FileStream

Package	flash.filesystem
Class	public class FileStream
Inheritance	FileStream EventDispatcher Object
Implements	IDataInput, IDataOutput

Runtime Versions:

AIR 1.0

A FileStream object is used to read and write files. Files can be opened synchronously by calling the open() method or asynchronously by calling the openAsync() method.

The advantage of opening files asynchronously is that other code can execute while Adobe AIR runs read and write processes in the background. When opened asynchronously, progress events are dispatched as operations proceed.

A File object that is opened synchronously behaves much like a ByteArray object; a file opened asynchronously behaves much like a Socket or URLStream object. When a File object is opened synchronously, the caller pauses while the requested data is read from or written to the underlying file. When opened asynchronously, any data written to the stream is immediately buffered and later written to the file.

Whether reading from a file synchronously or asynchronously, the actual read methods are synchronous. In both cases they read from data that is currently "available." The difference is that when reading synchronously all of the data is available at all times, and when reading asynchronously data becomes available gradually as the data streams into a read buffer. Either way, the data that can be synchronously read at the current moment is represented by the bytesAvailable property.

An application that is processing asynchronous input typically registers for progress events and consumes the data as it becomes available by calling read methods. Alternatively, an application can simply wait until all of the data is available by registering for the complete event and processing the entire data set when the complete event is dispatched.

More examples

Reading and writing files

Public Properties

Hide Inherited Public Properties

Show Inherited Public Properties

	Property		Defined By
		bytesAvailable : uint [read-only] Returns the number of bytes of data available for reading in the input buffer.	FileStream
		constructor : Object A reference to the class object or constructor function for a given object instance.	Object
		endian : String The byte order for the data, either the BIG_ENDIAN or LITTLE_ENDIAN constant from the Endian class.	FileStream
		objectEncoding : uint Specifies whether the AMF3 or AMF0 format is used when writing or reading binary data by using the readObject() or writeObject() method.	FileStream
		position : Number The current position in the file.	FileStream
		readAhead : Number The minimum amount of data to read from disk when reading files asynchronously.	FileStream

Public Methods

Hide Inherited Public Methods

Show Inherited Public Methods

	Method		Defined By
		FileStream() Creates a FileStream object.	FileStream
		addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event.	EventDispatcher
		close():void Closes the FileStream object.	FileStream
		dispatchEvent(event:Event):Boolean Dispatches an event into the event flow.	EventDispatcher
		hasEventListener(type:String):Boolean Checks whether the EventDispatcher object has any listeners registered for a specific type of event.	EventDispatcher
		hasOwnProperty(name:String):Boolean Indicates whether an object has a specified property defined.	Object
		isPrototypeOf(theClass:Object):Boolean Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.	Object
		open(file:File, fileMode:String):void Opens the FileStream object synchronously, pointing to the file specified by the file parameter.	FileStream
		openAsync(file:File, fileMode:String):void Opens the FileStream object asynchronously, pointing to the file specified by the file parameter.	FileStream
		propertyIsEnumerable(name:String):Boolean Indicates whether the specified property exists and is enumerable.	Object
		readBoolean():Boolean Reads a Boolean value from the file stream, byte stream, or byte array.	FileStream
		readByte():int Reads a signed byte from the file stream, byte stream, or byte array.	FileStream
		readBytes(bytes:ByteArray, offset:uint = 0, length:uint = 0):void Reads the number of data bytes, specified by the length parameter, from the file stream, byte stream, or byte array.	FileStream
		readDouble():Number Reads an IEEE 754 double-precision floating point number from the file stream, byte stream, or byte array.	FileStream
		readFloat():Number Reads an IEEE 754 single-precision floating point number from the file stream, byte stream, or byte array.	FileStream
		readInt():int Reads a signed 32-bit integer from the file stream, byte stream, or byte array.	FileStream
		readMultiByte(length:uint, charSet:String):String Reads a multibyte string of specified length from the file stream, byte stream, or byte array using the specified character set.	FileStream
		readObject():* Reads an object from the file stream, byte stream, or byte array, encoded in AMF serialized format.	FileStream
		readShort():int Reads a signed 16-bit integer from the file stream, byte stream, or byte array.	FileStream
		readUnsignedByte():uint Reads an unsigned byte from the file stream, byte stream, or byte array.	FileStream
		readUnsignedInt():uint Reads an unsigned 32-bit integer from the file stream, byte stream, or byte array.	FileStream
		readUnsignedShort():uint Reads an unsigned 16-bit integer from the file stream, byte stream, or byte array.	FileStream
		readUTF():String Reads a UTF-8 string from the file stream, byte stream, or byte array.	FileStream
		readUTFBytes(length:uint):String Reads a sequence of UTF-8 bytes from the byte stream or byte array and returns a string.	FileStream
		removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void Removes a listener from the EventDispatcher object.	EventDispatcher
		setPropertyIsEnumerable(name:String, isEnum:Boolean = true):void Sets the availability of a dynamic property for loop operations.	Object
		toLocaleString():String Returns the string representation of this object, formatted according to locale-specific conventions.	Object
		toString():String Returns the string representation of the specified object.	Object
		truncate():void Truncates the file at the position specified by the position property of the FileStream object.	FileStream
		valueOf():Object Returns the primitive value of the specified object.	Object
		willTrigger(type:String):Boolean Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type.	EventDispatcher
		writeBoolean(value:Boolean):void Writes a Boolean value.	FileStream
		writeByte(value:int):void Writes a byte.	FileStream
		writeBytes(bytes:ByteArray, offset:uint = 0, length:uint = 0):void Writes a sequence of bytes from the specified byte array, bytes, starting at the byte specified by offset (using a zero-based index) with a length specified by length, into the file stream, byte stream, or byte array.	FileStream
		writeDouble(value:Number):void Writes an IEEE 754 double-precision (64-bit) floating point number.	FileStream
		writeFloat(value:Number):void Writes an IEEE 754 single-precision (32-bit) floating point number.	FileStream
		writeInt(value:int):void Writes a 32-bit signed integer.	FileStream
		writeMultiByte(value:String, charSet:String):void Writes a multibyte string to the file stream, byte stream, or byte array, using the specified character set.	FileStream
		writeObject(object:*):void Writes an object to the file stream, byte stream, or byte array, in AMF serialized format.	FileStream
		writeShort(value:int):void Writes a 16-bit integer.	FileStream
		writeUnsignedInt(value:uint):void Writes a 32-bit unsigned integer.	FileStream
		writeUTF(value:String):void Writes a UTF-8 string to the file stream, byte stream, or byte array.	FileStream
		writeUTFBytes(value:String):void Writes a UTF-8 string.	FileStream

Events

Click for more information on events

Hide Inherited Events

Show Inherited Events

	Summary	Defined By
activate	[broadcast event] Dispatched when the Flash Player or AIR application gains operating system focus and becomes active.	EventDispatcher
close	Indicates that the stream has been closed by an explicit call to the close() method.	FileStream
complete	Signals that the end of the stream has been reached.	FileStream
deactivate	[broadcast event] Dispatched when the Flash Player or AIR application operating loses system focus and is becoming inactive.	EventDispatcher
ioError	Indicates that an error occurred during an asynchronous file I/O operation.	FileStream
outputProgress	Signals that buffered data has been written to the file.	FileStream
progress	Signals the availability of new data on the stream.	FileStream

Property Detail

bytesAvailable

property

bytesAvailable:uint [read-only]

Runtime Versions:

AIR 1.0

Returns the number of bytes of data available for reading in the input buffer. User code must call bytesAvailable to ensure that sufficient data is available before trying to read it with one of the read methods.

Implementation
public function get bytesAvailable():uint

endian

property

endian:String

Runtime Versions:

AIR 1.0

The byte order for the data, either the BIG_ENDIAN or LITTLE_ENDIAN constant from the Endian class.

Implementation
public function get endian():String
public function set endian(value:String):void

objectEncoding

property

objectEncoding:uint

Runtime Versions:

AIR 1.0

Specifies whether the AMF3 or AMF0 format is used when writing or reading binary data by using the readObject() or writeObject() method.

The value is a constant from the ObjectEncoding class. By default, the AMF3 format is used.

Implementation
public function get objectEncoding():uint
public function set objectEncoding(value:uint):void

Related API Elements

ObjectEncoding
readObject()
writeObject()

position

property

position:Number

Runtime Versions:

AIR 1.0

The current position in the file.

This value is modified in any of the following ways:

When you set the property explicitly
When reading from the FileStream object (by using one of the read methods)
When writing to the FileStream object

The position is defined as a Number (instead of uint) in order to support files larger than 2³² bytes in length. The value of this property is always a whole number less than 2⁵³. If you set this value to a number with a fractional component, the value is rounded down to the nearest integer.

When reading a file asyncronously, if you set the position property, the application begins filling the read buffer with the data starting at the specified position, and the bytesAvailable property may be set to 0. Wait for a complete event before using a read method to read data; or wait for a progress event and check the bytesAvailable property before using a read method.

Implementation
public function get position():Number
public function set position(value:Number):void

More examples

The position property of a FileStream object
The read buffer and the bytesAvailable property of a FileStream object

Example ( How to use this example )

The following code shows how a position property of the FileStream object is updated as the application reads data from a file.

Copy

import flash.fileSystem.*;
import flash.utils.ByteArray;
import flash.events.Event;

var sourceFile:File = File.documentsDirectory.resolvePath("Apollo Test/test.txt");
var stream:FileStream = new FileStream();
stream.addEventListener(Event.COMPLETE, readBytes);
stream.openAsync(sourceFile, FileMode.READ);

function readBytes(e:Event):void {
    var bytes:ByteArray = new ByteArray();
    trace("position 0:", stream.position); // 0
    bytes[0] = stream.readByte();
    trace("position 1:", stream.position); // 1
    fileStream.readBytes(bytes, stream.position, 4); 
    trace("position 2:", stream.position); // 5
    stream.close();
}

readAhead

property

readAhead:Number

Runtime Versions:

AIR 1.0

The minimum amount of data to read from disk when reading files asynchronously.

This property specifies how much data an asynchronous stream attempts to read beyond the current position. Data is read in blocks based on the file system page size. Thus if you set readAhead to 9,000 on a computer system with an 8KB (8192 byte) page size, the runtime reads ahead 2 blocks, or 16384 bytes at a time. The default value of this property is infinity: by default a file that is opened to read asynchronously reads as far as the end of the file.

Reading data from the read buffer does not change the value of the readAhead property. When you read data from the buffer, new data is read in to refill the read buffer.

The readAhead property has no effect on a file that is opened synchronously.

As data is read in asynchronously, the FileStream object dispatches progress events. In the event handler method for the progress event, check to see that the required number of bytes is available (by checking the bytesAvailable property), and then read the data from the read buffer by using a read method.

Implementation
public function get readAhead():Number
public function set readAhead(value:Number):void

Example ( How to use this example )

The following code shows how to use the readAhead property to limit the amount of data read into a file to 100 bytes:

Copy

import flash.filesystem.*;

var file:File = File.desktopDirectory.resolvePath("test.txt");
var fileStream:FileStream = new FileStream();
fileStream.readAhead = 100;
fileStream.addEventListener(ProgressEvent.PROGRESS, readProgressHandler)
fileStream.openAsync(file, FileMode.READ);
var results:ByteArray;

function readProgressHandler(event:ProgressEvent):void {
    if (fileStream.bytesAvailable >= 100) {
        fileStream.readBytes(results, 0, 100);
    }
}

Constructor Detail

()

Constructor

public function FileStream()

Runtime Versions:

AIR 1.0

Creates a FileStream object. Use the open() or openAsync() method to open a file.

Related API Elements

open()
openAsync()

Method Detail

close

()

method

public function close():void

Runtime Versions:

AIR 1.0

Closes the FileStream object.

You cannot read or write any data after you call the close() method. If the file was opened asynchronously (the FileStream object used the openAsync() method to open the file), calling the close() method causes the object to dispatch the close event.

Closing the application automatically closes all files associated with FileStream objects in the application. However, it is best to register for a closed event on all FileStream objects opened asynchronously that have pending data to write, before closing the application (to ensure that data is written).

You can reuse the FileStream object by calling the open() or the openAsync() method. This closes any file associated with the FileStream object, but the object does not dispatch the close event.

For a FileStream object opened asynchronously (by using the openAsync() method), even if you call the close() event for a FileStream object and delete properties and variables that reference the object, the FileStream object is not garbage collected as long as there are pending operations and event handlers are registered for their completion. In particular, an otherwise unreferenced FileStream object persists as long as any of the following are still possible:

For file reading operations, the end of the file has not been reached (and the complete event has not been dispatched).
Output data is still available to written, and output-related events (such as the outputProgress event or the ioError event) have registered event listeners.

Events

close:Event — The file, which was opened asynchronously, is closed.

Related API Elements

open()
close event

Example ( How to use this example )

The following code opens a FileStream object asynchronously and writes a text file named test.txt to the Apollo Test subdirectory of the user's documents directory. A call to the close() method of the FileStream object closes the file when the data is written.

Copy

import flash.filesystem.*;
import flash.events.Event;
            
var file:File = File.documentsDirectory;
file = file.resolvePath("Apollo Test/test.txt");
var fileStream:FileStream = new FileStream();
fileStream.openAsync(file, FileMode.WRITE);
fileStream.writeUTFBytes("Hello");
fileStream.addEventListener(Event.CLOSE, fileClosed);
fileStream.close();

function fileClosed(event:Event):void {
    trace("closed");
}

The following code opens a FileStream object synchronously and writes a text file named test.txt to the Apollo Test subdirectory of the user's documents directory. A call to the close() method of the FileStream object closes the file when the data is written.

Copy

import flash.filesystem.*;
            
var file:File = File.documentsDirectory;
file = file.resolvePath("Apollo Test/test.txt");
var fileStream:FileStream = new FileStream();
fileStream.open(file, FileMode.WRITE);
fileStream.writeUTF("Hello");
fileStream.close();

open

()

method

public function open(file:File, fileMode:String):void

Runtime Versions:

AIR 1.0

Opens the FileStream object synchronously, pointing to the file specified by the file parameter.

If the FileStream object is already open, calling the method closes the file before opening and no further events (including close) are delivered for the previously opened file.

On systems that support file locking, a file opened in "write" or "update" mode (FileMode.WRITE or FileMode.UPDATE) is not readable until it is closed.

Once you are done performing operations on the file, call the close() method of the FileStream object. Some operating systems limit the number of concurrently open files.

Parameters

	`file:File` — The File object specifying the file to open.

	`fileMode:String` — A string from the FileMode class that defines the capabilities of the FileStream, such as the ability to read from or write to the file.

Throws

	`IOError` — The file does not exist; you do not have adequate permissions to open the file; you are opening a file for read access, and you do not have read permissions; or you are opening a file for write access, and you do not have write permissions.

	`SecurityError` — The file location is in the application directory, and the `fileMode` parameter is set to "append", "update", or "write" mode.

More examples

Initializing a FileStream object, and opening and closing files
Example: Reading an XML file into an XML object
Example: Reading and writing data with random access

Related API Elements

close()
File
FileMode

Example ( How to use this example )

The following code shows how to synchronously open a test.txt file in the Apollo Test subdirectory of the user's documents directory and then read the file into a string, using the system character set as the text encoding.

Copy

import flash.filesystem.*;

var file:File = File.documentsDirectory;
file = file.resolvePath("Apollo Test/test.txt");
var fileStream:FileStream = new FileStream();
fileStream.open(file, FileMode.READ);
var str:String = fileStream.readMultiByte(file.size, File.systemCharset);
trace(str);
fileStream.close();

openAsync

()

method

public function openAsync(file:File, fileMode:String):void

Runtime Versions:

AIR 1.0

Opens the FileStream object asynchronously, pointing to the file specified by the file parameter.

If the FileStream object is already open, calling the method closes the file before opening and no further events (including close) are delivered for the previously opened file.

If the fileMode parameter is set to FileMode.READ or FileMode.UPDATE, AIR reads data into the input buffer as soon as the file is opened, and progress and open events are dispatched as the data is read to the input buffer.

On systems that support file locking, a file opened in "write" or "update" mode (FileMode.WRITE or FileMode.UPDATE) is not readable until it is closed.

Once you are done performing operations on the file, call the close() method of the FileStream object. Some operating systems limit the number of concurrently open files.

Parameters

	`file:File` — The File object specifying the file to open.

	`fileMode:String` — A string from the FileMode class that defines the capabilities of the FileStream, such as the ability to read from or write to the file.

Events

	`ioError:IOErrorEvent` — The file does not exist; you do not have adequate permissions to open the file; you are opening a file for read access, and you do not have read permissions; or you are opening a file for write access, and you do not have write permissions.

	`progress:ProgressEvent` — Dispatched as data is read to the input buffer. (The file must be opened with the `fileMode` parameter set to `FileMode.READ` or `FileMode.UPDATE`.)

	`complete:Event` — The file data has been read to the input buffer. (The file must be opened with the `fileMode` parameter set to `FileMode.READ` or `FileMode.UPDATE`.)

Throws

SecurityError — The file location is in the application directory, and the fileMode parameter is set to "append", "update", or "write" mode.

More examples

Asynchronous programming and the events generated by a FileStream object opened asynchronously

Related API Elements

close()
complete event
ioError event
progress event
FileMode

Example ( How to use this example )

The following code shows how to asynchronously open a test.txt file in the Apollo Test subdirectory of the user's documents directory and then read the file into a string, using the system character set as the text encoding.

Copy

import flash.filesystem.*;
import flash.events.Event;

var file:File = File.documentsDirectory;
file = file.resolvePath("Apollo Test/test.txt");
var fileStream:FileStream = new FileStream();
fileStream.addEventListener(Event.COMPLETE, fileCompleteHandler)
fileStream.openAsync(file, FileMode.READ);

function fileCompleteHandler(event:Event):void {
    var str:String = fileStream.readMultiByte(fileStream.bytesAvailable, File.systemCharset);
    trace(str);
    fileStream.close();
}

readBoolean

()

method

public function readBoolean():Boolean

Runtime Versions:

AIR 1.0

Reads a Boolean value from the file stream, byte stream, or byte array. A single byte is read and true is returned if the byte is nonzero, false otherwise.

Returns

Boolean — A Boolean value, true if the byte is nonzero, false otherwise.

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

readByte

()

method

public function readByte():int

Runtime Versions:

AIR 1.0

Reads a signed byte from the file stream, byte stream, or byte array.

Returns

int — The returned value is in the range -128 to 127.

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

readBytes

()

method

public function readBytes(bytes:ByteArray, offset:uint = 0, length:uint = 0):void

Runtime Versions:

AIR 1.0

Reads the number of data bytes, specified by the length parameter, from the file stream, byte stream, or byte array. The bytes are read into the ByteArray objected specified by the bytes parameter, starting at the position specified by offset.

Parameters

	`bytes:ByteArray` — The `ByteArray` object to read data into.

	`offset:uint` (default = `0`) — The offset into the `bytes` parameter at which data read should begin.

	`length:uint` (default = `0`) — The number of bytes to read. The default value of 0 causes all available data to be read.

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

More examples

The read buffer and the bytesAvailable property of a FileStream object

readDouble

()

method

public function readDouble():Number

Runtime Versions:

AIR 1.0

Reads an IEEE 754 double-precision floating point number from the file stream, byte stream, or byte array.

Returns

Number — An IEEE 754 double-precision floating point number.

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

readFloat

()

method

public function readFloat():Number

Runtime Versions:

AIR 1.0

Reads an IEEE 754 single-precision floating point number from the file stream, byte stream, or byte array.

Returns

Number — An IEEE 754 single-precision floating point number.

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

readInt

()

method

public function readInt():int

Runtime Versions:

AIR 1.0

Reads a signed 32-bit integer from the file stream, byte stream, or byte array.

Returns

int — The returned value is in the range -2147483648 to 2147483647.

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

readMultiByte

()

method

public function readMultiByte(length:uint, charSet:String):String

Runtime Versions:

AIR 1.0

Reads a multibyte string of specified length from the file stream, byte stream, or byte array using the specified character set.

Parameters

	`length:uint` — The number of bytes from the byte stream to read.

	`charSet:String` — The string denoting the character set to use to interpret the bytes. Possible character set strings include `"shift-jis"`, `"cn-gb"`, `"iso-8859-1"`, and others. For a complete list, see Supported Character Sets. Note: If the value for the `charSet` parameter is not recognized by the current system, then Adobe^® Flash^® Player or Adobe^® AIR^® uses the system's default code page as the character set. For example, a value for the `charSet` parameter, as in `myTest.readMultiByte(22, "iso-8859-01")`, that uses `01` instead of `1` might work on your development system, but not on another system. On the other system, Flash Player or the AIR runtime will use the system's default code page.

Returns

String — UTF-8 encoded string.

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

Related API Elements

File.systemCharset

readObject

()

method

public function readObject():*

Runtime Versions:

AIR 1.0

Reads an object from the file stream, byte stream, or byte array, encoded in AMF serialized format.

Returns

* — The deserialized object

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

Related API Elements

flash.net.registerClassAlias()

readShort

()

method

public function readShort():int

Runtime Versions:

AIR 1.0

Reads a signed 16-bit integer from the file stream, byte stream, or byte array.

Returns

int — The returned value is in the range -32768 to 32767.

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

readUnsignedByte

()

method

public function readUnsignedByte():uint

Runtime Versions:

AIR 1.0

Reads an unsigned byte from the file stream, byte stream, or byte array.

Returns

uint — The returned value is in the range 0 to 255.

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

readUnsignedInt

()

method

public function readUnsignedInt():uint

Runtime Versions:

AIR 1.0

Reads an unsigned 32-bit integer from the file stream, byte stream, or byte array.

Returns

uint — The returned value is in the range 0 to 4294967295.

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

readUnsignedShort

()

method

public function readUnsignedShort():uint

Runtime Versions:

AIR 1.0

Reads an unsigned 16-bit integer from the file stream, byte stream, or byte array.

Returns

uint — The returned value is in the range 0 to 65535.

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

readUTF

()

method

public function readUTF():String

Runtime Versions:

AIR 1.0

Reads a UTF-8 string from the file stream, byte stream, or byte array. The string is assumed to be prefixed with an unsigned short indicating the length in bytes.

This method is similar to the readUTF() method in the Java^® IDataInput interface.

Returns

String — A UTF-8 string produced by the byte representation of characters.

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

readUTFBytes

()

method

public function readUTFBytes(length:uint):String

Runtime Versions:

AIR 1.0

Reads a sequence of UTF-8 bytes from the byte stream or byte array and returns a string.

Parameters

length:uint — The number of bytes to read.

Returns

String — A UTF-8 string produced by the byte representation of characters of the specified length.

Events

ioError:IOErrorEvent — The file cannot be read or the file is not open. This event is dispatched only for files opened for asynchronous operations (by using the openAsync() method).

Throws

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with read capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be read (for example, because the file is missing).

	`EOFError` — The position specfied for reading data exceeds the number of bytes available (specified by the `bytesAvailable` property).

truncate

()

method

public function truncate():void

Runtime Versions:

AIR 1.0

Truncates the file at the position specified by the position property of the FileStream object.

Bytes from the position specified by the position property to the end of the file are deleted. The file must be open for writing.

Throws

IllegalOperationError — The file is not open for writing.

Related API Elements

position

Example ( How to use this example )

The following code synchronously opens a test.txt file in the Apollo Test subdirectory of the user's documents directory and then trims the file to 100 characters in length if it is longer than 100 characters.

Copy

import flash.filesystem.*;

var file:File = File.documentsDirectory;
file = file.resolvePath("Apollo Test/test.txt");
var fileStream:FileStream = new FileStream();
fileStream.open(file, FileMode.UPDATE);
if (file.size > 100) {
    fileStream.position = 100;
    fileStream.truncate();
}
fileStream.close();

The following code asynchronously opens a test.txt file in the Apollo Test subdirectory of the user's documents directory, and then trims the file to 100 characters in length if it is longer than 100 characters.

Copy

var file:File = File.documentsDirectory;
file = file.resolvePath("Apollo Test/test.txt");
var fileStream:FileStream = new FileStream();
fileStream.openAsync(file, FileMode.UPDATE);
trace("start", file.size)
if (file.size > 100) {
    fileStream.position = 100;
    fileStream.truncate();
}
fileStream.addEventListener(Event.CLOSE, fileClosed);
fileStream.close();
function fileClosed(event:Event):void {
    trace("closed", file.size); 
}

writeBoolean

()

method

public function writeBoolean(value:Boolean):void

Runtime Versions:

AIR 1.0

Writes a Boolean value. A single byte is written according to the value parameter, either 1 if true or 0 if false.

Parameters

value:Boolean — A Boolean value determining which byte is written. If the parameter is true, 1 is written; if false, 0 is written.

Events

ioError:IOErrorEvent — You cannot write to the file (for example, because the file is missing). This event is dispatched only for files that have been opened for asynchronous operations (by using the openAsync() method).

Throws

IOError — The file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the open() method), the file cannot be written (for example, because the file is missing).

writeByte

()

method

public function writeByte(value:int):void

Runtime Versions:

AIR 1.0

Writes a byte. The low 8 bits of the parameter are used; the high 24 bits are ignored.

Parameters

value:int — A byte value as an integer.

Events

Throws

writeBytes

()

method

public function writeBytes(bytes:ByteArray, offset:uint = 0, length:uint = 0):void

Runtime Versions:

AIR 1.0

Writes a sequence of bytes from the specified byte array, bytes, starting at the byte specified by offset (using a zero-based index) with a length specified by length, into the file stream, byte stream, or byte array.

If the length parameter is omitted, the default length of 0 is used and the entire buffer starting at offset is written. If the offset parameter is also omitted, the entire buffer is written.

If the offset or length parameter is out of range, they are clamped to the beginning and end of the bytes array.

Parameters

	`bytes:ByteArray` — The byte array to write.

	`offset:uint` (default = `0`) — A zero-based index specifying the position into the array to begin writing.

	`length:uint` (default = `0`) — An unsigned integer specifying how far into the buffer to write.

Events

Throws

writeDouble

()

method

public function writeDouble(value:Number):void

Runtime Versions:

AIR 1.0

Writes an IEEE 754 double-precision (64-bit) floating point number.

Parameters

value:Number — A double-precision (64-bit) floating point number.

Events

Throws

writeFloat

()

method

public function writeFloat(value:Number):void

Runtime Versions:

AIR 1.0

Writes an IEEE 754 single-precision (32-bit) floating point number.

Parameters

value:Number — A single-precision (32-bit) floating point number.

Events

Throws

writeInt

()

method

public function writeInt(value:int):void

Runtime Versions:

AIR 1.0

Writes a 32-bit signed integer.

Parameters

value:int — A byte value as a signed integer.

Events

Throws

writeMultiByte

()

method

public function writeMultiByte(value:String, charSet:String):void

Runtime Versions:

AIR 1.0

Writes a multibyte string to the file stream, byte stream, or byte array, using the specified character set.

Parameters

	`value:String` — The string value to be written.

	`charSet:String` — The string denoting the character set to use. Possible character set strings include `"shift-jis"`, `"cn-gb"`, `"iso-8859-1"`, and others. For a complete list, see Supported Character Sets.

Events

Throws

Related API Elements

File.systemCharset

writeObject

()

method

public function writeObject(object:*):void

Runtime Versions:

AIR 1.0

Writes an object to the file stream, byte stream, or byte array, in AMF serialized format.

Parameters

object:* — The object to be serialized.

Events

Throws

Related API Elements

flash.net.registerClassAlias()

writeShort

()

method

public function writeShort(value:int):void

Runtime Versions:

AIR 1.0

Writes a 16-bit integer. The low 16 bits of the parameter are used; the high 16 bits are ignored.

Parameters

value:int — A byte value as an integer.

Events

Throws

writeUnsignedInt

()

method

public function writeUnsignedInt(value:uint):void

Runtime Versions:

AIR 1.0

Writes a 32-bit unsigned integer.

Parameters

value:uint — A byte value as an unsigned integer.

Events

Throws

writeUTF

()

method

public function writeUTF(value:String):void

Runtime Versions:

AIR 1.0

Writes a UTF-8 string to the file stream, byte stream, or byte array. The length of the UTF-8 string in bytes is written first, as a 16-bit integer, followed by the bytes representing the characters of the string.

Parameters

value:String — The string value to be written.

Events

Throws

	`RangeError` — If the length of the string is larger than 65535.

	`IOError` — The file has not been opened; the file has been opened, but it was not opened with write capabilities; or for a file that has been opened for synchronous operations (by using the `open()` method), the file cannot be written (for example, because the file is missing).

writeUTFBytes

()

method

public function writeUTFBytes(value:String):void

Runtime Versions:

AIR 1.0

Writes a UTF-8 string. Similar to writeUTF(), but does not prefix the string with a 16-bit length word.

Parameters

value:String — The string value to be written.

Events

Throws

Event Detail

close

Event

Event Object Type: flash.events.Event
property Event.type = flash.events.Event.CLOSE

Runtime Versions:

AIR 1.0

Indicates that the stream has been closed by an explicit call to the close() method.

The Event.CLOSE constant defines the value of the type property of a close event object.

This event has the following properties:

Property	Value
`bubbles`	`false`
`cancelable`	`false`; there is no default behavior to cancel.
`currentTarget`	The object that is actively processing the Event object with an event listener.
`target`	The object whose connection has been closed.

Related API Elements

close()

complete

Event

Event Object Type: flash.events.Event
property Event.type = flash.events.Event.COMPLETE

Runtime Versions:

AIR 1.0

Signals that the end of the stream has been reached.

The Event.COMPLETE constant defines the value of the type property of a complete event object.

This event has the following properties:

Property	Value
`bubbles`	`false`
`cancelable`	`false`; there is no default behavior to cancel.
`currentTarget`	The object that is actively processing the Event object with an event listener.
`target`	The network object that has completed loading.

Related API Elements

position

ioError

Event

Event Object Type: flash.events.IOErrorEvent
property IOErrorEvent.type = flash.events.IOErrorEvent.IO_ERROR

Runtime Versions:

AIR 1.0

Indicates that an error occurred during an asynchronous file I/O operation.

Defines the value of the type property of an ioError event object.

This event has the following properties:

Property	Value
`bubbles`	`false`
`cancelable`	`false`; there is no default behavior to cancel.
`currentTarget`	The object that is actively processing the Event object with an event listener.
`errorID`	A reference number associated with the specific error (AIR only).
`target`	The network object experiencing the input/output error.
`text`	Text to be displayed as an error message.

outputProgress

Event

Event Object Type: flash.events.OutputProgressEvent
property OutputProgressEvent.type = flash.events.OutputProgressEvent.OUTPUT_PROGRESS

Runtime Versions:

AIR 1.0

Signals that buffered data has been written to the file.

Defines the value of the type property of an outputProgress event object.

This event has the following properties:

Property	Value
`bubbles`	`false`
`bytesPending`	The number of bytes remaining to be written at the time the listener processes the event.
`bytesTotal`	The total number of bytes that ultimately will be written if the write process succeeds.
`cancelable`	`false`; there is no default behavior to cancel.
`currentTarget`	The object that is actively processing the Event object with an event listener.
`target`	The FileStream object reporting progress.

progress

Event

Event Object Type: flash.events.ProgressEvent
property ProgressEvent.type = flash.events.ProgressEvent.PROGRESS

Runtime Versions:

AIR 1.0

Signals the availability of new data on the stream.

Defines the value of the type property of a progress event object.

This event has the following properties:

Property	Value
`bubbles`	`false`
`bytesLoaded`	The number of items or bytes loaded at the time the listener processes the event.
`bytesTotal`	The total number of items or bytes that ultimately will be loaded if the loading process succeeds.
`cancelable`	`false`; there is no default behavior to cancel.
`currentTarget`	The object that is actively processing the Event object with an event listener.
`target`	The object reporting progress.

flash.filesystem FileStream - AS3		Properties \| Properties \| Constructor \| Methods \| Global Constants \| Events \| Styles \| Skin Parts \| Skin States \| Effects \| Constants \| Global Functions \| Functions \| Interfaces \| Classes \| Examples

FileStream - AS3

Classes x

bytesAvailable

endian

objectEncoding

position

readAhead

FileStream

close

open

openAsync

readBoolean

readByte

readBytes

readDouble

readFloat

readInt

readMultiByte

readObject

readShort

readUnsignedByte

readUnsignedInt

readUnsignedShort

readUTF

readUTFBytes

truncate

writeBoolean

writeByte

writeBytes

writeDouble

writeFloat

writeInt

writeMultiByte

writeObject

writeShort

writeUnsignedInt

writeUTF

writeUTFBytes

close

complete

ioError

outputProgress

progress