Stream Class

 

Provides a generic view of a sequence of bytes. This is an abstract class.

To browse the .NET Framework source code for this type, see the Reference Source.

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


<SerializableAttribute>
<ComVisibleAttribute(True)>
Public MustInherit Class Stream
	Inherits MarshalByRefObject
	Implements IDisposable

NameDescription
System_CAPS_protmethodStream()

Initializes a new instance of the Stream class.

NameDescription
System_CAPS_pubpropertyCanRead

When overridden in a derived class, gets a value indicating whether the current stream supports reading.

System_CAPS_pubpropertyCanSeek

When overridden in a derived class, gets a value indicating whether the current stream supports seeking.

System_CAPS_pubpropertyCanTimeout

Gets a value that determines whether the current stream can time out.

System_CAPS_pubpropertyCanWrite

When overridden in a derived class, gets a value indicating whether the current stream supports writing.

System_CAPS_pubpropertyLength

When overridden in a derived class, gets the length in bytes of the stream.

System_CAPS_pubpropertyPosition

When overridden in a derived class, gets or sets the position within the current stream.

System_CAPS_pubpropertyReadTimeout

Gets or sets a value, in miliseconds, that determines how long the stream will attempt to read before timing out.

System_CAPS_pubpropertyWriteTimeout

Gets or sets a value, in miliseconds, that determines how long the stream will attempt to write before timing out.

NameDescription
System_CAPS_pubmethodBeginRead(Byte(), Int32, Int32, AsyncCallback, Object)

Begins an asynchronous read operation. (Consider using ReadAsync instead; see the Remarks section.)

System_CAPS_pubmethodBeginWrite(Byte(), Int32, Int32, AsyncCallback, Object)

Begins an asynchronous write operation. (Consider using WriteAsync instead; see the Remarks section.)

System_CAPS_pubmethodClose()

Closes the current stream and releases any resources (such as sockets and file handles) associated with the current stream. Instead of calling this method, ensure that the stream is properly disposed.

System_CAPS_pubmethodCopyTo(Stream)

Reads the bytes from the current stream and writes them to another stream.

System_CAPS_pubmethodCopyTo(Stream, Int32)

Reads the bytes from the current stream and writes them to another stream, using a specified buffer size.

System_CAPS_pubmethodCopyToAsync(Stream)

Asynchronously reads the bytes from the current stream and writes them to another stream.

System_CAPS_pubmethodCopyToAsync(Stream, Int32)

Asynchronously reads the bytes from the current stream and writes them to another stream, using a specified buffer size.

System_CAPS_pubmethodCopyToAsync(Stream, Int32, CancellationToken)

Asynchronously reads the bytes from the current stream and writes them to another stream, using a specified buffer size and cancellation token.

System_CAPS_pubmethodCreateObjRef(Type)

Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object.(Inherited from MarshalByRefObject.)

System_CAPS_protmethodCreateWaitHandle()

Obsolete.Allocates a WaitHandle object.

System_CAPS_pubmethodDispose()

Releases all resources used by the Stream.

System_CAPS_protmethodDispose(Boolean)

Releases the unmanaged resources used by the Stream and optionally releases the managed resources.

System_CAPS_pubmethodEndRead(IAsyncResult)

Waits for the pending asynchronous read to complete. (Consider using ReadAsync instead; see the Remarks section.)

System_CAPS_pubmethodEndWrite(IAsyncResult)

Ends an asynchronous write operation. (Consider using WriteAsync instead; see the Remarks section.)

System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethodFinalize()

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethodFlush()

When overridden in a derived class, clears all buffers for this stream and causes any buffered data to be written to the underlying device.

System_CAPS_pubmethodFlushAsync()

Asynchronously clears all buffers for this stream and causes any buffered data to be written to the underlying device.

System_CAPS_pubmethodFlushAsync(CancellationToken)

Asynchronously clears all buffers for this stream, causes any buffered data to be written to the underlying device, and monitors cancellation requests.

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetLifetimeService()

Retrieves the current lifetime service object that controls the lifetime policy for this instance.(Inherited from MarshalByRefObject.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethodInitializeLifetimeService()

Obtains a lifetime service object to control the lifetime policy for this instance.(Inherited from MarshalByRefObject.)

System_CAPS_protmethodMemberwiseClone()

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_protmethodMemberwiseClone(Boolean)

Creates a shallow copy of the current MarshalByRefObject object.(Inherited from MarshalByRefObject.)

System_CAPS_protmethodObjectInvariant()

Obsolete. This API supports the product infrastructure and is not intended to be used directly from your code. Provides support for a Contract.

System_CAPS_pubmethodRead(Byte(), Int32, Int32)

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.

System_CAPS_pubmethodReadAsync(Byte(), Int32, Int32)

Asynchronously reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read.

System_CAPS_pubmethodReadAsync(Byte(), Int32, Int32, CancellationToken)

Asynchronously reads a sequence of bytes from the current stream, advances the position within the stream by the number of bytes read, and monitors cancellation requests.

System_CAPS_pubmethodReadByte()

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.

System_CAPS_pubmethodSeek(Int64, SeekOrigin)

When overridden in a derived class, sets the position within the current stream.

System_CAPS_pubmethodSetLength(Int64)

When overridden in a derived class, sets the length of the current stream.

System_CAPS_pubmethodSystem_CAPS_staticSynchronized(Stream)

Creates a thread-safe (synchronized) wrapper around the specified Stream object.

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

System_CAPS_pubmethodWrite(Byte(), Int32, Int32)

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.

System_CAPS_pubmethodWriteAsync(Byte(), Int32, Int32)

Asynchronously writes a sequence of bytes to the current stream and advances the current position within this stream by the number of bytes written.

System_CAPS_pubmethodWriteAsync(Byte(), Int32, Int32, CancellationToken)

Asynchronously writes a sequence of bytes to the current stream, advances the current position within this stream by the number of bytes written, and monitors cancellation requests.

System_CAPS_pubmethodWriteByte(Byte)

Writes a byte to the current position in the stream and advances the position within the stream by one byte.

NameDescription
System_CAPS_pubfieldSystem_CAPS_staticNull

A Stream with no backing store.

System_CAPS_noteNote

To view the .NET Framework source code for this type, see the Reference Source. You can browse through the source code online, download the reference for offline viewing, and step through the sources (including patches and updates) during debugging; see instructions.

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, and isolate the programmer from the specific details of the operating system and the underlying devices.

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 refers to querying and modifying 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.

Some of the more commonly used streams that inherit from Stream are FileStream, and MemoryStream.

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

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.

This type implements the IDisposable interface. When you have finished using the type, you should dispose of it either directly or indirectly. To dispose of the type directly, call its Dispose method in a try/catch block. To dispose of it indirectly, use a language construct such as using (in C#) or Using (in Visual Basic). For more information, see the “Using an Object that Implements IDisposable” section in the IDisposable interface topic.

Disposing a Stream object flushes any buffered data, and essentially calls the Flush method for you. Dispose also releases operating system resources such as file handles, network connections, or memory used for any internal buffering. The BufferedStream class provides the capability of wrapping a buffered stream around another stream in order to improve read and write performance.

Starting with the .NET Framework 4.5, the Stream class includes async methods to simplify asynchronous operations. An async method contains Async in its name, such as ReadAsync, WriteAsync, CopyToAsync, and FlushAsync. These methods enable you to perform resource-intensive I/O operations without blocking the main thread. This performance consideration is particularly important in a Windows 8.x Store app or desktop app where a time-consuming stream operation can block the UI thread and make your app appear as if it is not working. The async methods are used in conjunction with the async and await keywords in Visual Basic and C#.

When used in a Windows 8.x Store app, Stream includes two extension methods: AsInputStream and AsOutputStream. These methods convert a Stream object to a stream in the Windows Runtime. You can also convert a stream in the Windows Runtime to a Stream object by using the AsStreamForRead and AsStreamForWrite methods. For more information, see How to: Convert Between .NET Framework Streams and Windows Runtime Streams

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

If you need a stream with no backing store (also known as a bit bucket), use the Null field to retrieve an instance of a stream that is designed for this purpose.

Notes to Implementers:

When you implement a derived class of Stream, you must provide implementations for the Read and Write methods. The asynchronous methods ReadAsync, WriteAsync, and CopyToAsync use the synchronous methods Read and Write in their implementations. Therefore, 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 you derive from Stream, we recommend that you override these methods to access your internal buffer, if you have one, 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 the Stream cleanup logic in the Dispose method. For more information, see Implementing a Dispose Method.

The following example demonstrates how to use two FileStream objects to asynchronously copy the files from one directory to another directory. The FileStream class derives from the Stream class. Notice that the Click event handler for the Button control is marked with the async modifier because it calls an asynchronous method.

Imports System.IO

Class MainWindow

    Private Async Sub Button_Click(sender As Object, e As RoutedEventArgs)
        Dim StartDirectory As String = "c:\Users\exampleuser\start"
        Dim EndDirectory As String = "c:\Users\exampleuser\end"

        For Each filename As String In Directory.EnumerateFiles(StartDirectory)
            Using SourceStream As FileStream = File.Open(filename, FileMode.Open)
                Using DestinationStream As FileStream = File.Create(EndDirectory + filename.Substring(filename.LastIndexOf("\"c)))
                    Await SourceStream.CopyToAsync(DestinationStream)
                End Using

            End Using
        Next
    End Sub

End Class

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1

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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