
                    ' Handle the exception.
                    Console.WriteLine("Expected exception")
                    Console.WriteLine(ex.ToString())
                End Try

                Dim reader As New StreamReader(isoStream)
                ' Read the data.
                Me.NewsUrl = reader.ReadLine()
                Me.SportsUrl = reader.ReadLine()
                reader.Close()
                isoFile.Close()
                Return False
            Catch ex As System.IO.FileNotFoundException
                ' Expected exception if a file cannot be found. This indicates that we have a new user.
                Return True
            End Try
        End Function 'GetPrefsForUser

        Public Function GetIsoStoreInfo() As Boolean
            Try
                'Get a User store with type evidence for the current Domain and the Assembly.
                Dim isoFile As IsolatedStorageFile = _
                    IsolatedStorageFile.GetStore(IsolatedStorageScope.User Or _
                    IsolatedStorageScope.Assembly Or IsolatedStorageScope.Domain, _
                    GetType(System.Security.Policy.Url), GetType(System.Security.Policy.Url))
                Dim dirNames As String() = isoFile.GetDirectoryNames("*")
                Dim fileNames As String() = isoFile.GetFileNames("*")
                Dim name As String

                ' List directories currently in this Isolated Storage.
                If dirNames.Length > 0 Then

                    For Each name In dirNames
                        Console.WriteLine("Directory Name: " & name)
                    Next name
                End If

                ' 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 Then

                    For Each name In fileNames
                        Console.WriteLine("File Name: " & name)
                    Next name
                End If
                isoFile.Close()
                Return True
            Catch ex As Exception
                Console.WriteLine(ex.ToString())
            End Try
        End Function 'GetIsoStoreInfo

        Public Function SetPrefsForUser() As Double
            Try
                Dim isoFile As IsolatedStorageFile
                isoFile = IsolatedStorageFile.GetUserStoreForDomain()

                ' Open or create a writable file.
                Dim isoStream As New IsolatedStorageFileStream(Me.userName, FileMode.OpenOrCreate, _
                    FileAccess.Write, isoFile)

                Dim writer As New StreamWriter(isoStream)
                writer.WriteLine(Me.NewsUrl)
                writer.WriteLine(Me.SportsUrl)
                ' Calculate the amount of space used to record the user's preferences.
                Dim d As Double = Convert.ToDouble(isoFile.CurrentSize) / Convert.ToDouble(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 ex As Exception
                ' Add code here to handle the exception.
                Console.WriteLine(ex)
                Return 0.0
            End Try
        End Function 'SetPrefsForUser


        Public Sub DeleteFiles()
            Try
                Dim isoFile As IsolatedStorageFile = IsolatedStorageFile.GetStore(IsolatedStorageScope.User Or IsolatedStorageScope.Assembly Or IsolatedStorageScope.Domain, GetType(System.Security.Policy.Url), GetType(System.Security.Policy.Url))
                Dim name As String
                Dim dirNames As String() = isoFile.GetDirectoryNames("*")
                Dim fileNames As String() = 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 Then
                    For Each name In fileNames
                        ' Delete the files.
                        isoFile.DeleteFile(name)
                    Next name
                    'Confirm no files are left.
                    fileNames = isoFile.GetFileNames("*")
                End If
            Catch ex As Exception
                Console.WriteLine(ex.ToString())
            End Try
        End Sub 'DeleteFiles

        ' 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 Sub DeleteDirectories()
            Try
                Dim isoFile As IsolatedStorageFile = IsolatedStorageFile.GetStore(IsolatedStorageScope.User _
                    Or IsolatedStorageScope.Assembly Or IsolatedStorageScope.Domain, _
                    GetType(System.Security.Policy.Url), GetType(System.Security.Policy.Url))
                Dim name As String
                Dim dirNames As String() = isoFile.GetDirectoryNames("*")
                Dim fileNames As String() = isoFile.GetFileNames("Archive\*")
                ' Delete all the files currently in the Archive directory.
                If fileNames.Length > 0 Then
                    For Each name In fileNames
                        isoFile.DeleteFile(("Archive\" & name))
                    Next name
                    'Confirm no files are left.
                    fileNames = isoFile.GetFileNames("Archive\*")
                End If
                If dirNames.Length > 0 Then
                    For Each name In dirNames
                        ' Delete the Archive directory.
                        isoFile.DeleteDirectory(name)
                    Next name
                End If
                dirNames = isoFile.GetDirectoryNames("*")
                isoFile.Remove()
            Catch ex As Exception
                Console.WriteLine(ex.ToString())
            End Try
        End Sub 'DeleteDirectories

        Public Function SetNewPrefsForUser() As Double
            Try
                Dim inputChar As Byte
                Dim isoFile As IsolatedStorageFile = IsolatedStorageFile.GetStore(IsolatedStorageScope.User Or IsolatedStorageScope.Assembly Or IsolatedStorageScope.Domain, GetType(System.Security.Policy.Url), GetType(System.Security.Policy.Url))

                ' If this is not a new user, archive the old preferences and 
                ' overwrite them using the new preferences.
                If Not Me.myNewPrefs Then
                    If isoFile.GetDirectoryNames("Archive").Length = 0 Then
                        isoFile.CreateDirectory("Archive")
                    Else

                        Dim source As New IsolatedStorageFileStream(Me.userName, FileMode.OpenOrCreate, isoFile)
                        Dim canWrite, canRead As Boolean
                        ' This is the stream from which data will be read.
                        If source.CanRead Then canRead = True Else canRead = False
                        Console.WriteLine("Is the source file readable? " & canRead)
                        Console.WriteLine("Creating new IsolatedStorageFileStream for Archive.")
                        ' Open or create a writable file.
                        Dim target As New IsolatedStorageFileStream("Archive\ " & Me.userName, _
                             FileMode.OpenOrCreate, FileAccess.Write, FileShare.Write, isoFile)
                        ' This is the stream to which data will be written.
                        If target.CanWrite Then canWrite = True Else canWrite = False
                        Console.WriteLine("Is the target file writable? " & canWrite)
                        target.SetLength(0)  'rewind the target file

                        ' Stream the old file to a new file in the Archive directory.
                        If source.IsAsync And target.IsAsync Then
                            ' 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 = CByte(source.ReadByte())
                                target.WriteByte(inputChar)
                            End While

                            ' Determine the size of the IsolatedStorageFileStream
                            ' by checking its Length property.
                            Console.WriteLine(("Total Bytes Read: " & source.Length))
                        End If

                        ' After you have read and written to the streams, close them.	
                        target.Close()
                        source.Close()
                    End If
                End If
                ' Open or create a writable file with a maximum size of 10K.
                Dim isoStream As New IsolatedStorageFileStream(Me.userName, FileMode.OpenOrCreate, _
                    FileAccess.Write, FileShare.Write, 10240, isoFile)
                isoStream.SetLength(0) 'Position to overwrite the old data.
                Dim writer As New StreamWriter(isoStream)
                ' Update the data based on the new inputs.
                writer.WriteLine(Me.NewsUrl)
                writer.WriteLine(Me.SportsUrl)

                '  Calculate the amount of space used to record this user's preferences.
                Dim d As Double = Convert.ToDouble(isoFile.CurrentSize) / Convert.ToDouble(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 ex As Exception
                Console.WriteLine(ex.ToString())
                Return 0.0
            End Try
        End Function 'SetNewPrefsForUser
    End Class 'LoginPrefs
End Namespace 'ISOCS


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

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

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