StreamReader 构造函数

参考

定义

命名空间:: System.IO

程序集:: System.IO.dll

程序集:: System.Runtime.dll

程序集:: System.Runtime.Extensions.dll

程序集:: mscorlib.dll

程序集:: netstandard.dll

重要

一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。

为指定的流初始化 StreamReader 类的新实例。

重载

StreamReader(Stream)	为指定的流初始化 StreamReader 类的新实例。
StreamReader(Stream, Encoding, Boolean, Int32, Boolean)	为指定的流初始化 StreamReader 类的新实例，带有指定的字符编码、字节顺序标记检测选项和缓冲区大小，有选择性的打开流。
StreamReader(String, Encoding, Boolean, FileStreamOptions)	使用指定的字符编码、字节顺序标记检测选项并为指定的对象配置FileStreamOptions指定文件路径初始化类的新实例StreamReader。
StreamReader(String, Encoding, Boolean, Int32)	为指定的文件名初始化 StreamReader 类的新实例，带有指定字符编码、字节顺序标记检测选项和缓冲区大小。
StreamReader(Stream, Encoding, Boolean, Int32)	为指定的流初始化 StreamReader 类的新实例，带有指定的字符编码、字节顺序标记检测选项和缓冲区大小。
StreamReader(Stream, Encoding, Boolean)	为指定的流初始化 StreamReader 类的新实例，带有指定的字符编码和字节顺序标记检测选项。
StreamReader(String, Encoding, Boolean)	为指定的文件名初始化 StreamReader 类的新实例，带有指定的字符编码和字节顺序标记检测选项。
StreamReader(String, FileStreamOptions)	使用默认编码为指定文件路径初始化类的新实例 StreamReader ，启用文件开头的字节顺序标记检测，并使用指定的 FileStreamOptions 对象进行配置。
StreamReader(String, Boolean)	为指定的文件名初始化 StreamReader 类的新实例，带有指定的字节顺序标记检测选项。
StreamReader(Stream, Encoding)	用指定的字符编码为指定的流初始化 StreamReader 类的一个新实例。
StreamReader(Stream, Boolean)	用指定的字节顺序标记检测选项，为指定的流初始化 StreamReader 类的一个新实例。
StreamReader(String)	为指定的文件名初始化 StreamReader 类的新实例。
StreamReader(String, Encoding)	用指定的字符编码，为指定的文件名初始化 StreamReader 类的一个新实例。

StreamReader(Stream)

Source:: StreamReader.cs

Source:: StreamReader.cs

Source:: StreamReader.cs

为指定的流初始化 StreamReader 类的新实例。

public:
 StreamReader(System::IO::Stream ^ stream);

public StreamReader (System.IO.Stream stream);

new System.IO.StreamReader : System.IO.Stream -> System.IO.StreamReader

Public Sub New (stream As Stream)

参数

stream: Stream

要读取的流。

例外

ArgumentException

stream 不支持读取。

ArgumentNullException

stream 为 null。

示例

下面的代码示例演示了此 StreamReader 构造函数。

using namespace System;
using namespace System::IO;
int main()
{
   String^ path = "c:\\temp\\MyTest.txt";
   try
   {
      if ( File::Exists( path ) )
      {
         File::Delete( path );
      }
      StreamWriter^ sw = gcnew StreamWriter( path );
      try
      {
         sw->WriteLine( "This" );
         sw->WriteLine( "is some text" );
         sw->WriteLine( "to test" );
         sw->WriteLine( "Reading" );
      }
      finally
      {
         delete sw;
      }

      FileStream^ fs = gcnew FileStream( path,FileMode::Open );
      try
      {
         StreamReader^ sr = gcnew StreamReader( fs );
         try
         {
            while ( sr->Peek() >= 0 )
            {
               Console::WriteLine( sr->ReadLine() );
            }
         }
         finally
         {
            delete sr;
         }
      }
      finally
      {
         delete fs;
      }
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "The process failed: {0}", e );
   }
}

using System;
using System.IO;

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

        try
        {
            if (File.Exists(path))
            {
                File.Delete(path);
            }

            using (StreamWriter sw = new StreamWriter(new FileStream(path, FileMode.CreateNew)))
            {
                sw.WriteLine("This");
                sw.WriteLine("is some text");
                sw.WriteLine("to test");
                sw.WriteLine("reading");
            }

            using (StreamReader sr = new StreamReader(new FileStream(path, FileMode.Open)))
            {
                while (sr.Peek() >= 0)
                {
                    Console.WriteLine(sr.ReadLine());
                }
            }
        }
        catch (Exception e)
        {
            Console.WriteLine("The process failed: {0}", e.ToString());
        }
    }
}

Imports System.IO

Public Class Test

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

        Try
            If File.Exists(path) Then
                File.Delete(path)
            End If

            Dim sw As StreamWriter = New StreamWriter(path)
            sw.WriteLine("This")
            sw.WriteLine("is some text")
            sw.WriteLine("to test")
            sw.WriteLine("Reading")
            sw.Close()

            Dim fs As FileStream = New FileStream(path, FileMode.Open)

            Dim sr As StreamReader = New StreamReader(fs)

            Do While sr.Peek() >= 0
                Console.WriteLine(sr.ReadLine())
            Loop
            sr.Close()
            fs.Close()
        Catch e As Exception
            Console.WriteLine("The process failed: {0}", e.ToString())
        End Try
    End Sub
End Class

注解

此构造函数使用参数将编码初始化为 UTF8Encoding、 BaseStream 属性 stream ，并将内部缓冲区大小初始化为 1024 字节。

调用时StreamReader.Dispose，对象StreamReader Dispose()对提供Stream的对象调用。

注意

编译具有特定区域性设置的一组字符并检索具有不同区域性设置的相同字符时，这些字符可能无法解释，并可能导致引发异常。

有关常见 I/O 任务的列表，请参阅常见 I/O 任务。

另请参阅

适用于

StreamReader(Stream, Encoding, Boolean, Int32, Boolean)

Source:: StreamReader.cs

Source:: StreamReader.cs

Source:: StreamReader.cs

为指定的流初始化 StreamReader 类的新实例，带有指定的字符编码、字节顺序标记检测选项和缓冲区大小，有选择性的打开流。

public:
 StreamReader(System::IO::Stream ^ stream, System::Text::Encoding ^ encoding, bool detectEncodingFromByteOrderMarks, int bufferSize, bool leaveOpen);

public StreamReader (System.IO.Stream stream, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize, bool leaveOpen);

public StreamReader (System.IO.Stream stream, System.Text.Encoding? encoding = default, bool detectEncodingFromByteOrderMarks = true, int bufferSize = -1, bool leaveOpen = false);

new System.IO.StreamReader : System.IO.Stream * System.Text.Encoding * bool * int * bool -> System.IO.StreamReader

Public Sub New (stream As Stream, encoding As Encoding, detectEncodingFromByteOrderMarks As Boolean, bufferSize As Integer, leaveOpen As Boolean)

Public Sub New (stream As Stream, Optional encoding As Encoding = Nothing, Optional detectEncodingFromByteOrderMarks As Boolean = true, Optional bufferSize As Integer = -1, Optional leaveOpen As Boolean = false)

参数

stream: Stream

要读取的流。

encoding: Encoding

要使用的字符编码。

detectEncodingFromByteOrderMarks: Boolean

如果要在文件开头查找字节顺序标记，则为true ；否则为 false。

bufferSize: Int32

最小缓冲区大小。

leaveOpen: Boolean

如果在释放 StreamReader 对象后保持流处于打开状态，则为 true；否则为 false。

注解

除非您设置leaveOpen参数true，则StreamReader对象调用Dispose()上提供Stream对象时StreamReader.Dispose调用。

缓冲区大小（以 16 位字符数为单位）由 bufferSize 参数设置。如果 bufferSize 小于允许的最小大小 (128 个字符) ，则使用允许的最小大小。

此构造函数使你能够在首次从 StreamReader 对象读取时更改编码。 detectEncodingFromByteOrderMarks如果参数为 true，则构造函数通过查看流的前四个字节来检测编码。如果文件以适当的字节顺序标记开头，它会自动识别 UTF-8、little-endian UTF-16、big-endian UTF-16、little-endian UTF-32 和 big-endian UTF-32 文本。否则，将使用用户提供的编码。有关更多信息，请参阅 Encoding.GetPreamble 方法。

注意

从 Stream读取时，使用与流内部缓冲区大小相同的缓冲区更高效。

注意

编译具有特定区域性设置的一组字符并检索具有不同区域性设置的相同字符时，这些字符可能无法正确解释，并可能导致引发异常。

适用于

StreamReader(String, Encoding, Boolean, FileStreamOptions)

Source:: StreamReader.cs

Source:: StreamReader.cs

Source:: StreamReader.cs

使用指定的字符编码、字节顺序标记检测选项并为指定的对象配置FileStreamOptions指定文件路径初始化类的新实例StreamReader。

public:
 StreamReader(System::String ^ path, System::Text::Encoding ^ encoding, bool detectEncodingFromByteOrderMarks, System::IO::FileStreamOptions ^ options);

public StreamReader (string path, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks, System.IO.FileStreamOptions options);

new System.IO.StreamReader : string * System.Text.Encoding * bool * System.IO.FileStreamOptions -> System.IO.StreamReader

Public Sub New (path As String, encoding As Encoding, detectEncodingFromByteOrderMarks As Boolean, options As FileStreamOptions)

参数

path: String

要读取的完整文件路径。

encoding: Encoding

要使用的字符编码。

detectEncodingFromByteOrderMarks: Boolean

指示是否在文件头查找字节顺序标记。

options: FileStreamOptions

一个对象，该对象指定基础 FileStream的配置选项。

例外

ArgumentException

stream 不可读。

      -or-

path 为空字符串 ("")。

ArgumentNullException

path、encoding 或 options 为 null。

FileNotFoundException

找不到该文件。

DirectoryNotFoundException

指定的路径无效，例如位于未映射的驱动器上。

NotSupportedException

path 包含不正确或无效的文件名、目录名或卷标语法。

另请参阅

适用于

StreamReader(String, Encoding, Boolean, Int32)

Source:: StreamReader.cs

Source:: StreamReader.cs

Source:: StreamReader.cs

为指定的文件名初始化 StreamReader 类的新实例，带有指定字符编码、字节顺序标记检测选项和缓冲区大小。

public:
 StreamReader(System::String ^ path, System::Text::Encoding ^ encoding, bool detectEncodingFromByteOrderMarks, int bufferSize);

public StreamReader (string path, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize);

new System.IO.StreamReader : string * System.Text.Encoding * bool * int -> System.IO.StreamReader

Public Sub New (path As String, encoding As Encoding, detectEncodingFromByteOrderMarks As Boolean, bufferSize As Integer)

参数

path: String

要读取的完整文件路径。

encoding: Encoding

要使用的字符编码。

detectEncodingFromByteOrderMarks: Boolean

指示是否在文件头查找字节顺序标记。

bufferSize: Int32

最小缓冲区大小（以 16 位字符的数目为单位）。

例外

ArgumentException

path 为空字符串 ("")。

ArgumentNullException

path 或 encoding 为 null。

FileNotFoundException

找不到该文件。

DirectoryNotFoundException

指定的路径无效，例如位于未映射的驱动器上。

NotSupportedException

path 包含不正确或无效的文件名、目录名或卷标语法。

ArgumentOutOfRangeException

buffersize 小于或等于零。

示例

下面的代码示例演示了此 StreamReader 构造函数。

void getNewStreamReader()
{
   
   //Get a new StreamReader in ASCII format from a
   //file using a buffer and byte order mark detection
   StreamReader^ srAsciiFromFileFalse512 = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //file with byte order mark detection = false
   StreamReader^ srAsciiFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a file 
   StreamReader^ srAsciiFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //file with byte order mark detection = false
   StreamReader^ srFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",false );
   
   //Get a new StreamReader from a file
   StreamReader^ srFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt" );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false and a buffer
   StreamReader^ srAsciiFromStreamFalse512 = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false
   StreamReader^ srAsciiFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a FileStream
   StreamReader^ srAsciiFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //FileStream with byte order mark detection = false
   StreamReader^ srFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),false );
   
   //Get a new StreamReader from a FileStream
   StreamReader^ srFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ) );
}

private void getNewStreamReader()
{
    //Get a new StreamReader in ASCII format from a
    //file using a buffer and byte order mark detection
    StreamReader srAsciiFromFileFalse512 =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //file with byte order mark detection = false
    StreamReader srAsciiFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a file
    StreamReader srAsciiFromFile =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //file with byte order mark detection = false
    StreamReader srFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt", false);
    //Get a new StreamReader from a file
    StreamReader srFromFile =
        new StreamReader("C:\\Temp\\Test.txt");
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false and a buffer
    StreamReader srAsciiFromStreamFalse512 = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false
    StreamReader srAsciiFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a FileStream
    StreamReader srAsciiFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //FileStream with byte order mark detection = false
    StreamReader srFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        false);
    //Get a new StreamReader from a FileStream
    StreamReader srFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"));
}

Private Sub getNewStreamReader()
    Dim S As Stream = File.OpenRead("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'file using a buffer and byte order mark detection
    Dim SrAsciiFromFileFalse512 As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'file with byte order mark detection = false
    Dim SrAsciiFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a file 
    Dim SrAsciiFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'file with byte order mark detection = false        
    Dim SrFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", False)
    'Get a new StreamReader from a file
    Dim SrFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false and a buffer
    Dim SrAsciiFromStreamFalse512 As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false
    Dim SrAsciiFromStreamFalse = New StreamReader(S, _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a FileStream
    Dim SrAsciiFromStream As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'FileStream with byte order mark detection = false
    Dim SrFromStreamFalse As StreamReader = New StreamReader(S, False)
    'Get a new StreamReader from a FileStream
    Dim SrFromStream As StreamReader = New StreamReader(S)

End Sub

注解

此构造函数初始化参数 encoding 指定的编码。

此构造函数允许你在首次从 StreamReader 对象读取时更改编码。参数 detectEncodingFromByteOrderMarks 通过查看流的前四个字节来检测编码。如果文件以适当的字节顺序标记开头，它会自动识别 UTF-8、little-endian UTF-16、big-endian UTF-16、little-endian UTF-32 和 big-endian UTF-32 文本。否则，将使用用户提供的编码。有关更多信息，请参阅 Encoding.GetPreamble 方法。

缓冲区大小（以 16 位字符数为单位）由 bufferSize 参数设置。如果 bufferSize 小于允许的最小大小 (128 个字符) ，则使用允许的最小大小。

参数 path 可以是文件名，包括通用命名约定 (UNC) 共享上的文件。

参数 path 不一定是存储在磁盘上的文件;它可以是支持使用流进行访问的系统的任何部分。

注意

编译具有特定区域性设置的一组字符并检索具有不同区域性设置的相同字符时，这些字符可能无法解释，并可能导致引发异常。

有关常见 I/O 任务的列表，请参阅常见 I/O 任务。

另请参阅

适用于

StreamReader(Stream, Encoding, Boolean, Int32)

Source:: StreamReader.cs

Source:: StreamReader.cs

Source:: StreamReader.cs

为指定的流初始化 StreamReader 类的新实例，带有指定的字符编码、字节顺序标记检测选项和缓冲区大小。

public:
 StreamReader(System::IO::Stream ^ stream, System::Text::Encoding ^ encoding, bool detectEncodingFromByteOrderMarks, int bufferSize);

public StreamReader (System.IO.Stream stream, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize);

new System.IO.StreamReader : System.IO.Stream * System.Text.Encoding * bool * int -> System.IO.StreamReader

Public Sub New (stream As Stream, encoding As Encoding, detectEncodingFromByteOrderMarks As Boolean, bufferSize As Integer)

参数

stream: Stream

要读取的流。

encoding: Encoding

要使用的字符编码。

detectEncodingFromByteOrderMarks: Boolean

指示是否在文件头查找字节顺序标记。

bufferSize: Int32

最小缓冲区大小。

例外

ArgumentException

流不支持读取。

ArgumentNullException

stream 或 encoding 为 null。

ArgumentOutOfRangeException

bufferSize 小于或等于零。

示例

下面的代码示例演示了此 StreamReader 构造函数。

void getNewStreamReader()
{
   
   //Get a new StreamReader in ASCII format from a
   //file using a buffer and byte order mark detection
   StreamReader^ srAsciiFromFileFalse512 = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //file with byte order mark detection = false
   StreamReader^ srAsciiFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a file 
   StreamReader^ srAsciiFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //file with byte order mark detection = false
   StreamReader^ srFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",false );
   
   //Get a new StreamReader from a file
   StreamReader^ srFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt" );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false and a buffer
   StreamReader^ srAsciiFromStreamFalse512 = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false
   StreamReader^ srAsciiFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a FileStream
   StreamReader^ srAsciiFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //FileStream with byte order mark detection = false
   StreamReader^ srFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),false );
   
   //Get a new StreamReader from a FileStream
   StreamReader^ srFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ) );
}

private void getNewStreamReader()
{
    //Get a new StreamReader in ASCII format from a
    //file using a buffer and byte order mark detection
    StreamReader srAsciiFromFileFalse512 =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //file with byte order mark detection = false
    StreamReader srAsciiFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a file
    StreamReader srAsciiFromFile =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //file with byte order mark detection = false
    StreamReader srFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt", false);
    //Get a new StreamReader from a file
    StreamReader srFromFile =
        new StreamReader("C:\\Temp\\Test.txt");
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false and a buffer
    StreamReader srAsciiFromStreamFalse512 = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false
    StreamReader srAsciiFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a FileStream
    StreamReader srAsciiFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //FileStream with byte order mark detection = false
    StreamReader srFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        false);
    //Get a new StreamReader from a FileStream
    StreamReader srFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"));
}

Private Sub getNewStreamReader()
    Dim S As Stream = File.OpenRead("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'file using a buffer and byte order mark detection
    Dim SrAsciiFromFileFalse512 As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'file with byte order mark detection = false
    Dim SrAsciiFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a file 
    Dim SrAsciiFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'file with byte order mark detection = false        
    Dim SrFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", False)
    'Get a new StreamReader from a file
    Dim SrFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false and a buffer
    Dim SrAsciiFromStreamFalse512 As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false
    Dim SrAsciiFromStreamFalse = New StreamReader(S, _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a FileStream
    Dim SrAsciiFromStream As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'FileStream with byte order mark detection = false
    Dim SrFromStreamFalse As StreamReader = New StreamReader(S, False)
    'Get a new StreamReader from a FileStream
    Dim SrFromStream As StreamReader = New StreamReader(S)

End Sub

注解

缓冲区大小（以 16 位字符数为单位）由 bufferSize 参数设置。如果 bufferSize 小于允许的最小大小 (128 个字符) ，则使用允许的最小大小。

调用时StreamReader.Dispose，对象StreamReader Dispose()对提供Stream的对象调用。

注意

从 Stream读取时，使用与流内部缓冲区大小相同的缓冲区更高效。

注意

编译具有特定区域性设置的一组字符并检索具有不同区域性设置的相同字符时，这些字符可能无法解释，并可能导致引发异常。

有关常见 I/O 任务的列表，请参阅常见 I/O 任务。

另请参阅

适用于

StreamReader(Stream, Encoding, Boolean)

Source:: StreamReader.cs

Source:: StreamReader.cs

Source:: StreamReader.cs

为指定的流初始化 StreamReader 类的新实例，带有指定的字符编码和字节顺序标记检测选项。

public:
 StreamReader(System::IO::Stream ^ stream, System::Text::Encoding ^ encoding, bool detectEncodingFromByteOrderMarks);

public StreamReader (System.IO.Stream stream, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks);

new System.IO.StreamReader : System.IO.Stream * System.Text.Encoding * bool -> System.IO.StreamReader

Public Sub New (stream As Stream, encoding As Encoding, detectEncodingFromByteOrderMarks As Boolean)

参数

stream: Stream

要读取的流。

encoding: Encoding

要使用的字符编码。

detectEncodingFromByteOrderMarks: Boolean

指示是否在文件头查找字节顺序标记。

例外

ArgumentException

stream 不支持读取。

ArgumentNullException

stream 或 encoding 为 null。

示例

下面的代码示例演示了此 StreamReader 构造函数。

void getNewStreamReader()
{
   
   //Get a new StreamReader in ASCII format from a
   //file using a buffer and byte order mark detection
   StreamReader^ srAsciiFromFileFalse512 = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //file with byte order mark detection = false
   StreamReader^ srAsciiFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a file 
   StreamReader^ srAsciiFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //file with byte order mark detection = false
   StreamReader^ srFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",false );
   
   //Get a new StreamReader from a file
   StreamReader^ srFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt" );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false and a buffer
   StreamReader^ srAsciiFromStreamFalse512 = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false
   StreamReader^ srAsciiFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a FileStream
   StreamReader^ srAsciiFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //FileStream with byte order mark detection = false
   StreamReader^ srFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),false );
   
   //Get a new StreamReader from a FileStream
   StreamReader^ srFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ) );
}

private void getNewStreamReader()
{
    //Get a new StreamReader in ASCII format from a
    //file using a buffer and byte order mark detection
    StreamReader srAsciiFromFileFalse512 =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //file with byte order mark detection = false
    StreamReader srAsciiFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a file
    StreamReader srAsciiFromFile =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //file with byte order mark detection = false
    StreamReader srFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt", false);
    //Get a new StreamReader from a file
    StreamReader srFromFile =
        new StreamReader("C:\\Temp\\Test.txt");
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false and a buffer
    StreamReader srAsciiFromStreamFalse512 = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false
    StreamReader srAsciiFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a FileStream
    StreamReader srAsciiFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //FileStream with byte order mark detection = false
    StreamReader srFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        false);
    //Get a new StreamReader from a FileStream
    StreamReader srFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"));
}

Private Sub getNewStreamReader()
    Dim S As Stream = File.OpenRead("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'file using a buffer and byte order mark detection
    Dim SrAsciiFromFileFalse512 As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'file with byte order mark detection = false
    Dim SrAsciiFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a file 
    Dim SrAsciiFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'file with byte order mark detection = false        
    Dim SrFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", False)
    'Get a new StreamReader from a file
    Dim SrFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false and a buffer
    Dim SrAsciiFromStreamFalse512 As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false
    Dim SrAsciiFromStreamFalse = New StreamReader(S, _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a FileStream
    Dim SrAsciiFromStream As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'FileStream with byte order mark detection = false
    Dim SrFromStreamFalse As StreamReader = New StreamReader(S, False)
    'Get a new StreamReader from a FileStream
    Dim SrFromStream As StreamReader = New StreamReader(S)

End Sub

注解

此构造函数将参数指定的 encoding 编码、 BaseStream 使用 stream 参数的属性以及内部缓冲区大小初始化为 1024 字节。

参数 detectEncodingFromByteOrderMarks 通过查看流的前四个字节来检测编码。如果文件以适当的字节顺序标记开头，它会自动识别 UTF-8、little-endian UTF-16、big-endian UTF-16、little-endian UTF-32 和 big-endian UTF-32 文本。否则，将使用用户提供的编码。有关更多信息，请参阅 Encoding.GetPreamble 方法。

调用时StreamReader.Dispose，对象StreamReader Dispose()对提供Stream的对象调用。

注意

编译具有特定区域性设置的一组字符并检索具有不同区域性设置的相同字符时，这些字符可能无法解释，并可能导致引发异常。

有关常见 I/O 任务的列表，请参阅常见 I/O 任务。

另请参阅

适用于

StreamReader(String, Encoding, Boolean)

Source:: StreamReader.cs

Source:: StreamReader.cs

Source:: StreamReader.cs

为指定的文件名初始化 StreamReader 类的新实例，带有指定的字符编码和字节顺序标记检测选项。

public:
 StreamReader(System::String ^ path, System::Text::Encoding ^ encoding, bool detectEncodingFromByteOrderMarks);

public StreamReader (string path, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks);

new System.IO.StreamReader : string * System.Text.Encoding * bool -> System.IO.StreamReader

Public Sub New (path As String, encoding As Encoding, detectEncodingFromByteOrderMarks As Boolean)

参数

path: String

要读取的完整文件路径。

encoding: Encoding

要使用的字符编码。

detectEncodingFromByteOrderMarks: Boolean

指示是否在文件头查找字节顺序标记。

例外

ArgumentException

path 为空字符串 ("")。

ArgumentNullException

path 或 encoding 为 null。

FileNotFoundException

找不到该文件。

DirectoryNotFoundException

指定的路径无效，例如位于未映射的驱动器上。

NotSupportedException

path 包含不正确或无效的文件名、目录名或卷标语法。

示例

下面的代码示例演示了此 StreamReader 构造函数。

void getNewStreamReader()
{
   
   //Get a new StreamReader in ASCII format from a
   //file using a buffer and byte order mark detection
   StreamReader^ srAsciiFromFileFalse512 = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //file with byte order mark detection = false
   StreamReader^ srAsciiFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a file 
   StreamReader^ srAsciiFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //file with byte order mark detection = false
   StreamReader^ srFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",false );
   
   //Get a new StreamReader from a file
   StreamReader^ srFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt" );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false and a buffer
   StreamReader^ srAsciiFromStreamFalse512 = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false
   StreamReader^ srAsciiFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a FileStream
   StreamReader^ srAsciiFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //FileStream with byte order mark detection = false
   StreamReader^ srFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),false );
   
   //Get a new StreamReader from a FileStream
   StreamReader^ srFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ) );
}

private void getNewStreamReader()
{
    //Get a new StreamReader in ASCII format from a
    //file using a buffer and byte order mark detection
    StreamReader srAsciiFromFileFalse512 =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //file with byte order mark detection = false
    StreamReader srAsciiFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a file
    StreamReader srAsciiFromFile =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //file with byte order mark detection = false
    StreamReader srFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt", false);
    //Get a new StreamReader from a file
    StreamReader srFromFile =
        new StreamReader("C:\\Temp\\Test.txt");
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false and a buffer
    StreamReader srAsciiFromStreamFalse512 = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false
    StreamReader srAsciiFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a FileStream
    StreamReader srAsciiFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //FileStream with byte order mark detection = false
    StreamReader srFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        false);
    //Get a new StreamReader from a FileStream
    StreamReader srFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"));
}

Private Sub getNewStreamReader()
    Dim S As Stream = File.OpenRead("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'file using a buffer and byte order mark detection
    Dim SrAsciiFromFileFalse512 As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'file with byte order mark detection = false
    Dim SrAsciiFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a file 
    Dim SrAsciiFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'file with byte order mark detection = false        
    Dim SrFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", False)
    'Get a new StreamReader from a file
    Dim SrFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false and a buffer
    Dim SrAsciiFromStreamFalse512 As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false
    Dim SrAsciiFromStreamFalse = New StreamReader(S, _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a FileStream
    Dim SrAsciiFromStream As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'FileStream with byte order mark detection = false
    Dim SrFromStreamFalse As StreamReader = New StreamReader(S, False)
    'Get a new StreamReader from a FileStream
    Dim SrFromStream As StreamReader = New StreamReader(S)

End Sub

注解

此构造函数初始化参数 encoding 指定的编码，并将内部缓冲区大小初始化为 1024 字节。

参数 path 可以是文件名，包括通用命名约定 (UNC) 共享上的文件。

参数 path 不一定是存储在磁盘上的文件;它可以是支持使用流进行访问的系统的任何部分。

注意

编译具有特定区域性设置的一组字符并检索具有不同区域性设置的相同字符时，这些字符可能无法解释，并可能导致引发异常。

有关常见 I/O 任务的列表，请参阅常见 I/O 任务。

另请参阅

适用于

StreamReader(String, FileStreamOptions)

Source:: StreamReader.cs

Source:: StreamReader.cs

Source:: StreamReader.cs

使用默认编码为指定文件路径初始化类的新实例 StreamReader ，启用文件开头的字节顺序标记检测，并使用指定的 FileStreamOptions 对象进行配置。

public:
 StreamReader(System::String ^ path, System::IO::FileStreamOptions ^ options);

public StreamReader (string path, System.IO.FileStreamOptions options);

new System.IO.StreamReader : string * System.IO.FileStreamOptions -> System.IO.StreamReader

Public Sub New (path As String, options As FileStreamOptions)

参数

path: String

要读取的完整文件路径。

options: FileStreamOptions

一个对象，该对象指定基础 FileStream的配置选项。

例外

ArgumentException

stream 不可读。

- 或 -

      <code data-dev-comment-type="paramref">path</code> is an empty string ("").

ArgumentNullException

path 或 options 为 null。

FileNotFoundException

找不到该文件。

DirectoryNotFoundException

指定的路径无效，例如位于未映射的驱动器上。

IOException

path 包含不正确或无效的文件名、目录名或卷标语法。

另请参阅

适用于

StreamReader(String, Boolean)

Source:: StreamReader.cs

Source:: StreamReader.cs

Source:: StreamReader.cs

为指定的文件名初始化 StreamReader 类的新实例，带有指定的字节顺序标记检测选项。

public:
 StreamReader(System::String ^ path, bool detectEncodingFromByteOrderMarks);

public StreamReader (string path, bool detectEncodingFromByteOrderMarks);

new System.IO.StreamReader : string * bool -> System.IO.StreamReader

Public Sub New (path As String, detectEncodingFromByteOrderMarks As Boolean)

参数

path: String

要读取的完整文件路径。

detectEncodingFromByteOrderMarks: Boolean

指示是否在文件头查找字节顺序标记。

例外

ArgumentException

path 为空字符串 ("")。

ArgumentNullException

path 为 null。

FileNotFoundException

找不到该文件。

DirectoryNotFoundException

指定的路径无效，例如位于未映射的驱动器上。

IOException

path 包含不正确或无效的文件名、目录名或卷标语法。

示例

下面的代码示例演示了此 StreamReader 构造函数。

void getNewStreamReader()
{
   
   //Get a new StreamReader in ASCII format from a
   //file using a buffer and byte order mark detection
   StreamReader^ srAsciiFromFileFalse512 = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //file with byte order mark detection = false
   StreamReader^ srAsciiFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a file 
   StreamReader^ srAsciiFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //file with byte order mark detection = false
   StreamReader^ srFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",false );
   
   //Get a new StreamReader from a file
   StreamReader^ srFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt" );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false and a buffer
   StreamReader^ srAsciiFromStreamFalse512 = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false
   StreamReader^ srAsciiFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a FileStream
   StreamReader^ srAsciiFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //FileStream with byte order mark detection = false
   StreamReader^ srFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),false );
   
   //Get a new StreamReader from a FileStream
   StreamReader^ srFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ) );
}

private void getNewStreamReader()
{
    //Get a new StreamReader in ASCII format from a
    //file using a buffer and byte order mark detection
    StreamReader srAsciiFromFileFalse512 =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //file with byte order mark detection = false
    StreamReader srAsciiFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a file
    StreamReader srAsciiFromFile =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //file with byte order mark detection = false
    StreamReader srFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt", false);
    //Get a new StreamReader from a file
    StreamReader srFromFile =
        new StreamReader("C:\\Temp\\Test.txt");
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false and a buffer
    StreamReader srAsciiFromStreamFalse512 = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false
    StreamReader srAsciiFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a FileStream
    StreamReader srAsciiFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //FileStream with byte order mark detection = false
    StreamReader srFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        false);
    //Get a new StreamReader from a FileStream
    StreamReader srFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"));
}

Private Sub getNewStreamReader()
    Dim S As Stream = File.OpenRead("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'file using a buffer and byte order mark detection
    Dim SrAsciiFromFileFalse512 As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'file with byte order mark detection = false
    Dim SrAsciiFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a file 
    Dim SrAsciiFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'file with byte order mark detection = false        
    Dim SrFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", False)
    'Get a new StreamReader from a file
    Dim SrFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false and a buffer
    Dim SrAsciiFromStreamFalse512 As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false
    Dim SrAsciiFromStreamFalse = New StreamReader(S, _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a FileStream
    Dim SrAsciiFromStream As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'FileStream with byte order mark detection = false
    Dim SrFromStreamFalse As StreamReader = New StreamReader(S, False)
    'Get a new StreamReader from a FileStream
    Dim SrFromStream As StreamReader = New StreamReader(S)

End Sub

注解

此构造函数使用参数将编码初始化为 UTF8Encoding、 BaseStream 属性 stream ，并将内部缓冲区大小初始化为 1024 字节。

参数 path 可以是文件名，包括通用命名约定 (UNC) 共享上的文件。

参数 path 不一定是存储在磁盘上的文件;它可以是支持使用流进行访问的系统的任何部分。

参数 detectEncodingFromByteOrderMarks 通过查看流的前四个字节来检测编码。如果文件以适当的字节顺序标记开头，它会自动识别 UTF-8、little-endian UTF-16、big-endian UTF-16、little-endian UTF-32 和 big-endian UTF-32 文本。否则， UTF8Encoding 使用。有关更多信息，请参阅 Encoding.GetPreamble 方法。

有关常见 I/O 任务的列表，请参阅常见 I/O 任务。

另请参阅

适用于

StreamReader(Stream, Encoding)

Source:: StreamReader.cs

Source:: StreamReader.cs

Source:: StreamReader.cs

用指定的字符编码为指定的流初始化 StreamReader 类的一个新实例。

public:
 StreamReader(System::IO::Stream ^ stream, System::Text::Encoding ^ encoding);

public StreamReader (System.IO.Stream stream, System.Text.Encoding encoding);

new System.IO.StreamReader : System.IO.Stream * System.Text.Encoding -> System.IO.StreamReader

Public Sub New (stream As Stream, encoding As Encoding)

参数

stream: Stream

要读取的流。

encoding: Encoding

要使用的字符编码。

例外

ArgumentException

stream 不支持读取。

ArgumentNullException

stream 或 encoding 为 null。

示例

下面的代码示例演示了此 StreamReader 构造函数。

void getNewStreamReader()
{
   
   //Get a new StreamReader in ASCII format from a
   //file using a buffer and byte order mark detection
   StreamReader^ srAsciiFromFileFalse512 = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //file with byte order mark detection = false
   StreamReader^ srAsciiFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a file 
   StreamReader^ srAsciiFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //file with byte order mark detection = false
   StreamReader^ srFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",false );
   
   //Get a new StreamReader from a file
   StreamReader^ srFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt" );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false and a buffer
   StreamReader^ srAsciiFromStreamFalse512 = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false
   StreamReader^ srAsciiFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a FileStream
   StreamReader^ srAsciiFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //FileStream with byte order mark detection = false
   StreamReader^ srFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),false );
   
   //Get a new StreamReader from a FileStream
   StreamReader^ srFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ) );
}

private void getNewStreamReader()
{
    //Get a new StreamReader in ASCII format from a
    //file using a buffer and byte order mark detection
    StreamReader srAsciiFromFileFalse512 =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //file with byte order mark detection = false
    StreamReader srAsciiFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a file
    StreamReader srAsciiFromFile =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //file with byte order mark detection = false
    StreamReader srFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt", false);
    //Get a new StreamReader from a file
    StreamReader srFromFile =
        new StreamReader("C:\\Temp\\Test.txt");
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false and a buffer
    StreamReader srAsciiFromStreamFalse512 = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false
    StreamReader srAsciiFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a FileStream
    StreamReader srAsciiFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //FileStream with byte order mark detection = false
    StreamReader srFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        false);
    //Get a new StreamReader from a FileStream
    StreamReader srFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"));
}

Private Sub getNewStreamReader()
    Dim S As Stream = File.OpenRead("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'file using a buffer and byte order mark detection
    Dim SrAsciiFromFileFalse512 As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'file with byte order mark detection = false
    Dim SrAsciiFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a file 
    Dim SrAsciiFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'file with byte order mark detection = false        
    Dim SrFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", False)
    'Get a new StreamReader from a file
    Dim SrFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false and a buffer
    Dim SrAsciiFromStreamFalse512 As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false
    Dim SrAsciiFromStreamFalse = New StreamReader(S, _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a FileStream
    Dim SrAsciiFromStream As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'FileStream with byte order mark detection = false
    Dim SrFromStreamFalse As StreamReader = New StreamReader(S, False)
    'Get a new StreamReader from a FileStream
    Dim SrFromStream As StreamReader = New StreamReader(S)

End Sub

注解

字符编码由 encoding 参数设置，缓冲区大小设置为 1024 字节。对象 StreamReader 尝试通过查看流的前四个字节来检测编码。如果文件以适当的字节顺序标记开头，它会自动识别 UTF-8、little-endian UTF-16、big-endian UTF-16、little-endian UTF-32 和 big-endian UTF-32 文本。否则，将使用用户提供的编码。有关更多信息，请参阅 Encoding.GetPreamble 方法。

调用时StreamReader.Dispose，对象StreamReader Dispose()对提供Stream的对象调用。

注意

编译具有特定区域性设置的一组字符并检索具有不同区域性设置的相同字符时，这些字符可能无法解释，并可能导致引发异常。

有关常见 I/O 任务的列表，请参阅常见 I/O 任务。

另请参阅

适用于

StreamReader(Stream, Boolean)

Source:: StreamReader.cs

Source:: StreamReader.cs

Source:: StreamReader.cs

用指定的字节顺序标记检测选项，为指定的流初始化 StreamReader 类的一个新实例。

public:
 StreamReader(System::IO::Stream ^ stream, bool detectEncodingFromByteOrderMarks);

public StreamReader (System.IO.Stream stream, bool detectEncodingFromByteOrderMarks);

new System.IO.StreamReader : System.IO.Stream * bool -> System.IO.StreamReader

Public Sub New (stream As Stream, detectEncodingFromByteOrderMarks As Boolean)

参数

stream: Stream

要读取的流。

detectEncodingFromByteOrderMarks: Boolean

指示是否在文件头查找字节顺序标记。

例外

ArgumentException

stream 不支持读取。

ArgumentNullException

stream 为 null。

示例

下面的代码示例演示了此 StreamReader 构造函数。

void getNewStreamReader()
{
   
   //Get a new StreamReader in ASCII format from a
   //file using a buffer and byte order mark detection
   StreamReader^ srAsciiFromFileFalse512 = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //file with byte order mark detection = false
   StreamReader^ srAsciiFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a file 
   StreamReader^ srAsciiFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //file with byte order mark detection = false
   StreamReader^ srFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",false );
   
   //Get a new StreamReader from a file
   StreamReader^ srFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt" );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false and a buffer
   StreamReader^ srAsciiFromStreamFalse512 = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false
   StreamReader^ srAsciiFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a FileStream
   StreamReader^ srAsciiFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //FileStream with byte order mark detection = false
   StreamReader^ srFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),false );
   
   //Get a new StreamReader from a FileStream
   StreamReader^ srFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ) );
}

private void getNewStreamReader()
{
    //Get a new StreamReader in ASCII format from a
    //file using a buffer and byte order mark detection
    StreamReader srAsciiFromFileFalse512 =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //file with byte order mark detection = false
    StreamReader srAsciiFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a file
    StreamReader srAsciiFromFile =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //file with byte order mark detection = false
    StreamReader srFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt", false);
    //Get a new StreamReader from a file
    StreamReader srFromFile =
        new StreamReader("C:\\Temp\\Test.txt");
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false and a buffer
    StreamReader srAsciiFromStreamFalse512 = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false
    StreamReader srAsciiFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a FileStream
    StreamReader srAsciiFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //FileStream with byte order mark detection = false
    StreamReader srFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        false);
    //Get a new StreamReader from a FileStream
    StreamReader srFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"));
}

Private Sub getNewStreamReader()
    Dim S As Stream = File.OpenRead("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'file using a buffer and byte order mark detection
    Dim SrAsciiFromFileFalse512 As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'file with byte order mark detection = false
    Dim SrAsciiFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a file 
    Dim SrAsciiFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'file with byte order mark detection = false        
    Dim SrFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", False)
    'Get a new StreamReader from a file
    Dim SrFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false and a buffer
    Dim SrAsciiFromStreamFalse512 As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false
    Dim SrAsciiFromStreamFalse = New StreamReader(S, _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a FileStream
    Dim SrAsciiFromStream As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'FileStream with byte order mark detection = false
    Dim SrFromStreamFalse As StreamReader = New StreamReader(S, False)
    'Get a new StreamReader from a FileStream
    Dim SrFromStream As StreamReader = New StreamReader(S)

End Sub

注解

此构造函数使用参数将编码初始化为 UTF8Encoding、 BaseStream 属性 stream ，并将内部缓冲区大小初始化为 1024 字节。

参数 detectEncodingFromByteOrderMarks 通过查看流的前四个字节来检测编码。如果文件以适当的字节顺序标记开头，它会自动识别 UTF-8、little-endian UTF-16、big-endian UTF-16、little-endian UTF-32 和 big-endian UTF-32 文本。有关更多信息，请参阅 Encoding.GetPreamble 方法。

调用时StreamReader.Dispose，对象StreamReader Dispose()对提供Stream的对象调用。

有关常见 I/O 任务的列表，请参阅常见 I/O 任务。

另请参阅

适用于

StreamReader(String)

Source:: StreamReader.cs

Source:: StreamReader.cs

Source:: StreamReader.cs

为指定的文件名初始化 StreamReader 类的新实例。

public:
 StreamReader(System::String ^ path);

public StreamReader (string path);

new System.IO.StreamReader : string -> System.IO.StreamReader

Public Sub New (path As String)

参数

path: String

要读取的完整文件路径。

例外

ArgumentException

path 为空字符串 ("")。

ArgumentNullException

path 为 null。

FileNotFoundException

找不到该文件。

DirectoryNotFoundException

指定的路径无效，例如位于未映射的驱动器上。

IOException

path 包含不正确或无效的文件名、目录名或卷标语法。

示例

下面的代码示例演示了此 StreamReader 构造函数。

using namespace System;
using namespace System::IO;
int main()
{
   String^ path = "c:\\temp\\MyTest.txt";
   try
   {
      if ( File::Exists( path ) )
      {
         File::Delete( path );
      }
      StreamWriter^ sw = gcnew StreamWriter( path );
      try
      {
         sw->WriteLine( "This" );
         sw->WriteLine( "is some text" );
         sw->WriteLine( "to test" );
         sw->WriteLine( "Reading" );
      }
      finally
      {
         delete sw;
      }

      StreamReader^ sr = gcnew StreamReader( path );
      try
      {
         while ( sr->Peek() >= 0 )
         {
            Console::WriteLine( sr->ReadLine() );
         }
      }
      finally
      {
         delete sr;
      }
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "The process failed: {0}", e );
   }
}

using System;
using System.IO;

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

        try
        {
            if (File.Exists(path))
            {
                File.Delete(path);
            }

            using (StreamWriter sw = new StreamWriter(path))
            {
                sw.WriteLine("This");
                sw.WriteLine("is some text");
                sw.WriteLine("to test");
                sw.WriteLine("Reading");
            }

            using (StreamReader sr = new StreamReader(path))
            {
                while (sr.Peek() >= 0)
                {
                    Console.WriteLine(sr.ReadLine());
                }
            }
        }
        catch (Exception e)
        {
            Console.WriteLine("The process failed: {0}", e.ToString());
        }
    }
}

Imports System.IO

Public Class Test

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

        Try
            If File.Exists(path) Then
                File.Delete(path)
            End If

            Dim sw As StreamWriter = New StreamWriter(path)
            sw.WriteLine("This")
            sw.WriteLine("is some text")
            sw.WriteLine("to test")
            sw.WriteLine("Reading")
            sw.Close()

            Dim sr As StreamReader = New StreamReader(path)

            Do While sr.Peek() >= 0
                Console.WriteLine(sr.ReadLine())
            Loop
            sr.Close()
        Catch e As Exception
            Console.WriteLine("The process failed: {0}", e.ToString())
        End Try
    End Sub
End Class

注解

完整的文件路径由 path 参数指定。此构造函数将编码初始化为 UTF8Encoding ，并将缓冲区大小初始化为 1024 字节。

参数 path 可以是文件名，包括通用命名约定 (UNC) 共享上的文件。

参数 path 不一定是存储在磁盘上的文件;它可以是支持使用流进行访问的系统的任何部分。

注意

编译具有特定区域性设置的一组字符并检索具有不同区域性设置的相同字符时，这些字符可能无法解释，并可能导致引发异常。

有关常见 I/O 任务的列表，请参阅常见 I/O 任务。

另请参阅

适用于

StreamReader(String, Encoding)

Source:: StreamReader.cs

Source:: StreamReader.cs

Source:: StreamReader.cs

用指定的字符编码，为指定的文件名初始化 StreamReader 类的一个新实例。

public:
 StreamReader(System::String ^ path, System::Text::Encoding ^ encoding);

public StreamReader (string path, System.Text.Encoding encoding);

new System.IO.StreamReader : string * System.Text.Encoding -> System.IO.StreamReader

Public Sub New (path As String, encoding As Encoding)

参数

path: String

要读取的完整文件路径。

encoding: Encoding

要使用的字符编码。

例外

ArgumentException

path 为空字符串 ("")。

ArgumentNullException

path 或 encoding 为 null。

FileNotFoundException

找不到该文件。

DirectoryNotFoundException

指定的路径无效，例如位于未映射的驱动器上。

NotSupportedException

path 包含不正确或无效的文件名、目录名或卷标语法。

示例

下面的代码示例演示了此 StreamReader 构造函数。

void getNewStreamReader()
{
   
   //Get a new StreamReader in ASCII format from a
   //file using a buffer and byte order mark detection
   StreamReader^ srAsciiFromFileFalse512 = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //file with byte order mark detection = false
   StreamReader^ srAsciiFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a file 
   StreamReader^ srAsciiFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt",System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //file with byte order mark detection = false
   StreamReader^ srFromFileFalse = gcnew StreamReader(  "C:\\Temp\\Test.txt",false );
   
   //Get a new StreamReader from a file
   StreamReader^ srFromFile = gcnew StreamReader(  "C:\\Temp\\Test.txt" );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false and a buffer
   StreamReader^ srAsciiFromStreamFalse512 = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false,512 );
   
   //Get a new StreamReader in ASCII format from a
   //FileStream with byte order mark detection = false
   StreamReader^ srAsciiFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII,false );
   
   //Get a new StreamReader in ASCII format from a FileStream
   StreamReader^ srAsciiFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),System::Text::Encoding::ASCII );
   
   //Get a new StreamReader from a
   //FileStream with byte order mark detection = false
   StreamReader^ srFromStreamFalse = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ),false );
   
   //Get a new StreamReader from a FileStream
   StreamReader^ srFromStream = gcnew StreamReader( File::OpenRead(  "C:\\Temp\\Test.txt" ) );
}

private void getNewStreamReader()
{
    //Get a new StreamReader in ASCII format from a
    //file using a buffer and byte order mark detection
    StreamReader srAsciiFromFileFalse512 =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //file with byte order mark detection = false
    StreamReader srAsciiFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a file
    StreamReader srAsciiFromFile =
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //file with byte order mark detection = false
    StreamReader srFromFileFalse =
        new StreamReader("C:\\Temp\\Test.txt", false);
    //Get a new StreamReader from a file
    StreamReader srFromFile =
        new StreamReader("C:\\Temp\\Test.txt");
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false and a buffer
    StreamReader srAsciiFromStreamFalse512 = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a
    //FileStream with byte order mark detection = false
    StreamReader srAsciiFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a FileStream
    StreamReader srAsciiFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a
    //FileStream with byte order mark detection = false
    StreamReader srFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        false);
    //Get a new StreamReader from a FileStream
    StreamReader srFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"));
}

Private Sub getNewStreamReader()
    Dim S As Stream = File.OpenRead("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'file using a buffer and byte order mark detection
    Dim SrAsciiFromFileFalse512 As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'file with byte order mark detection = false
    Dim SrAsciiFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a file 
    Dim SrAsciiFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'file with byte order mark detection = false        
    Dim SrFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", False)
    'Get a new StreamReader from a file
    Dim SrFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false and a buffer
    Dim SrAsciiFromStreamFalse512 As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false
    Dim SrAsciiFromStreamFalse = New StreamReader(S, _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a FileStream
    Dim SrAsciiFromStream As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'FileStream with byte order mark detection = false
    Dim SrFromStreamFalse As StreamReader = New StreamReader(S, False)
    'Get a new StreamReader from a FileStream
    Dim SrFromStream As StreamReader = New StreamReader(S)

End Sub

注解

此构造函数初始化参数 encoding 指定的编码，并将内部缓冲区大小初始化为 1024 字节。对象 StreamReader 尝试通过查看流的前四个字节来检测编码。如果文件以适当的字节顺序标记开头，它会自动识别 UTF-8、little-endian UTF-16、big-endian UTF-16、little-endian UTF-32 和 big-endian UTF-32 文本。否则，将使用用户提供的编码。有关更多信息，请参阅 Encoding.GetPreamble 方法。

参数 path 可以是文件名，包括通用命名约定 (UNC) 共享上的文件。

参数 path 不一定是存储在磁盘上的文件;它可以是支持使用流进行访问的系统的任何部分。

注意

编译具有特定区域性设置的一组字符并检索具有不同区域性设置的相同字符时，这些字符可能无法解释，并可能导致引发异常。

有关常见 I/O 任务的列表，请参阅常见 I/O 任务。

另请参阅

适用于