window.runtime propertywindow.runtime.flash.net.URLLoader
InheritanceURLLoader Inheritance EventDispatcher Inheritance Object
Runtime Versions: AIR 1.0, Flash Player 9

The URLLoader class downloads data from a URL as text, binary data, or URL-encoded variables. It is useful for downloading text files, XML, or other information to be used in a dynamic, data-driven application.

A URLLoader object downloads all of the data from a URL before making it available to code in the applications. It sends out notifications about the progress of the download, which you can monitor through the bytesLoaded and bytesTotal properties, as well as through dispatched events.

The value you pass for the url parameter must, by default, be in exactly the same domain. For example, a 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, place a cross-domain policy file on the server hosting the data. However, AIR application content in the application security domain can access content from any domain.

When you use this class and in AIR application content in security sandboxes other than then application security sandbox, consider the following security model:

However, in Adobe AIR, content in the application security sandbox (content installed with the AIR application) are not restricted by these security limitations.

For more information, see the following:

View the examples

See also

URLRequest
URLVariables
URLStream


Properties
 PropertyDefined By
  bytesLoaded : uint = 0
Indicates the number of bytes that have been loaded thus far during the load operation.
URLLoader
  bytesTotal : uint = 0
Indicates the total number of bytes in the downloaded data.
URLLoader
 Inheritedconstructor : Object
A reference to the class object or constructor function for a given object instance.
Object
  data : *
The data received from the load operation.
URLLoader
  dataFormat : String = "text"
Controls whether the downloaded data is received as text (URLLoaderDataFormat.TEXT), raw binary data (URLLoaderDataFormat.BINARY), or URL-encoded variables (URLLoaderDataFormat.VARIABLES).
URLLoader
 Inheritedprototype : Object
[static] A reference to the prototype object of a class or function object.
Object
Public Methods
 MethodDefined By
  
URLLoader(request:URLRequest = null)
Creates a URLLoader object.
URLLoader
  
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.
URLLoader
  
Closes the load operation in progress.
URLLoader
 Inherited
dispatchEvent(event:Event):Boolean
Dispatches an event into the event flow.
EventDispatcher
 Inherited
hasEventListener(type:String):Boolean
Checks whether the EventDispatcher object has any listeners registered for a specific type of event.
EventDispatcher
 Inherited
hasOwnProperty(name:String):Boolean
Indicates whether an object has a specified property defined.
Object
 Inherited
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
  
Sends and loads data from the specified URL.
URLLoader
 Inherited
propertyIsEnumerable(name:String):Boolean
Indicates whether the specified property exists and is enumerable.
Object
 Inherited
removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void
Removes a listener from the EventDispatcher object.
EventDispatcher
 Inherited
setPropertyIsEnumerable(name:String, isEnum:Boolean = true):void
Sets the availability of a dynamic property for loop operations.
Object
 Inherited
toString():String
Returns the string representation of the specified object.
Object
 Inherited
valueOf():Object
Returns the primitive value of the specified object.
Object
 Inherited
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
Events
 Event Summary Defined By
 InheritedDispatched when Flash Player or an AIR application gains operating system focus and becomes active.EventDispatcher
  Dispatched after all the received data is decoded and placed in the data property of the URLLoader object.URLLoader
 InheritedDispatched when Flash Player or an AIR application loses operating system focus and is becoming inactive.EventDispatcher
  Dispatched if a call to the load() method attempts to access data over HTTP, and Adobe AIR is able to detect and return the status code for the request.URLLoader
  Dispatched if a call to URLLoader.load() attempts to access data over HTTP.URLLoader
  Dispatched if a call to URLLoader.load() results in a fatal error that terminates the download.URLLoader
  Dispatched when the download operation commences following a call to the URLLoader.load() method.URLLoader
  Dispatched when data is received as the download operation progresses.URLLoader
  Dispatched if a call to URLLoader.load() attempts to load data from a server outside the security sandbox.URLLoader
Property Detail
bytesLoadedproperty
var bytesLoaded:uint = 0
Runtime Versions: AIR 1.0, Flash Player 9

Indicates the number of bytes that have been loaded thus far during the load operation.

bytesTotalproperty 
var bytesTotal:uint = 0
Runtime Versions: AIR 1.0, Flash Player 9

Indicates the total number of bytes in the downloaded data. This property contains 0 while the load operation is in progress and is populated when the operation is complete. Also, a missing Content-Length header will result in bytesTotal being indeterminate.

dataproperty 
var data:*
Runtime Versions: AIR 1.0, Flash Player 9

The data received from the load operation. This property is populated only when the load operation is complete. The format of the data depends on the setting of the dataFormat property:

If the dataFormat property is URLLoaderDataFormat.TEXT, the received data is a string containing the text of the loaded file.

If the dataFormat property is URLLoaderDataFormat.BINARY, the received data is a ByteArray object containing the raw binary data.

If the dataFormat property is URLLoaderDataFormat.VARIABLES, the received data is a URLVariables object containing the URL-encoded variables.

See also

dataFormatproperty 
var dataFormat:String = "text"
Runtime Versions: AIR 1.0, Flash Player 9

Controls whether the downloaded data is received as text (URLLoaderDataFormat.TEXT), raw binary data (URLLoaderDataFormat.BINARY), or URL-encoded variables (URLLoaderDataFormat.VARIABLES).

If the value of the dataFormat property is URLLoaderDataFormat.TEXT, the received data is a string containing the text of the loaded file.

If the value of the dataFormat property is URLLoaderDataFormat.BINARY, the received data is a ByteArray object containing the raw binary data.

If the value of the dataFormat property is URLLoaderDataFormat.VARIABLES, the received data is a URLVariables object containing the URL-encoded variables.

The default value is URLLoaderDataFormat.TEXT.

See also

Constructor Detail
URLLoader()Constructor
function URLLoader(request:URLRequest = null)
Runtime Versions: AIR 1.0, Flash Player 9

Creates a URLLoader object.

Parameters
request:URLRequest (default = null) — A URLRequest object specifying the URL to download. If this parameter is omitted, no load operation begins. If specified, the load operation begins immediately (see the load entry for more information).

See also

Method Detail
addEventListener()method
function addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void
Runtime Versions: AIR 1.0

Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event.

JavaScript code in the AIR runtime uses this method to register event listeners for events defined by the AIR APIs. For other JavaScript events (such as the onload event of the DOM body object), you can use standard event handling techniques, as you would for content running in the browser.

After you successfully register an event listener, you cannot change its priority through additional calls to addEventListener(). To change a listener's priority, you must first call removeListener(). Then you can register the listener again with the new priority level.

Keep in mind that after the listener is registered, subsequent calls to addEventListener() with a different type or useCapture value result in the creation of a separate listener registration.

If you no longer need an event listener, remove it by calling removeEventListener(), or memory problems could result. Objects with registered event listeners are not automatically removed from memory because the garbage collector does not remove objects that still have references.

Copying an EventDispatcher instance does not copy the event listeners attached to it. (If your newly created node needs an event listener, you must attach the listener after creating the node.) However, if you move an EventDispatcher instance, the event listeners attached to it move along with it.

Parameters

type:String — The type of event.
 
listener:Function — The listener function that processes the event. This function must accept an Event object as its only parameter and must return nothing .

The function can have any name.

 
useCapture:Boolean (default = false)This parameter applies to display objects in the ActionScript 3.0 display list architecture, used by SWF content.
 
priority:int (default = 0) — The priority level of the event listener. The priority is designated by a signed 32-bit integer. The higher the number, the higher the priority. All listeners with priority n are processed before listeners of priority n-1. If two or more listeners share the same priority, they are processed in the order in which they were added. The default priority is 0.
 
useWeakReference:Boolean (default = false) — Determines whether the reference to the listener is strong or weak. A strong reference (the default) prevents your listener from being garbage-collected. A weak reference does not.

Class-level member functions are not subject to garbage collection, so you can set useWeakReference to true for class-level member functions without subjecting them to garbage collection. If you set useWeakReference to true for a listener that is a nested inner function, the function will be garbage-collected and no longer persistent. If you create references to the inner function (save it in another variable) then it is not garbage-collected and stays persistent.

close()method 
function close():void
Runtime Versions: AIR 1.0, Flash Player 9

Closes the load operation in progress. Any load operation in progress is immediately terminated. If no URL is currently being streamed, an invalid stream error is thrown.

load()method 
function load(request:URLRequest):void
Runtime Versions: AIR 1.0, Flash Player 9

Sends and loads data from the specified URL. The data can be received as text, raw binary data, or URL-encoded variables, depending on the value you set for the dataFormat property. Note that the default value of the dataFormat property is text. If you want to send data to the specified URL, you can set the data property in the URLRequest object.

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.

By default, for AIR content not in the application security domain, the URL you load must be in exactly the same domain as the calling file. For example, a 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.

In AIR applications, content in the application security sandbox can load content from any domain.

When you use this method in content in security sandboxes other than then application security sandbox, consider the AIR security model:

When you use this class in AIR application content in security sandboxes other than then application security sandbox, consider the AIR security model:

For more information, see the following:

Parameters

request:URLRequest — A URLRequest object specifying the URL to download.


Events
complete:Event — Dispatched after data has loaded successfully.
 
httpStatus:HTTPStatusEvent — If access is over 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.
 
progress:ProgressEvent — Dispatched when data is received as the download operation progresses.
 
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.
 
open:Event — Dispatched when a load operation commences.
 
httpResponseStatus:HTTPStatusEvent — Dispatched if a call to the load() method attempts to access data over HTTP and Adobe AIR is able to detect and return the status code for the request.

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: 1) AIR 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. 2) AIR 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 files may not communicate with the Internet. This may be worked around by reclassifying this file as local-with-networking or trusted.
 
TypeError — The value of the request parameter or the URLRequest.url property of the URLRequest object passed are null.

See also

Event Detail
complete Event
Event Object Type: flash.events.Event
property Event.type = flash.events.Event.COMPLETE
Runtime Versions: AIR 1.0, Flash Player 9

Dispatched after all the received data is decoded and placed in the data property of the URLLoader object. The received data may be accessed once this event has been dispatched.

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

This event has the following properties:

PropertyValue
bubblesfalse
cancelablefalse; there is no default behavior to cancel.
currentTargetThe object that is actively processing the Event object with an event listener.
targetThe network object that has completed loading.

See also

httpResponseStatus Event  
Event Object Type: flash.events.HTTPStatusEvent
property HTTPStatusEvent.type = flash.events.HTTPStatusEvent.HTTP_RESPONSE_STATUS
Runtime Versions: AIR 1.0, AIR 1.0

Dispatched if a call to the load() method attempts to access data over HTTP, and Adobe AIR is able to detect and return the status code for the request.

Unlike the httpStatus event, the httpResponseStatus event is delivered before any response data. Also, the httpResponseStatus event includes values for the responseHeaders and responseURL properties (which are undefined for an httpStatus event. Note that the httpResponseStatus event (if any) will be sent before (and in addition to) any complete or error event.

The HTTPStatusEvent.HTTP_RESPONSE_STATUS constant defines the value of the type property of a httpResponseStatus event object.

This event has the following properties:

PropertyValue
bubblesfalse
cancelablefalse; there is no default behavior to cancel.
currentTargetThe object that is actively processing the Event object with an event listener.
responseURLThe URL from which the response was returned.
responseHeadersThe response headers that the response returned, as an array of URLRequestHeader objects.
statusThe HTTP status code returned by the server.
targetThe network object receiving an HTTP status code.

See also

httpStatus Event  
Event Object Type: flash.events.HTTPStatusEvent
property HTTPStatusEvent.type = flash.events.HTTPStatusEvent.HTTP_STATUS
Runtime Versions: AIR 1.0, Flash Player 9

Dispatched if a call to URLLoader.load() attempts to access data over HTTP. Note that the httpStatus event (if any) is sent before (and in addition to) any complete or error event.

The HTTPStatusEvent.HTTP_STATUS constant defines the value of the type property of a httpStatus event object.

This event has the following properties:

PropertyValue
bubblesfalse
cancelablefalse; there is no default behavior to cancel.
currentTargetThe object that is actively processing the Event object with an event listener.
statusThe HTTP status code returned by the server.
targetThe network object receiving an HTTP status code.

See also

ioError Event  
Event Object Type: flash.events.IOErrorEvent
property IOErrorEvent.type = flash.events.IOErrorEvent.IO_ERROR
Runtime Versions: AIR 1.0, Flash Player 9

Dispatched if a call to URLLoader.load() results in a fatal error that terminates the download.

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

This event has the following properties:

PropertyValue
bubblesfalse
cancelablefalse; there is no default behavior to cancel.
currentTargetThe object that is actively processing the Event object with an event listener.
errorIDA reference number associated with the specific error.
targetThe network object experiencing the input/output error.
textText to be displayed as an error message.

See also

open Event  
Event Object Type: flash.events.Event
property Event.type = flash.events.Event.OPEN
Runtime Versions: AIR 1.0, Flash Player 9

Dispatched when the download operation commences following a call to the URLLoader.load() method.

The Event.OPEN constant defines the value of the type property of an open event object.

This event has the following properties:

PropertyValue
bubblesfalse
cancelablefalse; there is no default behavior to cancel.
currentTargetThe object that is actively processing the Event object with an event listener.
targetThe network object that has opened a connection.

See also

progress Event  
Event Object Type: flash.events.ProgressEvent
property ProgressEvent.type = flash.events.ProgressEvent.PROGRESS
Runtime Versions: AIR 1.0, Flash Player 9

Dispatched when data is received as the download operation progresses.

Note that with a URLLoader object, it is not possible to access the data until it has been received completely. So, the progress event only serves as a notification of how far the download has progressed. To access the data before it's entirely downloaded, use a URLStream object.

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

This event has the following properties:

PropertyValue
bubblesfalse
bytesLoadedThe number of items or bytes loaded at the time the listener processes the event.
bytesTotalThe total number of items or bytes that ultimately will be loaded if the loading process succeeds.
cancelablefalse; there is no default behavior to cancel.
currentTargetThe object that is actively processing the Event object with an event listener.
targetThe object reporting progress.

See also

securityError Event  
Event Object Type: flash.events.SecurityErrorEvent
property SecurityErrorEvent.type = flash.events.SecurityErrorEvent.SECURITY_ERROR
Runtime Versions: AIR 1.0, Flash Player 9

Dispatched if a call to URLLoader.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:

PropertyValue
bubblesfalse
cancelablefalse; there is no default behavior to cancel.
currentTargetThe object that is actively processing the Event object with an event listener.
targetThe network object reporting the security error.
textText to be displayed as an error message.

See also

Examples
URLLoaderExample.as

The following example loads and displays the data found in a local text file. It also traces event handling information.

Note: To test this example:

  1. Add the AIRAliases.js file to the project directory.
  2. Put a file named urlLoaderExample.txt on your localhost HTTP server. That file should only contain the following line of text: answer=42&question=unknown
  3. Create an application descriptor file for the project, and test the project using ADL.

The example code does the following:

  1. The init() function creates a URLLoader instance named loader and a URLRequest instance named request, which contains the location and name of the file to be loaded.
  2. The loader object is passed to the configureListeners() method, which adds listeners for each of the supported URLLoader events.
  3. The request object is then passed to loader.load(), which loads the text file.
  4. When the URLLoader has finished loading the text file the Event.COMPLETE event fires, triggering the completeHandler() method. The completeHandler() method creates a URLVariables object from the text loaded from the file. The URLVariables object converts URL-encoded name/value pairs into properties to make it easier to manipulate the loaded data.

<html>
    <head>
      <script src="AIRAliases.js" />
      <script>
        function init() {
            var loader = new air.URLLoader();
            configureListeners(loader);

            var request = new air.URLRequest("urlLoaderExample.txt");
            try {
                loader.load(request);
            } catch (error) {
                air.trace("Unable to load requested document.");
            }
        }

        function configureListeners(dispatcher) {
            dispatcher.addEventListener(air.Event.COMPLETE, completeHandler);
            dispatcher.addEventListener(air.Event.OPEN, openHandler);
            dispatcher.addEventListener(air.ProgressEvent.PROGRESS, progressHandler);
            dispatcher.addEventListener(air.SecurityErrorEvent.SECURITY_ERROR, securityErrorHandler);
            dispatcher.addEventListener(air.HTTPStatusEvent.HTTP_STATUS, httpStatusHandler);
            dispatcher.addEventListener(air.IOErrorEvent.IO_ERROR, ioErrorHandler);
        }

        function completeHandler(event) {
            var loader = air.URLLoader(event.target);
            air.trace("completeHandler: " + loader.data);
    
            var vars = new air.URLVariables(loader.data);
            air.trace("The answer is " + vars.answer);
        }

        function openHandler(event) {
            air.trace("openHandler: " + event);
        }

        function progressHandler(event) {
            air.trace("progressHandler loaded:" + event.bytesLoaded + " total: " + event.bytesTotal);
        }

        function securityErrorHandler(event) {
            air.trace("securityErrorHandler: " + event);
        }

        function httpStatusHandler(event) {
            air.trace("httpStatusHandler: " + event);
        }

        function ioErrorHandler(event) {
            air.trace("ioErrorHandler: " + event);
        }
      </script>
    </head>
    <body onload='init()'>
    </body>
</html>