| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
The URLStream class provides low-level access to
downloading URLs. Data is made available to ActionScript
immediately as it is downloaded, instead of waiting until
the entire file is complete as with URLLoader.
The URLStream class also lets you close a stream
before it finishes downloading.
The contents of the downloaded file are made available as raw binary data.
The read operations in URLStream are nonblocking.
This means that you must use the bytesAvailable property to determine
whether sufficient data is available before reading it. An
EOFError exception is thrown if insufficient
data is available.
All binary data is encoded by default in big-endian format, with the
most significant byte first.
The security rules that apply to URL downloading with the URLStream class are identical
to the rules applied to URLLoader objects.
Policy files may be downloaded as needed. Local file security rules are enforced,
and security warnings are raised as needed.
View the examples
bytesAvailable:uint [read-only]
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Returns the number of bytes of data available for reading
in the input buffer.
Your code must call the bytesAvailable property to ensure
that sufficient data is available before you try to read
it with one of the read methods.
Implementation
public function get bytesAvailable():uint
connected:Boolean [read-only]
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Indicates whether this URLStream object is
currently connected. A call to this property returns a value of true
if the URLStream object is connected, or false otherwise.
Implementation
public function get connected():Boolean
endian:String [read-write]
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Indicates the byte order for the data; possible values are
BIG_ENDIAN or LITTLE_ENDIAN.
The default value is Endian.BIG_ENDIAN.
Implementation
public function get endian():String
public function set endian(value:String):void
See also
objectEncoding:uint [read-write]
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Controls the version of Action Message Format (AMF) used when writing or reading an object.
Implementation
public function get objectEncoding():uint
public function set objectEncoding(value:uint):void
See also
public function close():void
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Immediately closes the stream and
cancels the download operation.
No data can be read from the stream after the close() method is called.
Throws
| IOError — The stream could not be closed, or the stream was not open.
|
public function load(request:URLRequest):void
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Begins downloading the URL specified in the request parameter.
Note: If a file being loaded contains non-ASCII characters
(as found in many non-English languages), it is recommended that you save the file
with UTF-8 or UTF-16 encoding, as opposed to a non-Unicode format like ASCII.
If the loading operation fails immediately, an IOError or SecurityError
(including the local file security error) exception is thrown describing the failure.
Otherwise, an open event is dispatched if the URL download
starts downloading successfully, or an error event is dispatched if an error occurs.
When using this method, consider the Adobe® Flash® Player security model:
- Data loading is not allowed if the calling SWF file is in the
local-with-file-system sandbox and the target resource is from a network sandbox.
- Data loading is also not allowed if the calling SWF file is from a network sandbox and
the target resource is local.
- By default, the URL you load must be in exactly the same domain as the calling SWF
file. For example, a SWF file at www.adobe.com can load data only from sources
that are also at www.adobe.com. To load data from a different domain, put a
cross-domain policy file on the server hosting the data.
- You can prevent a SWF file from using this method by setting the
allowNetworking parameter of the the object and embed
tags in the HTML page that contains the SWF content.
For more information, see the following:
Parameters
| request:URLRequest — A URLRequest object specifying the URL to download. If the value of
this parameter or the URLRequest.url property of the URLRequest object
passed are null, Flash Player throws a null pointer error.
|
Events
| complete:Event — Dispatched after data has loaded successfully. |
| |
| httpStatus:HTTPStatusEvent — If access is by HTTP, and the current
Flash Player environment supports obtaining status codes, you may
receive these events in addition to any complete
or error event. |
| |
| ioError:IOErrorEvent — The load operation could not be
completed. |
| |
| open:Event — Dispatched when a load operation starts. |
| |
| securityError:SecurityErrorEvent — A load operation attempted
to retrieve data from a server outside the caller's security sandbox.
This may be worked around using a policy file on the server. |
Throws
| ArgumentError — URLRequest.requestHeader objects may not contain
certain prohibited HTTP request headers. For more information, see the URLRequestHeader class
description.
|
| |
| MemoryError — This error can occur for the following reasons:- Flash Player
cannot convert the
URLRequest.data parameter from UTF8 to MBCS. This error is
applicable if the URLRequest object passed to load() is set to perform a GET operation
and if System.useCodePage is set to true. - Flash Player cannot allocate memory for
the
POST data. This error is applicable if the URLRequest object passed to load is set
to perform a POST operation.
|
| |
| SecurityError — Local untrusted SWF files may not communicate with
the Internet. This may be worked around by reclassifying this SWF file
as local-with-networking or trusted.
|
public function readBoolean():Boolean
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads a Boolean value from the stream. A single byte is read,
and true is returned if the byte is nonzero,
false otherwise.
Returns
| Boolean — True is returned if the byte is nonzero, false otherwise.
|
Throws
| EOFError — There is insufficient data available
to read. If a local SWF file triggers a security warning,
Flash Player prevents the URLStream data from being available to ActionScript.
When this happens, the bytesAvailable property returns 0 even if data has been
received, and any of the read methods throws an EOFError exception.
|
| |
| IOError — An I/O error occurred on the stream,
or the stream is not open.
|
public function readByte():int
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads a signed byte from the stream.
The returned value is in the range -128...127.
Returns
| int — Value in the range -128...127.
|
Throws
| EOFError — There is insufficient data available
to read. If a local SWF file triggers a security warning,
Flash Player prevents the URLStream data from being available to ActionScript.
When this happens, the bytesAvailable property returns 0 even if data has been
received, and any of the read methods throws an EOFError exception.
|
| |
| IOError — An I/O error occurred on the stream,
or the stream is not open.
|
public function readBytes(bytes:ByteArray, offset:uint = 0, length:uint = 0):void
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads length bytes of data from the stream.
The bytes are read into the ByteArray object specified
by bytes, starting offset bytes into
the ByteArray object.
Parameters
| bytes:ByteArray — The ByteArray object to read
data into.
|
| |
| offset:uint (default = 0) — The offset into bytes at which data
read should begin. Defaults to 0.
|
| |
| length:uint (default = 0) — The number of bytes to read. The default value
of 0 will cause all available data to be read.
|
Throws
| EOFError — There is insufficient data available
to read. If a local SWF file triggers a security warning,
Flash Player prevents the URLStream data from being available to ActionScript.
When this happens, the bytesAvailable property returns 0 even if data has been
received, and any of the read methods throws an EOFError exception.
|
| |
| IOError — An I/O error occurred on the stream,
or the stream is not open.
|
public function readDouble():Number
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads an IEEE 754 double-precision floating-point number from the stream.
Returns
| Number — An IEEE 754 double-precision floating-point number from the stream.
|
Throws
| EOFError — There is insufficient data available
to read. If a local SWF file triggers a security warning,
Flash Player prevents the URLStream data from being available to ActionScript.
When this happens, the bytesAvailable property returns 0 even if data has been
received, and any of the read methods throws an EOFError exception.
|
| |
| IOError — An I/O error occurred on the stream,
or the stream is not open.
|
public function readFloat():Number
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads an IEEE 754 single-precision floating-point number from the stream.
Returns
| Number — An IEEE 754 single-precision floating-point number from the stream.
|
Throws
| EOFError — There is insufficient data available
to read. If a local SWF file triggers a security warning,
Flash Player prevents the URLStream data from being available to ActionScript.
When this happens, the bytesAvailable property returns 0 even if data has been
received, and any of the read methods throws an EOFError exception.
|
| |
| IOError — An I/O error occurred on the stream,
or the stream is not open.
|
public function readInt():int
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads a signed 32-bit integer from the stream.
The returned value is in the range -2147483648...2147483647.
Returns
| int — Value in the range -2147483648...2147483647.
|
Throws
| EOFError — There is insufficient data available
to read. If a local SWF file triggers a security warning,
Flash Player prevents the URLStream data from being available to ActionScript.
When this happens, the bytesAvailable property returns 0 even if data has been
received, and any of the read methods throws an EOFError exception.
|
| |
| IOError — An I/O error occurred on the stream,
or the stream is not open.
|
public function readMultiByte(length:uint, charSet:String):String
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads a multibyte string of specified length from the byte stream 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 Flash Player 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 machine, but not on another machine. On the other machine, Flash Player will use the system's default code page.
|
Returns
| String — UTF-8 encoded string.
|
Throws
| EOFError — There is insufficient data available
to read.
|
public function readObject():*
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads an object from the socket, encoded in Action Message Format (AMF).
Returns
| * — The deserialized object.
|
Throws
| EOFError — There is insufficient data available
to read. If a local SWF file triggers a security warning,
Flash Player prevents the URLStream data from being available to ActionScript.
When this happens, the bytesAvailable property returns 0 even if data has been
received, and any of the read methods throws an EOFError exception.
|
| |
| IOError — An I/O error occurred on the stream,
or the stream is not open.
|
See also
public function readShort():int
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads a signed 16-bit integer from the stream.
The returned value is in the range -32768...32767.
Returns
| int — Value in the range -32768...32767.
|
Throws
| EOFError — There is insufficient data available
to read. If a local SWF file triggers a security warning,
Flash Player prevents the URLStream data from being available to ActionScript.
When this happens, the bytesAvailable property returns 0 even if data has been
received, and any of the read methods throws an EOFError exception.
|
| |
| IOError — An I/O error occurred on the stream,
or the stream is not open.
|
public function readUnsignedByte():uint
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads an unsigned byte from the stream.
The returned value is in the range 0...255.
Returns
| uint — Value in the range 0...255.
|
Throws
| EOFError — There is insufficient data available
to read. If a local SWF file triggers a security warning,
Flash Player prevents the URLStream data from being available to ActionScript.
When this happens, the bytesAvailable property returns 0 even if data has been
received, and any of the read methods throws an EOFError exception.
|
| |
| IOError — An I/O error occurred on the stream,
or the stream is not open.
|
public function readUnsignedInt():uint
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads an unsigned 32-bit integer from the stream.
The returned value is in the range 0...4294967295.
Returns
| uint — Value in the range 0...4294967295.
|
Throws
| EOFError — There is insufficient data available
to read. If a local SWF file triggers a security warning,
Flash Player prevents the URLStream data from being available to ActionScript.
When this happens, the bytesAvailable property returns 0 even if data has been
received, and any of the read methods throws an EOFError exception.
|
| |
| IOError — An I/O error occurred on the stream,
or the stream is not open.
|
public function readUnsignedShort():uint
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads an unsigned 16-bit integer from the stream.
The returned value is in the range 0...65535.
Returns
| uint — Value in the range 0...65535.
|
Throws
| EOFError — There is insufficient data available
to read. If a local SWF file triggers a security warning,
Flash Player prevents the URLStream data from being available to ActionScript.
When this happens, the bytesAvailable property returns 0 even if data has been
received, and any of the read methods throws an EOFError exception.
|
| |
| IOError — An I/O error occurred on the stream,
or the stream is not open.
|
public function readUTF():String
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads a UTF-8 string from the stream. The string
is assumed to be prefixed with an unsigned short indicating
the length in bytes.
Returns
Throws
| EOFError — There is insufficient data available
to read. If a local SWF file triggers a security warning,
Flash Player prevents the URLStream data from being available to ActionScript.
When this happens, the bytesAvailable property returns 0 even if data has been
received, and any of the read methods throws an EOFError exception.
|
| |
| IOError — An I/O error occurred on the stream,
or the stream is not open.
|
public function readUTFBytes(length:uint):String
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Reads a sequence of length UTF-8
bytes from the stream, and returns a string.
Parameters
| length:uint — A sequence of UTF-8 bytes.
|
Returns
| String — A UTF-8 string produced by the byte representation of characters of specified length.
|
Throws
| EOFError — There is insufficient data available
to read. If a local SWF file triggers a security warning,
Flash Player prevents the URLStream data from being available to ActionScript.
When this happens, the bytesAvailable property returns 0 even if data has been
received, and any of the read methods throws an EOFError exception.
|
| |
| IOError — An I/O error occurred on the stream,
or the stream is not open.
|
Event Object Type: flash.events.Event
Event.type property = flash.events.Event.COMPLETE
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Dispatched when data has loaded successfully.
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.
|
Event Object Type: flash.events.HTTPStatusEvent
HTTPStatusEvent.type property = flash.events.HTTPStatusEvent.HTTP_STATUS
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Dispatched if a call to URLStream.load()
attempts to access data over HTTP, and the current Flash Player
is able to detect and return the status code for the request. (Some browser environments
may not be able to provide this information.) Note that the httpStatus
(if any) will be sent before (and in addition to) any complete
or error event.
Defines the value of the
type property of a
httpStatus 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. |
status | The HTTP status code returned by the server. |
target | The network object receiving an HTTP status code. |
See also
Event Object Type: flash.events.IOErrorEvent
IOErrorEvent.type property = flash.events.IOErrorEvent.IO_ERROR
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Dispatched when an input/output error occurs that causes a load operation to fail.
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. |
target | The network object experiencing the input/output error. |
text | Text to be displayed as an error message. |
See also
Event Object Type: flash.events.Event
Event.type property = flash.events.Event.OPEN
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Dispatched when a load operation starts.
Defines the value of the
type property of an
open 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 opened a connection. |
See also
Event Object Type: flash.events.ProgressEvent
ProgressEvent.type property = flash.events.ProgressEvent.PROGRESS
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Dispatched when data is received as the download operation progresses.
Data that has been received can be read immediately using the methods of the URLStream class.
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 network object reporting progress. |
See also
Event Object Type: flash.events.SecurityErrorEvent
SecurityErrorEvent.type property = flash.events.SecurityErrorEvent.SECURITY_ERROR
| Language Version : | ActionScript 3.0 |
| Player Version : | Flash Player 9 |
Dispatched if a call to URLStream.load()
attempts to load data from a server outside the security sandbox.
The
SecurityErrorEvent.SECURITY_ERROR constant defines the value of the
type property of a
securityError 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 reporting the security error. |
text | Text to be displayed as an error message. |
See also
The following example loads a SWF file and parses the beginning of its header to indicate
compression and version number information.
To run the example, place a file named URLStreamExample.swf in the same directory as your SWF file.
package {
import flash.display.Sprite;
import flash.errors.*;
import flash.events.*;
import flash.net.URLRequest;
import flash.net.URLStream;
public class URLStreamExample extends Sprite {
private static const ZLIB_CODE:String = "CWS";
private var stream:URLStream;
public function URLStreamExample() {
stream = new URLStream();
var request:URLRequest = new URLRequest("URLStreamExample.swf");
configureListeners(stream);
try {
stream.load(request);
} catch (error:Error) {
trace("Unable to load requested URL.");
}
}
private function configureListeners(dispatcher:EventDispatcher):void {
dispatcher.addEventListener(Event.COMPLETE, completeHandler);
dispatcher.addEventListener(HTTPStatusEvent.HTTP_STATUS, httpStatusHandler);
dispatcher.addEventListener(IOErrorEvent.IO_ERROR, ioErrorHandler);
dispatcher.addEventListener(Event.OPEN, openHandler);
dispatcher.addEventListener(ProgressEvent.PROGRESS, progressHandler);
dispatcher.addEventListener(SecurityErrorEvent.SECURITY_ERROR, securityErrorHandler);
}
private function parseHeader():void {
trace("parseHeader");
trace("isCompressed: " + isCompressed());
trace("version: " + stream.readByte());
}
private function isCompressed():Boolean {
return (stream.readUTFBytes(3) == ZLIB_CODE);
}
private function completeHandler(event:Event):void {
trace("completeHandler: " + event);
parseHeader();
}
private function openHandler(event:Event):void {
trace("openHandler: " + event);
}
private function progressHandler(event:Event):void {
trace("progressHandler: " + event);
}
private function securityErrorHandler(event:SecurityErrorEvent):void {
trace("securityErrorHandler: " + event);
}
private function httpStatusHandler(event:HTTPStatusEvent):void {
trace("httpStatusHandler: " + event);
}
private function ioErrorHandler(event:IOErrorEvent):void {
trace("ioErrorHandler: " + event);
}
}
}
© 2004-2007 Adobe Systems Incorporated. All rights reserved.
Mon Nov 19 2007, 10:27 AM GMT-08:00