IsolatedStorageFile Class
This page is specific to:Microsoft Version:1.12.03.03.5Silverlight 34.0
.NET Framework Class Library for Silverlight
IsolatedStorageFile Class

Represents an isolated storage area containing files and directories.

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

'Usage

Dim instance As IsolatedStorageFile

'Declaration

Public NotInheritable Class IsolatedStorageFile _
    Implements IDisposable
Remarks

This class abstracts the virtual file system for isolated storage. An IsolatedStorageFile object corresponds to a specific isolated storage scope, where files represented by IsolatedStorageFileStream objects exist. Applications can use isolated storage to save data in their own isolated portion of the file system, without having to specify a particular path within the file system.

The root of the virtual file system is located in a per-user, obfuscated folder on the physical file system. Each unique identifier provided by the host maps to a different root, which gives each application its own virtual file system. An application cannot navigate out of its own file system into another.

Since isolated stores are scoped to particular assemblies, most other managed code will not be able to access your code's data (highly trusted managed code and administration tools can access stores from other assemblies). Unmanaged code can access any isolated stores.

Examples

The following example shows how to use an IsolatedStorageFile object for most I/O tasks.

Imports System
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Input
Imports System.IO
Imports System.IO.IsolatedStorage
Imports System.Collections
Imports System.Text


Class Example

    Public Shared Sub Demo(ByVal outputBlock As TextBlock)
        ' Obtain an isolated store for an application.
        Try
            Using store As IsolatedStorageFile = _
                IsolatedStorageFile.GetUserStoreForApplication()
                ' Use a StringBuilder to construct output.
                Dim sb As StringBuilder = New StringBuilder

                ' Create three directories in the root.
                store.CreateDirectory("MyApp1")
                store.CreateDirectory("MyApp2")
                store.CreateDirectory("MyApp3")

                ' Create three subdirectories under MyApp1.
                Dim subdirectory1 As String = Path.Combine("MyApp1", "SubDir1")
                Dim subdirectory2 As String = Path.Combine("MyApp1", "SubDir2")
                Dim subdirectory3 As String = Path.Combine("MyApp1", "SubDir3")
                store.CreateDirectory(subdirectory1)
                store.CreateDirectory(subdirectory2)
                store.CreateDirectory(subdirectory3)

                ' Create a file in the root.
                Dim rootFile As IsolatedStorageFileStream = _
                    store.CreateFile("InTheRoot.txt")
                rootFile.Close()


                ' Create a file in a subdirectory.
                Dim subDirFile As IsolatedStorageFileStream = _
                    store.CreateFile(Path.Combine(subdirectory1, "MyApp1A.txt"))
                subDirFile.Close()

                ' Gather file information.
                Dim directoriesInTheRoot() As String = store.GetDirectoryNames

                Dim filesInTheRoot() As String = store.GetFileNames

                Dim searchpath As String = Path.Combine(subdirectory1, "*.*")
                Dim filesInSubDirs() As String = store.GetFileNames(searchpath)

                ' Find subdirectories within the MyApp1
                ' directory using the multi character '*' wildcard.
                Dim subDirectories() As String = _
                    store.GetDirectoryNames(Path.Combine("MyApp1", "*"))

                ' List file infomration

                ' List the directories in the root.
                sb.AppendLine("Directories in root:")
                For Each dir As String In directoriesInTheRoot
                    sb.AppendLine((" - " + dir))
                Next
                sb.AppendLine()
                ' List the subdirectories under MyApp1.
                sb.AppendLine("Directories under MyApp1:")
                For Each sDir As String In subDirectories
                    sb.AppendLine((" - " + sDir))
                Next
                sb.AppendLine()
                ' List files in the root.
                sb.AppendLine("Files in the root:")
                For Each fileName As String In filesInTheRoot
                    sb.AppendLine((" - " + fileName))
                Next
                sb.AppendLine()
                ' List files in MyApp1\SubDir1.
                sb.AppendLine("Files in MyApp1\SubDir1:")
                For Each fileName As String In filesInSubDirs
                    sb.AppendLine((" - " + fileName))
                Next
                sb.AppendLine()

                ' Write to an existing file: MyApp1\SubDir1\MyApp1A.txt

                ' Determine if the file exists before writing to it.
                Dim filePath As String = Path.Combine(subdirectory1, "MyApp1A.txt")

                If store.FileExists(filePath) Then
                    Try
                        Using sw As StreamWriter = _
                            New StreamWriter(store.OpenFile(filePath, FileMode.Open, FileAccess.Write))

                            sw.WriteLine("To do list:")
                            sw.WriteLine("1. Buy supplies.")
                        End Using

                    Catch ex As IsolatedStorageException
                        sb.AppendLine(ex.Message)
                    End Try
                Else
                    sb.AppendLine((filePath + "does not exist"))
                End If

                ' Read the contents of the file: MyApp1\SubDir1\MyApp1A.txt
                Try
                    Using reader As StreamReader = _
                        New StreamReader(store.OpenFile(filePath, FileMode.Open, FileAccess.Read))
                        Dim contents As String = reader.ReadToEnd
                        sb.AppendLine(filePath + " contents:")
                        sb.AppendLine(contents)
                    End Using
                Catch ex As IsolatedStorageException
                    sb.Append(ex.Message)
                End Try


                ' Delete a file.
                Try
                    If store.FileExists(filePath) Then
                        store.DeleteFile(filePath)
                    End If
                Catch ex As IsolatedStorageException
                    sb.AppendLine(ex.Message)
                End Try

                ' Delete a specific directory.
                Dim dirDelete As String = Path.Combine("MyApp1", "SubDir3")
                Try
                    If store.DirectoryExists(dirDelete) Then
                        store.DeleteDirectory(dirDelete)
                    End If
                Catch ex As IsolatedStorageException
                    sb.AppendLine(ex.Message)
                End Try

                sb.AppendLine()
                ' remove the store
                store.Remove()

                sb.AppendLine("Store removed.")
                outputBlock.Text = sb.ToString()
            End Using
        Catch Ex As IsolatedStorageException
            ' TODO: Handle that store was unable to be accessed.
        End Try
    End Sub
End Class

' Quota status in increase examples
Class StoreQuota

    ' Assumes an event handler for the MouseLeftbuttonUp
    ' event is defined for a control named 'IncreaseQuota'
    ' In the control's XAML: MouseLeftButtonUp="IncreaseQuota_OnLeftMouseButtonUp"
    Public Sub IncreaseQuota_OnClick(ByVal sender As Object, ByVal e As MouseEventArgs)
        ' Obtain an isolated store for an application.
        Try
            Using store As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForApplication()
                ' Request 5MB more space in bytes.
                Dim spaceToAdd As Int64 = 5242880
                Dim curAvail As Int64 = store.AvailableFreeSpace
                ' If available space is less than
                ' what is requested, try to increase.
                If (curAvail < spaceToAdd) Then
                    ' Request more quota space.
                    If Not store.IncreaseQuotaTo((store.Quota + spaceToAdd)) Then
                        ' The user clicked NO to the
                        ' host's prompt to approve the quota increase.
                    Else
                        ' The user clicked YES to the
                        ' host's prompt to approve the quota increase.
                    End If
                End If
            End Using
        Catch Ex As IsolatedStorageException

            ' TODO: Handle that store could not be accessed.
        End Try
    End Sub




    Public Shared Sub ShowIsoStoreStatus(ByVal inputBlock As TextBlock)
        ' Obtain an isolated store for an application.
        Try
            Using store As IsolatedStorageFile = _
              IsolatedStorageFile.GetUserStoreForApplication()
                Dim spaceUsed As String = (store.Quota - store.AvailableFreeSpace).ToString
                Dim spaceAvailable As String = store.AvailableFreeSpace.ToString
                Dim curQuota As String = store.Quota.ToString
                inputBlock.Text = String.Format("Quota: {0} bytes, Used: {1} bytes, Available: {2} bytes", _
                                         curQuota, spaceUsed, spaceAvailable)
            End Using
        Catch Ex As IsolatedStorageException
            inputBlock.Text = "Unable to access store."
        End Try
    End Sub
End Class

' This example's Example.Demo method 
' produces the following output:
' -----
' Directories in root:
' - MyApp1
' - MyApp2
' - MyApp3

' Directories under MyApp1:
' - SubDir1
' - SubDir2
' - SubDir3

' Files in the root:
' - InTheRoot.txt

' Files in MyApp1\SubDir1:
' - MyApp1A.txt

' MyApp1\SubDir1\MyApp1A.txt contents:
' To do list:
' 1. Buy supplies.

' Store removed.
' -----



Inheritance Hierarchy

System..::.Object
  System.IO.IsolatedStorage..::.IsolatedStorageFile
Thread Safety

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

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

See Also

Reference

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