通过

BufferedStream.Read 方法

  • 项目

将字节从当前缓冲流复制到数组。

**命名空间:**System.IO
**程序集:**mscorlib（在 mscorlib.dll 中）

语法

声明
Public Overrides Function Read ( _
    <InAttribute> <OutAttribute> array As Byte(), _
    offset As Integer, _
    count As Integer _
) As Integer
用法
Dim instance As BufferedStream
Dim array As Byte()
Dim offset As Integer
Dim count As Integer
Dim returnValue As Integer

returnValue = instance.Read(array, offset, count)

public override int Read (
    [InAttribute] [OutAttribute] byte[] array,
    int offset,
    int count
)

public:
virtual int Read (
    [InAttribute] [OutAttribute] array<unsigned char>^ array, 
    int offset, 
    int count
) override

public int Read (
    /** @attribute InAttribute() */ /** @attribute OutAttribute() */ byte[] array, 
    int offset, 
    int count
)

public override function Read (
    array : byte[], 
    offset : int, 
    count : int
) : int

参数

  • array
    将字节复制到的缓冲区。
  • offset
    缓冲区中的字节偏移量，从此处开始读取字节。
  • count
    要读取的字节数。

返回值

读入 array 中的总字节数。如果可用的字节没有所请求的那么多，总字节数可能小于请求的字节数；或者如果在可读取任何数据前就已到达流的末尾，则为零。

异常

异常类型 条件

ArgumentException

array 的长度减去 offset 小于 count。

ArgumentNullException

array 为 空引用（在 Visual Basic 中为 Nothing）。

ArgumentOutOfRangeException

offset 或 count 为负。

IOException

流未打开或为 空引用（在 Visual Basic 中为 Nothing）。

NotSupportedException

流不支持读取。

ObjectDisposedException

在流关闭后调用方法。

备注

有关创建文件和向文件中写入文本的示例，请参见 如何：向文件写入文本。有关从文件中读取文本的示例，请参见 如何：从文件读取文本。有关读取和写入二进制文件的示例，请参见 如何：对新建的数据文件进行读取和写入。

仅当到达流的末尾时，Read 方法才会返回零。在所有其他情况中，Read 总是在返回前从流中读取至少一个字节。根据定义，如果调用 Read 时流中没有数据可用，则 Read 方法返回零（自动到达流的末尾）。即使尚未到达流的末尾，实现仍可以随意返回少于所请求的字节。

将 BinaryReader 用于读取基元数据类型。

示例

此代码示例摘自一个为 BufferedStream 类提供的更大的示例。

' Receive data using the BufferedStream.
Console.WriteLine("Receiving data using BufferedStream.")
bytesReceived = 0
startTime = DateTime.Now
While bytesReceived < numberOfLoops * receivedData.Length
    bytesReceived += bufStream.Read( _
        receivedData, 0, receivedData.Length)
End While
bufferedTime = DateTime.Now.Subtract(startTime).TotalSeconds
Console.WriteLine("{0} bytes received in {1} " & _
    "seconds." & vbCrLf, _
    bytesReceived.ToString(), _
    bufferedTime.ToString("F1"))

// Receive data using the BufferedStream.
Console.WriteLine("Receiving data using BufferedStream.");
bytesReceived = 0;
startTime = DateTime.Now;
while(bytesReceived < numberOfLoops * receivedData.Length)
{
    bytesReceived += bufStream.Read(
        receivedData, 0, receivedData.Length);
}
bufferedTime = (DateTime.Now - startTime).TotalSeconds;
Console.WriteLine("{0} bytes received in {1} seconds.\n",
    bytesReceived.ToString(), 
    bufferedTime.ToString("F1"));

// Receive data using the BufferedStream.
Console::WriteLine(  "Receiving data using BufferedStream." );
bytesReceived = 0;
startTime = DateTime::Now;
while ( bytesReceived < numberOfLoops * receivedData->Length )
{
   bytesReceived += bufStream->Read( receivedData, 0, receivedData->Length );
}

bufferedTime = (DateTime::Now - startTime).TotalSeconds;
Console::WriteLine( "{0} bytes received in {1} seconds.\n", bytesReceived.ToString(), bufferedTime.ToString(  "F1" ) );

// Receive data using the BufferedStream.
Console.WriteLine("Receiving data using BufferedStream.");
bytesReceived = 0;
startTime = DateTime.get_Now();
while((bytesReceived < numberOfLoops * receivedData.length)) {
    bytesReceived += bufStream.Read(receivedData,0,receivedData.length);
}
bufferedTime =
    ((DateTime.get_Now()).Subtract(startTime)).get_TotalSeconds();
Console.WriteLine("{0} bytes received in {1} seconds.\n",
    (new Integer(bytesReceived)).ToString(),
    ((System.Double) bufferedTime).ToString("F1"));

平台

Windows 98、Windows 2000 SP4、Windows Millennium Edition、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

请参见

参考

BufferedStream 类
BufferedStream 成员
System.IO 命名空间
BlockCopy
CanRead
Write

其他资源

文件和流 I/O
如何：从文件读取文本
如何：向文件写入文本