FileStream.CanRead 属性

定义

命名空间:
System.IO
程序集:
mscorlib.dll, System.IO.FileSystem.dll
程序集:
mscorlib.dll
程序集:
System.IO.FileSystem.dll
程序集:
netstandard.dll

获取一个值，该值指示当前流是否支持读取。

public:
 virtual property bool CanRead { bool get(); };
public override bool CanRead { get; }
member this.CanRead : bool
Public Overrides ReadOnly Property CanRead As Boolean

属性值

Boolean

true 如果流支持读取，则为 false 如果流已关闭或已使用仅写访问权限打开。

示例

下面的示例演示了该 CanRead 属性的使用。 此代码的输出为“MyFile.txt 不可写”。若要获取输出消息“MyFile.txt 可以写入和读取。”，请将 FileAccess 参数更改为 ReadWrite 构造函数中的 FileStream 参数。

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.");
        }
    }
}

open System.IO

let fs = new FileStream("MyFile.txt", FileMode.OpenOrCreate, FileAccess.Read)

if fs.CanRead && fs.CanWrite then
    printfn "MyFile.txt can be both written to and read from."
else if fs.CanRead then
    printfn "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

如果派生自的类不支持读取，则对 <a0/> 的调用和方法将引发一个。

如果流已关闭，则此属性返回 false。

适用于

另请参阅