Stream.CanRead 属性

定义

当在派生类中重写时,获取指示当前流是否支持读取的值。When overridden in a derived class, gets a value indicating whether the current stream supports reading.

public:
 abstract property bool CanRead { bool get(); };
public abstract bool CanRead { get; }
member this.CanRead : bool
Public MustOverride ReadOnly Property CanRead As Boolean

属性值

如果流支持读取,为 true;否则为 falsetrue if the stream supports reading; otherwise, false.

示例

下面是使用CanRead属性的示例。The following is an example of using the CanRead property.

using namespace System;
using namespace System::IO;
int main( void )
{
   FileStream^ fs = gcnew FileStream( "MyFile.txt",FileMode::OpenOrCreate,FileAccess::Read );
   if ( fs->CanRead && fs->CanWrite )
   {
      Console::WriteLine( "MyFile.txt can be both written to and read from." );
   }
   else
   {
      Console::WriteLine( "MyFile.txt is not writable" );
   }

   return 0;
}

using System;
using System.IO;
 
class TestRW 
{
    public static void Main(String[] args)
    {
        FileStream fs = new FileStream("MyFile.txt", FileMode.OpenOrCreate, FileAccess.Read);
        if (fs.CanRead && fs.CanWrite)
        {
            Console.WriteLine("MyFile.txt can be both written to and read from.");
        }
        else if (fs.CanRead)
        {
            Console.WriteLine("MyFile.txt is not writable.");
        }
    }
}
Imports System.IO

Class TestRW

    Public Shared Sub Main()
        Dim fs As New FileStream("MyFile.txt", FileMode.OpenOrCreate, FileAccess.Read)
        If fs.CanRead And fs.CanWrite Then
            Console.WriteLine("MyFile.txt can be both written to and read from.")
        Else
            If fs.CanRead Then
                Console.WriteLine("MyFile.txt is not writable.")
            End If
        End If
    End Sub
End Class

注解

如果Stream从派生的类不支持读取,则对、 ReadByteRead BeginRead方法的调用将引发NotSupportedExceptionIf a class derived from Stream does not support reading, calls to the Read, ReadByte, and BeginRead methods throw a NotSupportedException.

如果流已关闭, 则此属性返回falseIf the stream is closed, this property returns false.

适用于

另请参阅