Статья
11/18/2011

Stream Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Provides a generic view of a sequence of bytes.

Inheritance Hierarchy

System.Object
  System.IO.Stream
    System.IO.FileStream
    System.IO.MemoryStream
    System.IO.UnmanagedMemoryStream
    System.Security.Cryptography.CryptoStream

Namespace: System.IO
Assembly: mscorlib (in mscorlib.dll)

Syntax

'Declaration
<ComVisibleAttribute(True)> _
Public MustInherit Class Stream _
    Implements IDisposable

[ComVisibleAttribute(true)]
public abstract class Stream : IDisposable

The Stream type exposes the following members.

Constructors

	Name	Description
	Stream	Initializes a new instance of the Stream class.

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Properties

	Name	Description
	CanRead	When overridden in a derived class, gets a value indicating whether the current stream supports reading.
	CanSeek	When overridden in a derived class, gets a value indicating whether the current stream supports seeking.
	CanTimeout	Gets a value that determines whether the current stream can time out.
	CanWrite	When overridden in a derived class, gets a value indicating whether the current stream supports writing.
	Length	When overridden in a derived class, gets the length in bytes of the stream.
	Position	When overridden in a derived class, gets or sets the position within the current stream.
	ReadTimeout	Gets or sets a value, in miliseconds, that determines how long the stream will attempt to read before timing out.
	WriteTimeout	Gets or sets a value, in miliseconds, that determines how long the stream will attempt to write before timing out.

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Methods

	Name	Description
	BeginRead	Begins an asynchronous read operation.
	BeginWrite	Begins an asynchronous write operation.
	Close	Closes the current stream and releases any resources (such as sockets and file handles) associated with the current stream.
	CopyTo(Stream)	Reads all the bytes from the current stream and writes them to the destination stream.
	CopyTo(Stream, Int32)	Reads all the bytes from the current stream and writes them to a destination stream, using a specified buffer size.
	Dispose()	Releases all resources used by the Stream.
	Dispose(Boolean)	Releases the unmanaged resources used by the Stream and optionally releases the managed resources.
	EndRead	Waits for the pending asynchronous read to complete.
	EndWrite	Ends an asynchronous write operation.
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	Flush	When overridden in a derived class, clears all buffers for this stream and causes any buffered data to be written to the underlying device.
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	Read	When overridden in a derived class, reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read.
	ReadByte	Reads a byte from the stream and advances the position within the stream by one byte, or returns -1 if at the end of the stream.
	Seek	When overridden in a derived class, sets the position within the current stream.
	SetLength	When overridden in a derived class, sets the length of the current stream.
	ToString	Returns a string that represents the current object. (Inherited from Object.)
	Write	When overridden in a derived class, writes a sequence of bytes to the current stream and advances the current position within this stream by the number of bytes written.
	WriteByte	Writes a byte to the current position in the stream and advances the position within the stream by one byte.

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Fields

	Name	Description
	Null	A Stream with no backing store.

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Remarks

Streams involve three fundamental operations:

You can read from streams. Reading is the transfer of data from a stream into a data structure, such as an array of bytes.
You can write to streams. Writing is the transfer of data from a data structure into a stream.
Streams can support seeking. Seeking is the querying and modifying of the current position within a stream. Seek capability depends on the kind of backing store a stream has. For example, network streams have no unified concept of a current position, and therefore typically do not support seeking.

Stream is the abstract base class of all streams. A stream is an abstraction of a sequence of bytes, such as a file, an input/output device, an inter-process communication pipe, or a TCP/IP socket. The Stream class and its derived classes provide a generic view of these different types of input and output, isolating the programmer from the specific details of the operating system and the underlying devices.

Depending on the underlying data source or repository, streams might support only some of these capabilities. An application can query a stream for its capabilities by using the CanRead, CanWrite, and CanSeek properties.

The Read and Write methods read and write data in a variety of formats. For streams that support seeking, use the Seek and SetLength methods and the Position and Length properties to query and modify the current position and length of a stream.

Some stream implementations perform local buffering of the underlying data to improve performance. For such streams, the Flush method can be used to clear any internal buffers and ensure that all data has been written to the underlying data source or repository.

Calling Close on a Stream flushes any buffered data, essentially calling Flush for you. Close also releases operating system resources such as file handles, network connections, or memory used for any internal buffering.

If you need a stream with no backing store (also known as a bit bucket), use Null.

Notes to Implementers

When implementing a derived class of Stream, you must provide implementations for the Read and Write methods. The asynchronous methods BeginRead, EndRead, BeginWrite, and EndWrite are implemented through the synchronous methods Read and Write. Similarly, your implementations of Read and Write will work correctly with the asynchronous methods. The default implementations of ReadByte and WriteByte create a new single-element byte array, and then call your implementations of Read and Write. When deriving from Stream, if you have an internal byte buffer, it is strongly recommended that you override these methods to access your internal buffer for substantially better performance. You must also provide implementations of CanRead, CanSeek, CanWrite, Flush, Length, Position, Seek, and SetLength.

Do not override the Close method, instead, put all of the Stream cleanup logic in the Dispose method.

Topic	Location
How to: Write Text to a File	.NET Framework: Programming Fundamentals
How to: Read Text from a File	.NET Framework: Programming Fundamentals
How to: Write Text to a File	.NET Framework: Programming Fundamentals
How to: Read Text from a File	.NET Framework: Programming Fundamentals
How to: Write Text to a File	.NET Framework: Programming Fundamentals
How to: Read Text from a File	.NET Framework: Programming Fundamentals

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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