FileInfo.IsReadOnly Свойство

Определение

Пространство имен:: System.IO

Сборки:: System.IO.FileSystem.dll, mscorlib.dll, netstandard.dll

Возвращает или задает значение, позволяющее определить, является ли текущий файл доступным только для чтения.Gets or sets a value that determines if the current file is read only.

public:
 property bool IsReadOnly { bool get(); void set(bool value); };

public bool IsReadOnly { get; set; }

member this.IsReadOnly : bool with get, set

Public Property IsReadOnly As Boolean

Значение свойства

Boolean

Значение true, если текущий файл доступен только для чтения; в противном случае — значение false.true if the current file is read only; otherwise, false.

Исключения

FileNotFoundException

Не удалось найти файл, описанный текущим объектом FileInfo.The file described by the current FileInfo object could not be found.

IOException

При открытии файла произошла ошибка ввода-вывода.An I/O error occurred while opening the file.

UnauthorizedAccessException

Эта операция не поддерживается на текущей платформе.This operation is not supported on the current platform.

- или --or-

У вызывающего объекта отсутствует необходимое разрешение.The caller does not have the required permission.

ArgumentException

Пользователь не имеет разрешения на запись, но пытается задать для этого свойства значение false.The user does not have write permission, but attempted to set this property to false.

Примеры

В следующем примере IsReadOnly свойство используется, чтобы пометить файл как доступный только для чтения, а затем пометить его как доступный для чтения и записи.The following example uses the IsReadOnly property to mark a file as read only and then mark it as read-write.

using namespace System;
using namespace System::IO;

namespace FileSystemExample
{
    // Sets the read-only value of a file.
    void SetFileReadAccess(String^ fileName, bool setReadOnly)
    {
        // Create a new FileInfo object.
        FileInfo^ fInfo = gcnew FileInfo(fileName);

        // Set the IsReadOnly property.
        fInfo->IsReadOnly = setReadOnly;
    }

    // Returns whether a file is read-only.
    bool IsFileReadOnly(String^ fileName)
    {
        // Create a new FileInfo object.
        FileInfo^ fInfo = gcnew FileInfo(fileName);

        // Return the IsReadOnly property value.
        return fInfo->IsReadOnly;
    }
}

int main()
{
    try
    {
        String^ fileName = "c:\\test.xml";

        if (File::Exists(fileName))
        {
            // Get the read-only value for a file.
            bool isReadOnly = FileSystemExample::IsFileReadOnly(fileName);

            // Display whether the file is read-only.
            Console::WriteLine("The file read-only value for {0} is:" +
                "{1}", fileName, isReadOnly);

            Console::WriteLine("Changing the read-only value for {0}" +
                " to true.", fileName);

            // Set the file to read-only.
            FileSystemExample::SetFileReadAccess(fileName, true);

            // Get the read-only value for a file.
            isReadOnly = FileSystemExample::IsFileReadOnly(fileName);

            // Display that the file is read-only.
            Console::WriteLine("The file read-only value for {0} is:" +
                "{1}", fileName, isReadOnly);
        }
        else
        {
            Console::WriteLine("The file {0} doesn't exist.", fileName);
        }
    }
    catch (IOException^ ex)
    {
        Console::WriteLine(ex->Message);
    }
};
//This code produces output similar to the following; 
//results may vary based on the computer/file structure/etc.:
//
//The file read-only value for c:\test.xml is:False
//Changing the read-only value for c:\test.xml to true.
//The file read-only value for c:\test.xml is:True

using System;
using System.IO;

namespace FileSystemExample
{
    class FileExample
    {
        public static void Main()
        {

            string FileName = @"c:\test.xml";

            // Get the read-only value for a file.
            bool isReadOnly = IsFileReadOnly(FileName);

            // Display wether the file is read-only.
            Console.WriteLine("The file read-only value for " + FileName + " is: " + isReadOnly);

            Console.WriteLine("Changing the read-only value for " + FileName + " to true.");

            // Set the file to read-only.
            SetFileReadAccess(FileName, true);

            // Get the read-only value for a file.
            isReadOnly = IsFileReadOnly(FileName);

            // Display that the file is read-only.
            Console.WriteLine("The file read-only value for " + FileName + " is: " + isReadOnly);


        }

        // Sets the read-only value of a file.
        public static void SetFileReadAccess(string FileName, bool SetReadOnly)
        {
            // Create a new FileInfo object.
            FileInfo fInfo = new FileInfo(FileName);

            // Set the IsReadOnly property.
            fInfo.IsReadOnly = SetReadOnly;

        }

        // Returns wether a file is read-only.
        public static bool IsFileReadOnly(string FileName)
        {
            // Create a new FileInfo object.
            FileInfo fInfo = new FileInfo(FileName);

            // Return the IsReadOnly property value.
            return fInfo.IsReadOnly;

        }

    }
}

//This code produces output similar to the following; 
//results may vary based on the computer/file structure/etc.:
//
//The file read-only value for c:\test.xml is: True
//Changing the read-only value for c:\test.xml to true.
//The file read-only value for c:\test.xml is: True
//

Imports System.IO



Module FileExample

    Sub Main()

        Dim FileName As String = "c:\test.xml"

        ' Get the read-only value for a file.
        Dim isReadOnly As Boolean = IsFileReadOnly(FileName)

        ' Display wether the file is read-only.
        Console.WriteLine("The file read-only value for " & FileName & " is: " & isReadOnly)

        Console.WriteLine("Changing the read-only value for " & FileName & " to true.")

        ' Set the file to read-only.
        SetFileReadAccess(FileName, True)

        ' Get the read-only value for a file.
        isReadOnly = IsFileReadOnly(FileName)

        ' Display that the file is read-only.
        Console.WriteLine("The file read-only value for " & FileName & " is: " & isReadOnly)

    End Sub


    ' Sets the read-only value of a file.
    Sub SetFileReadAccess(ByVal FileName As String, ByVal SetReadOnly As Boolean)
        ' Create a new FileInfo object.
        Dim fInfo As New FileInfo(FileName)

        ' Set the IsReadOnly property.
        fInfo.IsReadOnly = SetReadOnly

    End Sub


    ' Returns wether a file is read-only.
    Function IsFileReadOnly(ByVal FileName As String) As Boolean
        ' Create a new FileInfo object.
        Dim fInfo As New FileInfo(FileName)

        ' Return the IsReadOnly property value.
        Return fInfo.IsReadOnly

    End Function
End Module
'This code produces output similar to the following; 
'results may vary based on the computer/file structure/etc.:
'
'The file read-only value for c:\test.xml is: True
'Changing the read-only value for c:\test.xml to true.
'The file read-only value for c:\test.xml is: True

При первом вызове FileInfo вызывает Refresh и кэширует сведения о файле.When first called, FileInfo calls Refresh and caches information about the file. При последующих вызовах необходимо вызвать Refresh , чтобы получить последнюю копию информации.On subsequent calls, you must call Refresh to get the latest copy of the information.

Безопасность

FileIOPermission
Связанные перечисления: Read,WriteAssociated enumerations: Read, Write Действие по обеспечению безопасности: Вызов.Security action: Demand. Разрешение на чтение и запись в файл, описываемый текущим FileInfo объектом.For permission to read and write to the file described by the current FileInfo object.