TextReader 类
表示可读取连续字符系列的读取器。
**命名空间:**System.IO
**程序集:**mscorlib（在 mscorlib.dll 中）
语法
声明
<SerializableAttribute> _
<ComVisibleAttribute(True)> _
Public MustInherit Class TextReader
Inherits MarshalByRefObject
Implements IDisposable
用法
Dim instance As TextReader
[SerializableAttribute]
[ComVisibleAttribute(true)]
public abstract class TextReader : MarshalByRefObject, IDisposable
[SerializableAttribute]
[ComVisibleAttribute(true)]
public ref class TextReader abstract : public MarshalByRefObject, IDisposable
/** @attribute SerializableAttribute() */
/** @attribute ComVisibleAttribute(true) */
public abstract class TextReader extends MarshalByRefObject implements IDisposable
SerializableAttribute
ComVisibleAttribute(true)
public abstract class TextReader extends MarshalByRefObject implements IDisposable
备注
TextReader 为 StreamReader 和 StringReader 的抽象基类，它们分别从流和字符串读取字符。使用这些派生类可打开一个文本文件以读取指定范围的字符，或基于现有的流创建一个读取器。
为了生成有用的 TextReader 的实例，派生类最低限度必须实现 Peek 和 Read 方法。
示例
下面的代码示例阐释了 TextReader 和 TextWriter 两种类型的多态行为。由于 aStringWriter 和 aStreamWriter 都属于 TextWriter 类型，因此 WriteVowel 方法会同时用这两个对象调用，并且会执行与每个特定类型关联的 Write 方法。同样，ReadText 方法会同时用 aStringReader 和 aStreamReader 调用，并且会执行适当的 ReadToEnd 方法。请注意，对于 aStringWriter 和 aStringReader，备份是字符串；而对于 aStreamWriter 和 aStreamReader，备份是文件。
Imports System
Imports System.IO
Public Class TextRW
Shared Sub Main()
Dim aStringWriter, aStreamWriter As TextWriter
aStringWriter = New StringWriter()
aStreamWriter = New StreamWriter("InvalidPathChars.txt")
WriteText(aStringWriter)
WriteText(aStreamWriter)
aStreamWriter.Close()
Dim aStringReader, aStreamReader As TextReader
aStringReader = New StringReader(aStringWriter.ToString())
aStreamReader = New StreamReader("InvalidPathChars.txt")
ReadText(aStringReader)
ReadText(aStreamReader)
aStreamReader.Close()
End Sub
Shared Sub WriteText(aTextWriter As TextWriter)
aTextWriter.Write("Invalid file path characters are: ")
aTextWriter.Write(Path.InvalidPathChars)
aTextWriter.Write("."C)
End Sub
Shared Sub ReadText(aTextReader As TextReader)
Console.WriteLine("From {0} - {1}", _
aTextReader.GetType().Name, aTextReader.ReadToEnd())
End Sub
End Class
using System;
using System.IO;
class TextRW
{
static void Main()
{
TextWriter stringWriter = new StringWriter();
using(TextWriter streamWriter =
new StreamWriter("InvalidPathChars.txt"))
{
WriteText(stringWriter);
WriteText(streamWriter);
}
TextReader stringReader =
new StringReader(stringWriter.ToString());
using(TextReader streamReader =
new StreamReader("InvalidPathChars.txt"))
{
ReadText(stringReader);
ReadText(streamReader);
}
}
static void WriteText(TextWriter textWriter)
{
textWriter.Write("Invalid file path characters are: ");
textWriter.Write(Path.InvalidPathChars);
textWriter.Write('.');
}
static void ReadText(TextReader textReader)
{
Console.WriteLine("From {0} - {1}",
textReader.GetType().Name, textReader.ReadToEnd());
}
}
using namespace System;
using namespace System::IO;
void WriteText( TextWriter^ textWriter )
{
textWriter->Write( "Invalid file path characters are: " );
textWriter->Write( Path::InvalidPathChars );
textWriter->Write( Char::Parse( "." ) );
}
void ReadText( TextReader^ textReader )
{
Console::WriteLine( "From {0} - {1}", textReader->GetType()->Name, textReader->ReadToEnd() );
}
int main()
{
TextWriter^ stringWriter = gcnew StringWriter;
TextWriter^ streamWriter = gcnew StreamWriter( "InvalidPathChars.txt" );
WriteText( stringWriter );
WriteText( streamWriter );
streamWriter->Close();
TextReader^ stringReader = gcnew StringReader( stringWriter->ToString() );
TextReader^ streamReader = gcnew StreamReader( "InvalidPathChars.txt" );
ReadText( stringReader );
ReadText( streamReader );
streamReader->Close();
}
import System.*;
import System.IO.*;
class TextRW
{
public static void main(String[] args)
{
TextWriter stringWriter = new StringWriter();
TextWriter streamWriter = new StreamWriter("InvalidPathChars.txt");
try {
WriteText(stringWriter);
WriteText(streamWriter);
}
finally {
streamWriter.Dispose();
}
TextReader stringReader = new StringReader(stringWriter.ToString());
TextReader streamReader = new StreamReader("InvalidPathChars.txt");
try {
ReadText(stringReader);
ReadText(streamReader);
}
finally {
streamReader.Dispose();
}
} //main
static void WriteText(TextWriter textWriter)
{
textWriter.Write("Invalid file path characters are: ");
textWriter.Write(Path.InvalidPathChars);
textWriter.Write('.');
} //WriteText
static void ReadText(TextReader textReader)
{
Console.WriteLine("From {0} - {1}",
textReader.GetType().get_Name(),textReader.ReadToEnd());
} //ReadText
} //TextRW
继承层次结构
System.Object
System.MarshalByRefObject
System.IO.TextReader
System.IO.StreamReader
System.IO.StringReader
线程安全
此类型的任何公共静态（Visual Basic 中的 Shared）成员都是线程安全的，但不保证所有实例成员都是线程安全的。
平台
Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition
.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。
版本信息
.NET Framework
受以下版本支持：2.0、1.1、1.0
.NET Compact Framework
受以下版本支持：2.0、1.0