FileStream.Unlock(Int64, Int64) Método
Definição
Importante
Algumas informações se referem a produtos de pré-lançamento que podem ser substancialmente modificados antes do lançamento. A Microsoft não oferece garantias, expressas ou implícitas, das informações aqui fornecidas.
Permite o acesso por outros processos a todo ou parte de um arquivo que foi bloqueado anteriormente.
public:
virtual void Unlock(long position, long length);public virtual void Unlock (long position, long length);[System.Runtime.Versioning.UnsupportedOSPlatform("ios")]
[System.Runtime.Versioning.UnsupportedOSPlatform("macos")]
[System.Runtime.Versioning.UnsupportedOSPlatform("tvos")]
public virtual void Unlock (long position, long length);[System.Runtime.Versioning.UnsupportedOSPlatform("ios")]
[System.Runtime.Versioning.UnsupportedOSPlatform("macos")]
[System.Runtime.Versioning.UnsupportedOSPlatform("tvos")]
[System.Runtime.Versioning.UnsupportedOSPlatform("freebsd")]
public virtual void Unlock (long position, long length);abstract member Unlock : int64 * int64 -> unit
override this.Unlock : int64 * int64 -> unit[<System.Runtime.Versioning.UnsupportedOSPlatform("ios")>]
[<System.Runtime.Versioning.UnsupportedOSPlatform("macos")>]
[<System.Runtime.Versioning.UnsupportedOSPlatform("tvos")>]
abstract member Unlock : int64 * int64 -> unit
override this.Unlock : int64 * int64 -> unit[<System.Runtime.Versioning.UnsupportedOSPlatform("ios")>]
[<System.Runtime.Versioning.UnsupportedOSPlatform("macos")>]
[<System.Runtime.Versioning.UnsupportedOSPlatform("tvos")>]
[<System.Runtime.Versioning.UnsupportedOSPlatform("freebsd")>]
abstract member Unlock : int64 * int64 -> unit
override this.Unlock : int64 * int64 -> unitPublic Overridable Sub Unlock (position As Long, length As Long)Parâmetros
- position
- Int64
O início do intervalo a ser desbloqueado.
- length
- Int64
O intervalo a ser desbloqueado.
- Atributos
Exceções
position ou length é negativo.
Exemplos
O exemplo de código a seguir demonstra como bloquear parte de um arquivo para que outro processo não possa acessar essa parte do arquivo, mesmo que ele tenha acesso de leitura/gravação ao arquivo e desbloqueie a parte especificada do arquivo . Execute o programa simultaneamente em janelas de comando diferentes e investigue usando as diferentes opções de entrada do console.
using namespace System;
using namespace System::IO;
using namespace System::Text;
int main()
{
UnicodeEncoding^ uniEncoding = gcnew UnicodeEncoding;
String^ lastRecordText = "The last processed record number was: ";
int textLength = uniEncoding->GetByteCount( lastRecordText );
int recordNumber = 13;
int byteCount = uniEncoding->GetByteCount( recordNumber.ToString() );
String^ tempString;
FileStream^ fileStream = gcnew FileStream( "Test#@@#.dat",FileMode::OpenOrCreate,FileAccess::ReadWrite,FileShare::ReadWrite );
try
{
// Write the original file data.
if ( fileStream->Length == 0 )
{
tempString = String::Concat( lastRecordText, recordNumber.ToString() );
fileStream->Write( uniEncoding->GetBytes( tempString ), 0, uniEncoding->GetByteCount( tempString ) );
}
// Allow the user to choose the operation.
Char consoleInput = 'R';
array<Byte>^readText = gcnew array<Byte>(fileStream->Length);
while ( consoleInput != 'X' )
{
Console::Write( "\nEnter 'R' to read, 'W' to write, 'L' to "
"lock, 'U' to unlock, anything else to exit: " );
if ( (tempString = Console::ReadLine())->Length == 0 )
{
break;
}
consoleInput = Char::ToUpper( tempString[0] );
switch ( consoleInput )
{
case 'R':
try
{
fileStream->Seek( 0, SeekOrigin::Begin );
fileStream->Read( readText, 0, (int)fileStream->Length );
tempString = gcnew String( uniEncoding->GetChars( readText, 0, readText->Length ) );
Console::WriteLine( tempString );
recordNumber = Int32::Parse( tempString->Substring( tempString->IndexOf( ':' ) + 2 ) );
}
// Catch the IOException generated if the
// specified part of the file is locked.
catch ( IOException^ e )
{
Console::WriteLine( "{0}: The read "
"operation could not be performed "
"because the specified part of the "
"file is locked.", e->GetType()->Name );
}
break;
// Update the file.
case 'W':
try
{
fileStream->Seek( textLength, SeekOrigin::Begin );
fileStream->Read( readText, textLength - 1, byteCount );
tempString = gcnew String( uniEncoding->GetChars( readText, textLength - 1, byteCount ) );
recordNumber = Int32::Parse( tempString ) + 1;
fileStream->Seek( textLength, SeekOrigin::Begin );
fileStream->Write( uniEncoding->GetBytes( recordNumber.ToString() ), 0, byteCount );
fileStream->Flush();
Console::WriteLine( "Record has been updated." );
}
// Catch the IOException generated if the
// specified part of the file is locked.
catch ( IOException^ e )
{
Console::WriteLine( "{0}: The write operation could not "
"be performed because the specified "
"part of the file is locked.", e->GetType()->Name );
}
break;
// Lock the specified part of the file.
case 'L':
try
{
fileStream->Lock( textLength - 1, byteCount );
Console::WriteLine( "The specified part "
"of file has been locked." );
}
catch ( IOException^ e )
{
Console::WriteLine( "{0}: The specified part of file is"
" already locked.", e->GetType()->Name );
}
break;
// Unlock the specified part of the file.
case 'U':
try
{
fileStream->Unlock( textLength - 1, byteCount );
Console::WriteLine( "The specified part "
"of file has been unlocked." );
}
catch ( IOException^ e )
{
Console::WriteLine( "{0}: The specified part of file is "
"not locked by the current process.", e->GetType()->Name );
}
break;
default:
// Exit the program.
consoleInput = 'X';
break;
}
}
}
finally
{
fileStream->Close();
}
}
using System;
using System.IO;
using System.Text;
class FStreamLock
{
static void Main()
{
UnicodeEncoding uniEncoding = new UnicodeEncoding();
string lastRecordText =
"The last processed record number was: ";
int textLength = uniEncoding.GetByteCount(lastRecordText);
int recordNumber = 13;
int byteCount =
uniEncoding.GetByteCount(recordNumber.ToString());
string tempString;
using(FileStream fileStream = new FileStream(
"Test#@@#.dat", FileMode.OpenOrCreate,
FileAccess.ReadWrite, FileShare.ReadWrite))
{
// Write the original file data.
if(fileStream.Length == 0)
{
tempString =
lastRecordText + recordNumber.ToString();
fileStream.Write(uniEncoding.GetBytes(tempString),
0, uniEncoding.GetByteCount(tempString));
}
// Allow the user to choose the operation.
char consoleInput = 'R';
byte[] readText = new byte[fileStream.Length];
while(consoleInput != 'X')
{
Console.Write(
"\nEnter 'R' to read, 'W' to write, 'L' to " +
"lock, 'U' to unlock, anything else to exit: ");
if((tempString = Console.ReadLine()).Length == 0)
{
break;
}
consoleInput = char.ToUpper(tempString[0]);
switch(consoleInput)
{
// Read data from the file and
// write it to the console.
case 'R':
try
{
fileStream.Seek(0, SeekOrigin.Begin);
fileStream.Read(
readText, 0, (int)fileStream.Length);
tempString = new String(
uniEncoding.GetChars(
readText, 0, readText.Length));
Console.WriteLine(tempString);
recordNumber = int.Parse(
tempString.Substring(
tempString.IndexOf(':') + 2));
}
// Catch the IOException generated if the
// specified part of the file is locked.
catch(IOException e)
{
Console.WriteLine("{0}: The read " +
"operation could not be performed " +
"because the specified part of the " +
"file is locked.",
e.GetType().Name);
}
break;
// Update the file.
case 'W':
try
{
fileStream.Seek(textLength,
SeekOrigin.Begin);
fileStream.Read(
readText, textLength - 1, byteCount);
tempString = new String(
uniEncoding.GetChars(
readText, textLength - 1, byteCount));
recordNumber = int.Parse(tempString) + 1;
fileStream.Seek(
textLength, SeekOrigin.Begin);
fileStream.Write(uniEncoding.GetBytes(
recordNumber.ToString()),
0, byteCount);
fileStream.Flush();
Console.WriteLine(
"Record has been updated.");
}
// Catch the IOException generated if the
// specified part of the file is locked.
catch(IOException e)
{
Console.WriteLine(
"{0}: The write operation could not " +
"be performed because the specified " +
"part of the file is locked.",
e.GetType().Name);
}
break;
// Lock the specified part of the file.
case 'L':
try
{
fileStream.Lock(textLength - 1, byteCount);
Console.WriteLine("The specified part " +
"of file has been locked.");
}
catch(IOException e)
{
Console.WriteLine(
"{0}: The specified part of file is" +
" already locked.", e.GetType().Name);
}
break;
// Unlock the specified part of the file.
case 'U':
try
{
fileStream.Unlock(
textLength - 1, byteCount);
Console.WriteLine("The specified part " +
"of file has been unlocked.");
}
catch(IOException e)
{
Console.WriteLine(
"{0}: The specified part of file is " +
"not locked by the current process.",
e.GetType().Name);
}
break;
// Exit the program.
default:
consoleInput = 'X';
break;
}
}
}
}
}
open System
open System.IO
open System.Text
let uniEncoding = UnicodeEncoding()
let lastRecordText = "The last processed record number was: "
let textLength = uniEncoding.GetByteCount lastRecordText
let mutable recordNumber = 13
let byteCount = string recordNumber |> uniEncoding.GetByteCount
do
use fileStream =
new FileStream("Test#@@#.dat", FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite)
// Write the original file data.
if fileStream.Length = 0 then
let tempString = lastRecordText + string recordNumber
fileStream.Write(uniEncoding.GetBytes tempString, 0, uniEncoding.GetByteCount tempString)
// Allow the user to choose the operation.
let mutable consoleInput = 'R'
let readText = int fileStream.Length |> Array.zeroCreate
while consoleInput <> 'X' do
printf "\nEnter 'R' to read, 'W' to write, 'L' to lock, 'U' to unlock, anything else to exit: "
let mutable tempString = stdin.ReadLine()
if tempString.Length = 0 then
consoleInput <- 'X'
else
consoleInput <- Char.ToUpper tempString[0]
match consoleInput with
| 'R' ->
// Read data from the file and
// write it to the console.
try
fileStream.Seek(0, SeekOrigin.Begin) |> ignore
fileStream.Read(readText, 0, int fileStream.Length) |> ignore
tempString <- String(uniEncoding.GetChars readText, 0, readText.Length)
printfn $"{tempString}"
recordNumber <- tempString.IndexOf ':' + 2 |> tempString.Substring |> Int32.Parse
// Catch the IOException generated if the
// specified part of the file is locked.
with :? IOException as e ->
printfn
$"{e.GetType().Name}: The read operation could not be performed because the specified part of the file is locked."
| 'W' ->
// Update the file.
try
fileStream.Seek(textLength, SeekOrigin.Begin) |> ignore
fileStream.Read(readText, textLength - 1, byteCount) |> ignore
tempString <- String(uniEncoding.GetChars readText, textLength - 1, byteCount)
recordNumber <- Int32.Parse tempString + 1
fileStream.Seek(textLength, SeekOrigin.Begin) |> ignore
fileStream.Write(string recordNumber |> uniEncoding.GetBytes, 0, byteCount)
fileStream.Flush()
printfn "Record has been updated."
// Catch the IOException generated if the
// specified part of the file is locked.
with :? IOException as e ->
printfn
$"{e.GetType().Name}: The write operation could not be performed because the specified part of the file is locked."
// Lock the specified part of the file.
| 'L' ->
try
fileStream.Lock(textLength - 1 |> int64, byteCount)
printfn "The specified part of file has been locked."
with :? IOException as e ->
printfn $"{e.GetType().Name}: The specified part of file is already locked."
// Unlock the specified part of the file.
| 'U' ->
try
fileStream.Unlock(textLength - 1 |> int64, byteCount)
printfn "The specified part of file has been unlocked."
with :? IOException as e ->
printfn $"{e.GetType().Name}: The specified part of file is not locked by the current process."
// Exit the program.
| _ -> consoleInput <- 'X'
Imports System.IO
Imports System.Text
Public Class FStreamLock
Shared Sub Main()
Dim uniEncoding As New UnicodeEncoding()
Dim lastRecordText As String = _
"The last processed record number was: "
Dim textLength As Integer = _
uniEncoding.GetByteCount(lastRecordText)
Dim recordNumber As Integer = 13
Dim byteCount As Integer = _
uniEncoding.GetByteCount(recordNumber.ToString())
Dim tempString As String
Dim aFileStream As New FileStream( _
"Test#@@#.dat", FileMode.OpenOrCreate, _
FileAccess.ReadWrite, FileShare.ReadWrite)
Try
' Write the original file data.
If aFileStream.Length = 0 Then
tempString = _
lastRecordText + recordNumber.ToString()
aFileStream.Write(uniEncoding.GetBytes(tempString), _
0, uniEncoding.GetByteCount(tempString))
End If
' Allow the user to choose the operation.
Dim consoleInput As Char = "R"C
Dim readText(CInt(aFileStream.Length)) As Byte
While consoleInput <> "X"C
Console.Write(vbcrLf & _
"Enter 'R' to read, 'W' to write, 'L' to " & _
"lock, 'U' to unlock, anything else to exit: ")
tempString = Console.ReadLine()
If tempString.Length = 0 Then
Exit While
End If
consoleInput = Char.ToUpper(tempString.Chars(0))
Select consoleInput
' Read data from the file and
' write it to the console.
Case "R"C
Try
aFileStream.Seek(0, SeekOrigin.Begin)
aFileStream.Read( _
readText, 0, CInt(aFileStream.Length))
tempString = New String( _
uniEncoding.GetChars( _
readText, 0, readText.Length))
Console.WriteLine(tempString)
recordNumber = Integer.Parse( _
tempString.Substring( _
tempString.IndexOf(":"C) + 2))
' Catch the IOException generated if the
' specified part of the file is locked.
Catch ex As IOException
Console.WriteLine("{0}: The read " & _
"operation could not be performed " & _
"because the specified part of the" & _
" file is locked.", _
ex.GetType().Name)
End Try
Exit Select
' Update the file.
Case "W"C
Try
aFileStream.Seek(textLength, _
SeekOrigin.Begin)
aFileStream.Read( _
readText, textLength - 1, byteCount)
tempString = New String( _
uniEncoding.GetChars( _
readText, textLength - 1, byteCount))
recordNumber = _
Integer.Parse(tempString) + 1
aFileStream.Seek( _
textLength, SeekOrigin.Begin)
aFileStream.Write(uniEncoding.GetBytes( _
recordNumber.ToString()), 0, byteCount)
aFileStream.Flush()
Console.WriteLine( _
"Record has been updated.")
' Catch the IOException generated if the
' specified part of the file is locked.
Catch ex As IOException
Console.WriteLine( _
"{0}: The write operation could " & _
"not be performed because the " & _
"specified part of the file is " & _
"locked.", ex.GetType().Name)
End Try
Exit Select
' Lock the specified part of the file.
Case "L"C
Try
aFileStream.Lock(textLength - 1, byteCount)
Console.WriteLine("The specified part " & _
"of file has been locked.")
Catch ex As IOException
Console.WriteLine( _
"{0}: The specified part of file " & _
"is already locked.", _
ex.GetType().Name)
End Try
Exit Select
' Unlock the specified part of the file.
Case "U"C
Try
aFileStream.Unlock( _
textLength - 1, byteCount)
Console.WriteLine("The specified part " & _
"of file has been unlocked.")
Catch ex As IOException
Console.WriteLine( _
"{0}: The specified part of file " & _
"is not locked by the current " & _
"process.", ex.GetType().Name)
End Try
Exit Select
' Exit the program.
Case Else
consoleInput = "X"C
Exit While
End Select
End While
Finally
aFileStream.Close()
End Try
End Sub
End Class
Comentários
Para obter uma lista de operações comuns de arquivo e diretório, consulte Tarefas comuns de E/S.
Aplica-se a
Confira também
Colabore connosco no GitHub
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