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IsolatedStorageFileStream Class

Exposes a file within isolated storage.

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

[ComVisibleAttribute(true)]
public ref class IsolatedStorageFileStream : public 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 namespace System;
using namespace System::IO;
using namespace System::IO::IsolatedStorage;
using namespace System::Security::Policy;
using namespace System::Security::Permissions;

public ref class LoginPrefs
{
private:
   String^ userName;
   String^ newsUrl;
   String^ sportsUrl;
   bool newPrefs;

public:

   [SecurityPermissionAttribute(SecurityAction::Demand, Flags=SecurityPermissionFlag::UnmanagedCode)]
   bool GetPrefsForUser()
   {
      try
      {

         // Retrieve an IsolatedStorageFile for the current Domain and Assembly.
         IsolatedStorageFile^ isoFile = IsolatedStorageFile::GetStore( static_cast<IsolatedStorageScope>(IsolatedStorageScope::User | IsolatedStorageScope::Assembly | IsolatedStorageScope::Domain), (Type^)nullptr, nullptr );
         IsolatedStorageFileStream^ isoStream = gcnew IsolatedStorageFileStream( this->userName,FileMode::Open,FileAccess::ReadWrite,isoFile );

         // 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
         {
            IntPtr aFileHandle = isoStream->Handle;
            Console::WriteLine( "A pointer to a file handle has been obtained. {0} {1}", aFileHandle, aFileHandle.GetHashCode() );
         }
         catch ( Exception^ e ) 
         {

            // Handle the exception.
            Console::WriteLine( "Expected exception" );
            Console::WriteLine( e->ToString() );
         }

         StreamReader^ reader = gcnew StreamReader( isoStream );

         // Read the data. 
         this->NewsUrl = reader->ReadLine();
         this->SportsUrl = reader->ReadLine();
         reader->Close();
         isoFile->Close();
         isoStream->Close();
         return false;
      }
      catch ( Exception^ e ) 
      {

         // Expected exception if a file cannot be found. This indicates that we have a new user.
         String^ errorMessage = e->ToString();
         return true;
      }

   }


   bool GetIsoStoreInfo()
   {

      // Get a User store with type evidence for the current Domain and the Assembly.
      IsolatedStorageFile^ isoFile = IsolatedStorageFile::GetStore( static_cast<IsolatedStorageScope>(IsolatedStorageScope::User | IsolatedStorageScope::Assembly | IsolatedStorageScope::Domain), System::Security::Policy::Url::typeid, System::Security::Policy::Url::typeid );

      array<String^>^dirNames = isoFile->GetDirectoryNames( "*" );
      array<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: {0}", 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: {0}", fileNames[ i ] );

         }
      }


      isoFile->Close();
      return true;
   }


   double SetPrefsForUser()
   {
      try
      {

         IsolatedStorageFile^ isoFile;
         isoFile = IsolatedStorageFile::GetUserStoreForDomain();

         // Open or create a writable file.
         IsolatedStorageFileStream^ isoStream = gcnew IsolatedStorageFileStream( this->userName,FileMode::OpenOrCreate,FileAccess::Write,isoFile );
         StreamWriter^ writer = gcnew 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 = {0}", isoFile->CurrentSize.ToString() );
         Console::WriteLine( "MaximumSize = {0}", isoFile->MaximumSize.ToString() );
         writer->Close();
         isoFile->Close();
         isoStream->Close();
         return d;

      }
      catch ( Exception^ e ) 
      {      
         // Add code here to handle the exception.
         Console::WriteLine( e->ToString() );
         return 0.0;
      }

   }


   void DeleteFiles()
   {

      try
      {
         IsolatedStorageFile^ isoFile = IsolatedStorageFile::GetStore( static_cast<IsolatedStorageScope>(IsolatedStorageScope::User | IsolatedStorageScope::Assembly | IsolatedStorageScope::Domain), System::Security::Policy::Url::typeid, System::Security::Policy::Url::typeid );
         array<String^>^dirNames = isoFile->GetDirectoryNames( "*" );
         array<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 ] );

            }
            fileNames = isoFile->GetFileNames( "*" );
         }
         isoFile->Close();
      }
      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. 
   void DeleteDirectories()
   {
      try
      {
         IsolatedStorageFile^ isoFile = IsolatedStorageFile::GetStore( static_cast<IsolatedStorageScope>(IsolatedStorageScope::User | IsolatedStorageScope::Assembly | IsolatedStorageScope::Domain), System::Security::Policy::Url::typeid, System::Security::Policy::Url::typeid );
         array<String^>^dirNames = isoFile->GetDirectoryNames( "*" );
         array<String^>^fileNames = isoFile->GetFileNames( "Archive\\*" );

         // Delete the current files within the Archive directory. 
         if ( fileNames->Length > 0 )
         {
            for ( int i = 0; i < fileNames->Length; ++i )
            {

               //delete files
               isoFile->DeleteFile( String::Concat("Archive\\", fileNames[ i ]) );

            }
            fileNames = isoFile->GetFileNames( "Archive\\*" );
         }
         if ( dirNames->Length > 0 )
         {
            for ( int i = 0; i < dirNames->Length; ++i )
            {

               // Delete the Archive directory.
               isoFile->DeleteDirectory( dirNames[ i ] );

            }
         }
         dirNames = isoFile->GetDirectoryNames( "*" );
         isoFile->Remove();
      }
      catch ( Exception^ e ) 
      {
         Console::WriteLine( e->ToString() );
      }

   }


   double SetNewPrefsForUser()
   {
      try
      {
         Byte inputChar;
         IsolatedStorageFile^ isoFile = IsolatedStorageFile::GetStore( static_cast<IsolatedStorageScope>(IsolatedStorageScope::User | IsolatedStorageScope::Assembly | IsolatedStorageScope::Domain), System::Security::Policy::Url::typeid, System::Security::Policy::Url::typeid );

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

               // This is the stream to which data will be written.
               IsolatedStorageFileStream^ source = gcnew IsolatedStorageFileStream( this->userName,FileMode::OpenOrCreate,isoFile );

               // This is the stream from which data will be read.
               Console::WriteLine( "Is the source file readable?  {0}", (source->CanRead ? (String^)"true" : "false") );
               Console::WriteLine( "Creating new IsolatedStorageFileStream for Archive." );

               // Open or create a writable file.
               IsolatedStorageFileStream^ target = gcnew IsolatedStorageFileStream( String::Concat("Archive\\",this->userName),FileMode::OpenOrCreate,FileAccess::Write,FileShare::Write,isoFile );

               Console::WriteLine( "Is the target file writable? {0}", (target->CanWrite ? (String^)"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( (Byte)source->ReadByte() );
                  }

                  // Determine the size of the IsolatedStorageFileStream 
                  // by checking its Length property.
                  Console::WriteLine( "Total Bytes Read: {0}", source->Length.ToString() );

               }

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

         // Open or create a writable file, no larger than 10k
         IsolatedStorageFileStream^ isoStream = gcnew IsolatedStorageFileStream( this->userName,FileMode::OpenOrCreate,FileAccess::Write,FileShare::Write,10240,isoFile );

         isoStream->Position = 0; // Position to overwrite the old data.

         StreamWriter^ writer = gcnew 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 = {0}", isoFile->CurrentSize.ToString() );
         Console::WriteLine( "MaximumSize = {0}", isoFile->MaximumSize.ToString() );

         // StreamWriter.Close implicitly closes isoStream.
         writer->Close();
         isoFile->Close();
         return d;
      }
      catch ( Exception^ e ) 
      {
         Console::WriteLine( e->ToString() );
         return 0.0;
      }

   }

   LoginPrefs( String^ aUserName )
   {
      userName = aUserName;
      newPrefs = GetPrefsForUser();
   }


   property String^ NewsUrl 
   {
      String^ get()
      {
         return newsUrl;
      }

      void set( String^ value )
      {
         newsUrl = value;
      }

   }

   property String^ SportsUrl 
   {
      String^ get()
      {
         return sportsUrl;
      }

      void set( String^ value )
      {
         sportsUrl = value;
      }

   }

   property bool NewPrefs 
   {
      bool get()
      {
         return newPrefs;
      }

   }

};

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();
}

int main()
{

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

   // Does no error checking.
   LoginPrefs^ lp = gcnew 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 {0}%", percentUsed );
   }
   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->Equals( "d" ) )
   {
      lp->DeleteFiles();
      lp->DeleteDirectories();
   }
}

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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