File.Open 方法

參考

定義

命名空間:: System.IO

組件:: mscorlib.dll, System.IO.FileSystem.dll

組件:: System.IO.FileSystem.dll

組件:: System.Runtime.dll

組件:: mscorlib.dll

組件:: netstandard.dll

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

在指定路徑上開啟 FileStream。

多載

Open(String, FileMode, FileAccess, FileShare)	在指定路徑上開啟 FileStream，假定它具有讀取、寫入或讀取/寫入存取的指定模式和指定的共用選項。
Open(String, FileMode)	在指定路徑上開啟具有讀取/寫入權限且不共用的 FileStream。
Open(String, FileStreamOptions)	使用指定的路徑、建立模式、讀取/寫入和共用許可權，初始化類別的新實例 FileStream ，其他 FileStreams 可以擁有相同的檔案、緩衝區大小、其他檔案選項和配置大小。
Open(String, FileMode, FileAccess)	在指定路徑上開啟具有指定模式和存取權且不共用的 FileStream。

Open(String, FileMode, FileAccess, FileShare)

來源:: File.cs

來源:: File.cs

來源:: File.cs

在指定路徑上開啟 FileStream，假定它具有讀取、寫入或讀取/寫入存取的指定模式和指定的共用選項。

public:
 static System::IO::FileStream ^ Open(System::String ^ path, System::IO::FileMode mode, System::IO::FileAccess access, System::IO::FileShare share);

public static System.IO.FileStream Open (string path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share);

static member Open : string * System.IO.FileMode * System.IO.FileAccess * System.IO.FileShare -> System.IO.FileStream

Public Shared Function Open (path As String, mode As FileMode, access As FileAccess, share As FileShare) As FileStream

參數

path: String

要開啟的檔案。

mode: FileMode

FileMode 值，指定是否要建立檔案 (如果不存在的話)，以及決定要保留或覆寫現有檔案的內容。

access: FileAccess

FileAccess 值，指定可以在檔案上執行的作業。

share: FileShare

FileShare 值，指定其他執行緒對檔案擁有的存取類型。

傳回

FileStream

指定路徑上的 FileStream，假定它具有讀取、寫入或讀取/寫入存取的指定模式和指定的共用選項。

例外狀況

ArgumentException

.NET Framework 和 2.1 之前的 .NET Core 版本：path是長度為零的字串、只包含空格符，或包含一或多個無效字元。您可以使用 GetInvalidPathChars() 方法查詢無效字元。

-或-

access 指定了 Read，而 mode 指定了 Create、CreateNew、Truncate 或 Append。

ArgumentNullException

path 為 null。

PathTooLongException

指定的路徑、檔案名稱，或兩者都超出系統定義的長度上限。

DirectoryNotFoundException

指定的路徑無效 (例如，它位於未對應的磁碟機上)。

IOException

開啟檔案時發生 I/O 錯誤。

UnauthorizedAccessException

path 指定了唯讀檔案，而 access 不是 Read。

-或-

path 指定了目錄。

-或-

呼叫端沒有必要的權限。

-或-

mode 是 Create，且指定的檔案是隱藏檔案。

ArgumentOutOfRangeException

mode、access 或 share 指定了無效的值。

FileNotFoundException

找不到 path 指定的檔案。

NotSupportedException

path 格式無效。

範例

下列範例會開啟具有唯讀存取權且不允許檔案共享的檔案。

using namespace System;
using namespace System::IO;
using namespace System::Text;

int main()
{
   String^ path = "c:\\temp\\MyTest.txt";
   
   // Create the file if it does not exist.
   if (  !File::Exists( path ) )
   {
      // Create the file.
      FileStream^ fs = File::Create( path );
      try
      {
         array<Byte>^info = (gcnew UTF8Encoding( true ))->GetBytes( "This is some text in the file." );
         
         // Add some information to the file.
         fs->Write( info, 0, info->Length );
      }
      finally
      {
         if ( fs )
                  delete (IDisposable^)fs;
      }
   }
   
   // Open the stream and read it back.
   FileStream^ fs = File::Open( path, FileMode::Open, FileAccess::Read, FileShare::None );
   try
   {
      array<Byte>^b = gcnew array<Byte>(1024);
      UTF8Encoding^ temp = gcnew UTF8Encoding( true );
      while ( fs->Read( b, 0, b->Length ) > 0 )
      {
         Console::WriteLine( temp->GetString( b ) );
      }
      try
      {
         // Try to get another handle to the same file.
         FileStream^ fs2 = File::Open( path, FileMode::Open );
         try
         {
            // Do some task here.
         }
         finally
         {
            if ( fs2 )
                        delete (IDisposable^)fs2;
         }
      }
      catch ( Exception^ e ) 
      {
         Console::Write( "Opening the file twice is disallowed." );
         Console::WriteLine( ", as expected: {0}", e );
      }
   }
   finally
   {
      if ( fs )
            delete (IDisposable^)fs;
   }
}

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

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

        // Create the file if it does not exist.
        if (!File.Exists(path))
        {
            // Create the file.
            using (FileStream fs = File.Create(path))
            {
                Byte[] info = new UTF8Encoding(true).GetBytes("This is some text in the file.");

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

        // Open the stream and read it back.
        using (FileStream fs = File.Open(path, FileMode.Open, FileAccess.Read, FileShare.None))
        {
            byte[] b = new byte[1024];
            UTF8Encoding temp = new UTF8Encoding(true);

            while (fs.Read(b,0,b.Length) > 0)
            {
                Console.WriteLine(temp.GetString(b));
            }

            try
            {
                // Try to get another handle to the same file.
                using (FileStream fs2 = File.Open(path, FileMode.Open))
                {
                    // Do some task here.
                }
            }
            catch (Exception e)
            {
                Console.Write("Opening the file twice is disallowed.");
                Console.WriteLine(", as expected: {0}", e.ToString());
            }
        }
    }
}

open System.IO
open System.Text

let path = @"c:\temp\MyTest.txt"

// Create the file if it does not exist.
if File.Exists path |> not then
    // Create the file.
    use fs = File.Create path

    let info =
        UTF8Encoding(true)
            .GetBytes "This is some text in the file."

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

// Open the stream and read it back.
do
    use fs =
        File.Open(path, FileMode.Open, FileAccess.Read, FileShare.None)

    let b = Array.zeroCreate 1024
    let temp = UTF8Encoding true

    while fs.Read(b, 0, b.Length) > 0 do
        printfn $"{temp.GetString b}"

    try
        // Try to get another handle to the same file.
        use fs2 = File.Open(path, FileMode.Open)
        // Do some task here.
        ()
    with
    | e -> printf "Opening the file twice is disallowed, as expected: {e}"

Imports System.IO
Imports System.Text

Public Class Test
  Public Shared Sub Main()
    Dim path As String = "c:\temp\MyTest.txt"

    ' Create the file if it does not exist. 
    If Not File.Exists(path) Then
      ' Create the file.
      Using fs As FileStream = File.Create(path)
        Dim info As Byte() = New UTF8Encoding(True).GetBytes("This is some text in the file.")

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

    ' Open the stream and read it back.
    Using fs As FileStream = File.Open(path, FileMode.Open, FileAccess.Read, FileShare.None)
      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

      Try
        ' Try to get another handle to the same file. 
        Using fs2 As FileStream = File.Open(path, FileMode.Open)
          ' Do some task here.
        End Using
      Catch e As Exception
        Console.Write("Opening the file twice is disallowed.")
        Console.WriteLine(", as expected: {0}", e.ToString())
      End Try

    End Using

  End Sub
End Class

備註

允許 path 參數指定相對或絕對路徑資訊。相對路徑資訊會解譯為相對於目前工作目錄。若要取得目前的工作目錄，請參閱 GetCurrentDirectory。

如需一般 I/O 工作的清單，請參閱一般 I/O 工作。

另請參閱

適用於

Open(String, FileMode)

來源:: File.cs

來源:: File.cs

來源:: File.cs

在指定路徑上開啟具有讀取/寫入權限且不共用的 FileStream。

public:
 static System::IO::FileStream ^ Open(System::String ^ path, System::IO::FileMode mode);

public static System.IO.FileStream Open (string path, System.IO.FileMode mode);

static member Open : string * System.IO.FileMode -> System.IO.FileStream

Public Shared Function Open (path As String, mode As FileMode) As FileStream

參數

path: String

要開啟的檔案。

mode: FileMode

FileMode 值，指定是否要建立檔案 (如果不存在的話)，以及決定要保留或覆寫現有檔案的內容。

傳回

FileStream

在指定模式和路徑中開啟的 FileStream，具有讀取/寫入存取而且不共用。

例外狀況

ArgumentException

ArgumentNullException

path 為 null。

PathTooLongException

指定的路徑、檔案名稱，或兩者都超出系統定義的長度上限。

DirectoryNotFoundException

指定的路徑無效 (例如，它位於未對應的磁碟機上)。

IOException

開啟檔案時發生 I/O 錯誤。

UnauthorizedAccessException

path 指定了唯讀的檔案。

-或-

這個作業在目前平台不受支援。

-或-

path 指定了目錄。

-或-

呼叫端沒有必要的權限。

-或-

mode 是 Create，且指定的檔案是隱藏檔案。

ArgumentOutOfRangeException

mode 指定了無效的值。

FileNotFoundException

找不到 path 指定的檔案。

NotSupportedException

path 格式無效。

範例

下列程式代碼範例會建立臨時檔，並將一些文字寫入其中。範例接著會使用 T：System.IO.FileMode.Open 開啟檔案;也就是說，如果檔案尚未存在，則不會建立它。

using namespace System;
using namespace System::IO;
using namespace System::Text;

int main()
{
   // Create a temporary file, and put some data into it.
   String^ path = Path::GetTempFileName();
   FileStream^ fs = File::Open( path, FileMode::Open, FileAccess::Write, FileShare::None );
   try
   {
      array<Byte>^info = (gcnew UTF8Encoding( true ))->GetBytes( "This is some text in the file." );
      
      // Add some information to the file.
      fs->Write( info, 0, info->Length );
   }
   finally
   {
      if ( fs )
            delete (IDisposable^)fs;
   }

   // Open the stream and read it back.
   fs = File::Open( path, FileMode::Open );
   try
   {
      array<Byte>^b = gcnew array<Byte>(1024);
      UTF8Encoding^ temp = gcnew UTF8Encoding( true );
      while ( fs->Read( b, 0, b->Length ) > 0 )
      {
         Console::WriteLine( temp->GetString( b ) );
      }
   }
   finally
   {
      if ( fs )
            delete (IDisposable^)fs;
   }
}

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

class Test
{
    public static void Main()
    {
        // Create a temporary file, and put some data into it.
        string path = Path.GetTempFileName();
        using (FileStream fs = File.Open(path, FileMode.Open, FileAccess.Write, FileShare.None))
        {
            Byte[] info = new UTF8Encoding(true).GetBytes("This is some text in the file.");
            // Add some information to the file.
            fs.Write(info, 0, info.Length);
        }

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

            while (fs.Read(b,0,b.Length) > 0)
            {
                Console.WriteLine(temp.GetString(b));
            }
        }
    }
}

open System.IO
open System.Text

// Create a temporary file, and put some data into it.
let path = Path.GetTempFileName()

do
    use fs =
        File.Open(path, FileMode.Open, FileAccess.Write, FileShare.None)

    let info =
        UTF8Encoding(true)
            .GetBytes "This is some text in the file."
    // Add some information to the file.
    fs.Write(info, 0, info.Length)

// Open the stream and read it back.
do
    use fs = File.Open(path, FileMode.Open)
    let b = Array.zeroCreate 1024
    let temp = UTF8Encoding true

    while fs.Read(b, 0, b.Length) > 0 do
        printfn $"{temp.GetString b}"

Imports System.IO
Imports System.Text

Public Class Test
  Public Shared Sub Main()
  
    ' Create a temporary file, and put some data into it. 
    Dim path1 As String = Path.GetTempFileName()
    Using fs As FileStream = File.Open(path1, FileMode.Open, FileAccess.Write, FileShare.None)
      Dim info As Byte() = New UTF8Encoding(True).GetBytes("This is some text in the file.")
      ' Add some information to the file.
      fs.Write(info, 0, info.Length)
    End Using

    ' Open the stream and read it back. 
    Using fs As FileStream = File.Open(path1, FileMode.Open)
      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
    End Using

  End Sub
End Class

備註

允許 path 參數指定相對或絕對路徑資訊。相對路徑資訊會解譯為相對於目前工作目錄。若要取得目前的工作目錄，請參閱 GetCurrentDirectory。

如需一般 I/O 工作的清單，請參閱一般 I/O 工作。

另請參閱

適用於

Open(String, FileStreamOptions)

來源:: File.cs

來源:: File.cs

來源:: File.cs

使用指定的路徑、建立模式、讀取/寫入和共用許可權，初始化類別的新實例 FileStream ，其他 FileStreams 可以擁有相同的檔案、緩衝區大小、其他檔案選項和配置大小。

public:
 static System::IO::FileStream ^ Open(System::String ^ path, System::IO::FileStreamOptions ^ options);

public static System.IO.FileStream Open (string path, System.IO.FileStreamOptions options);

static member Open : string * System.IO.FileStreamOptions -> System.IO.FileStream

Public Shared Function Open (path As String, options As FileStreamOptions) As FileStream

參數

path: String

要開啟之檔案的路徑。

options: FileStreamOptions

物件，描述要使用的選擇性 FileStream 參數。

傳回

FileStream

FileStream包裝已開啟檔案的實例。

備註

FileStream(String, FileStreamOptions) 有關例外狀況的資訊。

適用於

Open(String, FileMode, FileAccess)

來源:: File.cs

來源:: File.cs

來源:: File.cs

在指定路徑上開啟具有指定模式和存取權且不共用的 FileStream。

public:
 static System::IO::FileStream ^ Open(System::String ^ path, System::IO::FileMode mode, System::IO::FileAccess access);

public static System.IO.FileStream Open (string path, System.IO.FileMode mode, System.IO.FileAccess access);

static member Open : string * System.IO.FileMode * System.IO.FileAccess -> System.IO.FileStream

Public Shared Function Open (path As String, mode As FileMode, access As FileAccess) As FileStream

參數

path: String

要開啟的檔案。

mode: FileMode

FileMode 值，指定是否要建立檔案 (如果不存在的話)，以及決定要保留或覆寫現有檔案的內容。

access: FileAccess

FileAccess 值，指定可以在檔案上執行的作業。

傳回

FileStream

不共用的 FileStream，提供對指定檔案 (具有指定模式和存取) 的存取。

例外狀況

ArgumentException

-或-

access 指定了 Read，而 mode 指定了 Create、CreateNew、Truncate 或 Append。

ArgumentNullException

path 為 null。

PathTooLongException

指定的路徑、檔案名稱，或兩者都超出系統定義的長度上限。

DirectoryNotFoundException

指定的路徑無效 (例如，它位於未對應的磁碟機上)。

IOException

開啟檔案時發生 I/O 錯誤。

UnauthorizedAccessException

path 指定了唯讀檔案，而 access 不是 Read。

-或-

path 指定了目錄。

-或-

呼叫端沒有必要的權限。

-或-

mode 是 Create，且指定的檔案是隱藏檔案。

ArgumentOutOfRangeException

mode 或 access 指定了無效的值。

FileNotFoundException

找不到 path 指定的檔案。

NotSupportedException

path 格式無效。

範例

下列範例會開啟具有唯讀存取權的檔案。


using namespace System;
using namespace System::IO;
using namespace System::Text;

int main()
{
    // This sample assumes that you have a folder named "c:\temp" on your computer.
    String^ filePath = "c:\\temp\\MyTest.txt";
    // Delete the file if it exists.
    if (File::Exists( filePath ))
    {
        File::Delete( filePath );
    }
    // Create the file.
    FileStream^ fs = File::Create( filePath );
    try
    {
        array<Byte>^ info = ( gcnew UTF8Encoding( true ))->GetBytes( "This is some text in the file." );
        
        // Add some information to the file.
        fs->Write( info, 0, info->Length );
    }
    finally
    {
        if ( fs )
            delete (IDisposable^)fs;
    }

    // Open the stream and read it back.
    fs = File::Open( filePath, FileMode::Open, FileAccess::Read );
    try
    {
        array<Byte>^ b = gcnew array<Byte>(1024);
        UTF8Encoding^ temp = gcnew UTF8Encoding( true );
        while ( fs->Read( b, 0, b->Length ) > 0 )
        {
            Console::WriteLine( temp->GetString( b ) );
        }
        try
        {
            // Try to write to the file.
            fs->Write( b, 0, b->Length );
        }
        catch ( Exception^ e ) 
        {
            Console::WriteLine( "Writing was disallowed, as expected: {0}", e->ToString() );
        }
    }
    finally
    {
        if ( fs )
            delete (IDisposable^)fs;
    }
}

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

class Test
{
    public static void Main()
    {
        // This sample assumes that you have a folder named "c:\temp" on your computer.
        string filePath = @"c:\temp\MyTest.txt";

        // Delete the file if it exists.
        if (File.Exists(filePath))
        {
            File.Delete(filePath);
        }

        // Create the file.
        using (FileStream fs = File.Create(filePath))
        {
            Byte[] info = new UTF8Encoding(true).GetBytes("This is some text in the file.");
            // Add some information to the file.
            fs.Write(info, 0, info.Length);
        }

        // Open the stream and read it back.
        using (FileStream fs = File.Open(filePath, FileMode.Open, FileAccess.Read))
        {
            byte[] b = new byte[1024];
            UTF8Encoding temp = new UTF8Encoding(true);

            while (fs.Read(b,0,b.Length) > 0)
            {
                Console.WriteLine(temp.GetString(b));
            }

            try
            {
                // Try to write to the file.
                fs.Write(b,0,b.Length);
            }
            catch (Exception e)
            {
                Console.WriteLine("Writing was disallowed, as expected: {0}", e.ToString());
            }
        }
    }
}

open System.IO
open System.Text

// This sample assumes that you have a folder named "c:\temp" on your computer.
let filePath = @"c:\temp\MyTest.txt"

// Delete the file if it exists.
if File.Exists filePath then
    File.Delete filePath

// Create the file.
do
    use fs = File.Create filePath

    let info =
        UTF8Encoding(true)
            .GetBytes "This is some text in the file."
    // Add some information to the file.
    fs.Write(info, 0, info.Length)

// Open the stream and read it back.
do
    use fs =
        File.Open(filePath, FileMode.Open, FileAccess.Read)

    let b = Array.zeroCreate 1024
    let temp = UTF8Encoding true

    while fs.Read(b, 0, b.Length) > 0 do
        printfn $"{temp.GetString b}"

    try
        // Try to write to the file.
        fs.Write(b, 0, b.Length)
    with
    | e -> printfn $"Writing was disallowed, as expected: {e}"

Imports System.IO
Imports System.Text

Public Class Test
  Public Shared Sub Main()
    ' This sample assumes that you have a folder named "c:\temp" on your computer. 
    Dim filePath As String = "c:\temp\MyTest.txt"

    ' Delete the file if it exists. 
    If File.Exists(filePath) Then
      File.Delete(filePath)
    End If

    ' Create the file.
    Using fs As FileStream = File.Create(filePath)
      Dim info As Byte() = New UTF8Encoding(True).GetBytes("This is some text in the file.")

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

    ' Open the stream and read it back.
    Using fs As FileStream = File.Open(filePath, FileMode.Open, FileAccess.Read)
      Dim b(1023) As Byte
      Dim temp As UTF8Encoding = New UTF8Encoding(True)

      ' Display the information on the console. 
      Do While fs.Read(b, 0, b.Length) > 0
        Console.WriteLine(temp.GetString(b))
      Loop

      Try
        ' Try to write to the file
        fs.Write(b, 0, b.Length)
      Catch e As Exception
        Console.WriteLine("Writing was disallowed, as expected: " & e.ToString())
      End Try

    End Using

  End Sub
End Class

備註

允許 path 參數指定相對或絕對路徑資訊。相對路徑資訊會解譯為相對於目前工作目錄。若要取得目前的工作目錄，請參閱 GetCurrentDirectory。

另請參閱

適用於

共用方式為

File.Open 方法

定義

多載

Open(String, FileMode, FileAccess, FileShare)

參數

傳回

例外狀況

範例

備註

另請參閱

適用於

Open(String, FileMode)

參數

傳回

例外狀況

範例

備註

另請參閱

適用於

Open(String, FileStreamOptions)

參數

傳回

備註

適用於

Open(String, FileMode, FileAccess)

參數

傳回

例外狀況

範例

備註

另請參閱

適用於

其他資源