語言

FileInfo.OpenWrite 方法

定義

命名空間:
System.IO
組件:
mscorlib.dll, System.IO.FileSystem.dll
組件:
netstandard.dll, System.Runtime.dll
組件:
netstandard.dll, System.IO.FileSystem.dll
組件:
netstandard.dll, System.IO.FileSystem.dll, System.Runtime.dll
組件:
System.IO.FileSystem.dll
組件:
mscorlib.dll
組件:
netstandard.dll
來源:
FileInfo.cs
來源:
FileInfo.cs
來源:
FileInfo.cs
來源:
FileInfo.cs
來源:
FileInfo.cs

建立一個唯寫 FileStream。

public:
 System::IO::FileStream ^ OpenWrite();
public System.IO.FileStream OpenWrite();
member this.OpenWrite : unit -> System.IO.FileStream
Public Function OpenWrite () As FileStream

傳回

FileStream

一個只寫入且未共享 FileStream 的物件，用於新檔案或現有檔案。

例外狀況

UnauthorizedAccessException

建立物件實例 FileInfo 時指定的路徑是唯讀或為目錄。

DirectoryNotFoundException

建立物件實例 FileInfo 時指定的路徑是無效的，例如位於未映射的磁碟機上。

範例

以下範例會打開一個檔案進行寫入，然後從該檔案讀取。

using System;
using System.IO;
using System.Text;

class Test
{
    public static void Main()
    {
        string path = @"c:\Temp\MyTest.txt";
        FileInfo fi = new FileInfo(path);

        // Open the stream for writing.
        using (FileStream fs = fi.OpenWrite())
        {
            Byte[] info =
                new UTF8Encoding(true).GetBytes("This is to test the OpenWrite method.");

            // Add some information to the file.
            fs.Write(info, 0, info.Length);
        }

        // Open the stream and read it back.
        using (FileStream fs = fi.OpenRead())
        {
            byte[] b = new byte[1024];
            UTF8Encoding temp = new UTF8Encoding(true);

            while (fs.Read(b,0,b.Length) > 0)
            {
                Console.WriteLine(temp.GetString(b));
            }
        }
    }
}
//This code produces output similar to the following;
//This is to test the OpenWrite method.

Imports System.IO
Imports System.Text

Public Class Test
    Public Shared Sub Main()
        Dim path As String = "c:\Temp\MyTest.txt"
        Dim fi As FileInfo = New FileInfo(path)
        Dim fs As FileStream

        ' Open the stream for writing.
        fs = fi.OpenWrite()
        Dim info As Byte() = _
            New UTF8Encoding(True).GetBytes("This is to test the OpenWrite method.")

        ' Add some information to the file.
        fs.Write(info, 0, info.Length)
        fs.Close()

        'Open the stream and read it back.
        fs = fi.OpenRead()
        Dim b(1023) As Byte
        Dim temp As UTF8Encoding = New UTF8Encoding(True)

        Do While fs.Read(b, 0, b.Length) > 0
            Console.WriteLine(temp.GetString(b))
        Loop
        fs.Close()
    End Sub
End Class
'This code produces output similar to the following; 
'results may vary based on the computer/file structure/etc.:
'
'This is to test the OpenWrite method.
'
'
'
'
'
'
'
'
'
'
'
'

備註

若該路徑已有檔案，則 OpenWrite 開啟該方法;若不存在，則建立新檔案。 對於現有檔案，它不會將新文字附加到現有文字上。 相反地，它會用新角色覆蓋現有角色。 如果你用較短的字串（例如「Second run」）覆蓋較長的字串（例如「Second run」），檔案中會包含多個字串的混合（「OpenWrite 方法的第二次測試」）。

適用於