아티클
11/18/2011

FileStream Class

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

When it is called by an elevated-trust application, exposes a Stream around a file, supporting both synchronous and asynchronous read and write operations.

Inheritance Hierarchy

System.Object
  System.IO.Stream
    System.IO.FileStream
      System.IO.IsolatedStorage.IsolatedStorageFileStream

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

Syntax

'Declaration
<ComVisibleAttribute(True)> _
Public Class FileStream _
    Inherits Stream

[ComVisibleAttribute(true)]
public class FileStream : Stream

The FileStream type exposes the following members.

Constructors

	Name	Description
	FileStream(String, FileMode)	When it is called by trusted applications, initializes a new instance of the FileStream class with the specified path and creation mode.
	FileStream(String, FileMode, FileAccess)	When it is called by trusted applications, initializes a new instance of the FileStream class with the specified path, creation mode, and read/write permission.
	FileStream(String, FileMode, FileAccess, FileShare)	When it is called by trusted applications, initializes a new instance of the FileStream class with the specified path, creation mode, read/write permission, and sharing permission.
	FileStream(String, FileMode, FileAccess, FileShare, Int32)	When it is called by trusted applications, initializes a new instance of the FileStream class with the specified path, creation mode, read/write and sharing permission, and buffer size.

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Properties

	Name	Description
	CanRead	Gets a value indicating whether the current stream supports reading. (Overrides Stream.CanRead.)
	CanSeek	Gets a value indicating whether the current stream supports seeking. (Overrides Stream.CanSeek.)
	CanTimeout	Gets a value that determines whether the current stream can time out. (Inherited from Stream.)
	CanWrite	Gets a value indicating whether the current stream supports writing. (Overrides Stream.CanWrite.)
	Length	When it is called by trusted applications, gets the length in bytes of the stream. (Overrides Stream.Length.)
	Name	When it is called by trusted applications, gets the name of the file stream that was passed to the constructor.
	Position	When it is called by trusted applications, gets or sets the current position of this stream. (Overrides Stream.Position.)
	ReadTimeout	Gets or sets a value, in miliseconds, that determines how long the stream will attempt to read before timing out. (Inherited from Stream.)
	WriteTimeout	Gets or sets a value, in miliseconds, that determines how long the stream will attempt to write before timing out. (Inherited from Stream.)

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Methods

	Name	Description
	BeginRead	Begins an asynchronous read. (Overrides Stream.BeginRead(array<Byte[], Int32, Int32, AsyncCallback, Object).)
	BeginWrite	Begins an asynchronous write. (Overrides Stream.BeginWrite(array<Byte[], Int32, Int32, AsyncCallback, Object).)
	Close	Closes the current stream and releases any resources (such as sockets and file handles) associated with the current stream. (Inherited from Stream.)
	CopyTo(Stream)	Reads all the bytes from the current stream and writes them to the destination stream. (Inherited from Stream.)
	CopyTo(Stream, Int32)	Reads all the bytes from the current stream and writes them to a destination stream, using a specified buffer size. (Inherited from Stream.)
	Dispose()	Releases all resources used by the Stream. (Inherited from Stream.)
	Dispose(Boolean)	Releases the unmanaged resources used by the FileStream and optionally releases the managed resources. (Overrides Stream.Dispose(Boolean).)
	EndRead	Waits for the pending asynchronous read to complete. (Overrides Stream.EndRead(IAsyncResult).)
	EndWrite	Ends an asynchronous write, blocking until the I/O operation has completed. (Overrides Stream.EndWrite(IAsyncResult).)
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Finalize	Ensures that resources are freed and other cleanup operations are performed when the garbage collector reclaims the FileStream. (Overrides Object.Finalize().)
	Flush()	Clears all buffers for this stream and causes any buffered data to be written to the file system. (Overrides Stream.Flush().)
	Flush(Boolean)	Clears buffers for this stream and causes any buffered data to be written to the file, and also clears all intermediate file buffers.
	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	Reads a block of bytes from the stream and writes the data in a given buffer. (Overrides Stream.Read(array<Byte[], Int32, Int32).)
	ReadByte	Reads a byte from the file and advances the read position one byte. (Overrides Stream.ReadByte().)
	Seek	Sets the current position of this stream to the given value. (Overrides Stream.Seek(Int64, SeekOrigin).)
	SetLength	Sets the length of this stream to the given value. (Overrides Stream.SetLength(Int64).)
	ToString	Returns a string that represents the current object. (Inherited from Object.)
	Write	Writes a block of bytes to this stream using data from a buffer. (Overrides Stream.Write(array<Byte[], Int32, Int32).)
	WriteByte	Writes a byte to the current position in the file stream. (Overrides Stream.WriteByte(Byte).)

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Remarks

Platform Notes

Silverlight for Windows Phone

This type is present to support the .NET Compact Framework infrastructure in Silverlight for Windows Phone, and it is not intended to be used in your application code.

Examples

The following example displays an image picked at random from the user's My Pictures folder. It uses the DirectoryInfo class to obtain an enumerable collection of FileInfo objects that represent files that have a .jpg or .png extension. That collection is used to construct a List<T> collection so that an index can be used to select a file that corresponds to the random number.

The example then creates a bitmap image by using the FileStream class and sets it as the source for an Image control (named MyImage).

For example code and information about how to create an application that runs outside the browser, see Out-of-Browser Support.

Private Sub LoadImage()

    If Application.Current.HasElevatedPermissions Then
        Dim di As New DirectoryInfo(Environment.GetFolderPath(Environment.SpecialFolder.MyPictures))

        Dim files = From f In di.EnumerateFiles() _
            Where f.Extension.ToLower() = ".jpg" OrElse f.Extension = ".png" _
            Select f

        Dim max As Integer = files.Count() + 1

        Dim rnd As New Random()
        Dim r As Integer = rnd.[Next](0, max)

        Dim pics As New List(Of FileInfo)(files)

        Dim randpic As String = pics(r).FullName

        Dim img As New BitmapImage()
        img.SetSource(New FileStream(randpic, FileMode.Open))


        MyImage.Source = img
    End If
End Sub

private void LoadImage()
{

    if (Application.Current.HasElevatedPermissions)
    {
        DirectoryInfo di = new DirectoryInfo(Environment.GetFolderPath(
           Environment.SpecialFolder.MyPictures));

        var files = from f in di.EnumerateFiles()
                    where f.Extension.ToLower() == ".jpg" || 
                        f.Extension == ".png"
                    select f;

        int max = files.Count() + 1;

        Random rnd = new Random();
        int r = rnd.Next(0, max);

        List<FileInfo> pics = new List<FileInfo>(files);

        string randpic = pics[r].FullName;

        BitmapImage img = new BitmapImage();
        img.SetSource(new FileStream(randpic, FileMode.Open));

        MyImage.Source = img;

    }
}

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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