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.

When loading very large video files, such as FLV's, out-of-memory errors may occur.

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

  • A SWF file in the local-with-filesystem sandbox may not load data from, or provide data to, a resource that is in the network sandbox.
  • By default, the calling SWF file and the URL you load must be in exactly the same domain. 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, place a URL policy file on the server hosting the data.

For more information related to security, see the Flash Player Developer Center Topic: Security.

@event complete 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.

@event httpResponseStatus 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.

@event httpStatus Dispatched if a call to URLLoader.load() attempts

                      to access data over HTTP. For content running in
                      Flash Player, this event is only dispatched if
                      the current Flash Player environment 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` event(if any) is sent
                      before(and in addition to) any
                      `complete` or `error`
                      event.

@event ioError Dispatched if a call to URLLoader.load() results

                      in a fatal error that terminates the download.

@event open Dispatched when the download operation commences

                      following a call to the
                      `URLLoader.load()` method.

@event progress 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. 

@event securityError Dispatched if a call to URLLoader.load() attempts

                      to load data from a server outside the security
                      sandbox. Also dispatched if a call to
                      `URLLoader.load()` attempts to load a
                      SWZ file and the certificate is invalid or the
                      digest string does not match the component.

Constructor

new (?request:URLRequest)

Creates a URLLoader object.

Parameters:

request

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).

Variables

bytesLoaded:Int

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

bytesTotal:Int

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.

data:Dynamic

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.

dataFormat:URLLoaderDataFormat

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.

Methods

close ():Void

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 (request:URLRequest):Void

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.

A SWF file in the local-with-filesystem sandbox may not load data from, or provide data to, a resource that is in the network sandbox.

By default, the calling SWF file and the URL you load must be in exactly the same domain. 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, place a URL policy file on the server hosting the data.

You cannot connect to commonly reserved ports. For a complete list of blocked ports, see "Restricting Networking APIs" in the ActionScript 3.0 Developer's Guide.

In Flash Player 10 and later, if you use a multipart Content-Type(for example "multipart/form-data") that contains an upload(indicated by a "filename" parameter in a "content-disposition" header within the POST body), the POST operation is subject to the security rules applied to uploads:

  • The POST operation must be performed in response to a user-initiated action, such as a mouse click or key press.
  • If the POST operation is cross-domain(the POST target is not on the same server as the SWF file that is sending the POST request), the target server must provide a URL policy file that permits cross-domain access.

Also, for any multipart Content-Type, the syntax must be valid (according to the RFC2046 standards). If the syntax appears to be invalid, the POST operation is subject to the security rules applied to uploads.

For more information related to security, see the Flash Player Developer Center Topic: Security.

@event complete Dispatched after data has loaded successfully. @event httpResponseStatus 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.

@event httpStatus 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.

@event ioError The load operation could not be completed. @event open Dispatched when a load operation commences. @event progress Dispatched when data is received as the download

                      operation progresses.

@event securityError 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.

@event securityError A load operation attempted to load a SWZ file(a

                      Adobe platform component), but the certificate
                      is invalid or the digest does not match the
                      component.

Parameters:

request

A URLRequest object specifying the URL to download.

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) Flash Player or 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) Flash Player or 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.

SecurityError

You are trying to connect to a commonly reserved port. For a complete list of blocked ports, see "Restricting Networking APIs" in the ActionScript 3.0 Developer's Guide.

TypeError

The value of the request parameter or the URLRequest.url property of the URLRequest object passed are null.

Inherited Variables

Inherited Methods

Defined by EventDispatcher

addEventListener (type:String, listener:Dynamic ‑> Void, useCapture:Bool = false, priority:Int = 0, useWeakReference:Bool = false):Void

Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event. You can register event listeners on all nodes in the display list for a specific type of event, phase, and priority.

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. For example, if you first register a listener with useCapture set to true, it listens only during the capture phase. If you call addEventListener() again using the same listener object, but with useCapture set to false, you have two separate listeners: one that listens during the capture phase and another that listens during the target and bubbling phases.

You cannot register an event listener for only the target phase or the bubbling phase. Those phases are coupled during registration because bubbling applies only to the ancestors of the target node.

If you no longer need an event listener, remove it by calling removeEventListener(), or memory problems could result. Event listeners are not automatically removed from memory because the garbage collector does not remove the listener as long as the dispatching object exists(unless the useWeakReference parameter is set to true).

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.

If the event listener is being registered on a node while an event is being processed on this node, the event listener is not triggered during the current phase but can be triggered during a later phase in the event flow, such as the bubbling phase.

If an event listener is removed from a node while an event is being processed on the node, it is still triggered by the current actions. After it is removed, the event listener is never invoked again(unless registered again for future processing).

Parameters:

type

The type of event.

useCapture

Determines whether the listener works in the capture phase or the target and bubbling phases. If useCapture is set to true, the listener processes the event only during the capture phase and not in the target or bubbling phase. If useCapture is false, the listener processes the event only during the target or bubbling phase. To listen for the event in all three phases, call addEventListener twice, once with useCapture set to true, then again with useCapture set to false.

priority

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

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.

Throws:

ArgumentError

The listener specified is not a function.

dispatchEvent (event:Event):Bool

Dispatches an event into the event flow. The event target is the EventDispatcher object upon which the dispatchEvent() method is called.

Parameters:

event

The Event object that is dispatched into the event flow. If the event is being redispatched, a clone of the event is created automatically. After an event is dispatched, its target property cannot be changed, so you must create a new copy of the event for redispatching to work.

Throws:

Error

The event dispatch recursion limit has been reached.

Returns:

A value of true if the event was successfully dispatched. A value of false indicates failure or that preventDefault() was called on the event.

hasEventListener (type:String):Bool

Checks whether the EventDispatcher object has any listeners registered for a specific type of event. This allows you to determine where an EventDispatcher object has altered handling of an event type in the event flow hierarchy. To determine whether a specific event type actually triggers an event listener, use willTrigger().

The difference between hasEventListener() and willTrigger() is that hasEventListener() examines only the object to which it belongs, whereas willTrigger() examines the entire event flow for the event specified by the type parameter.

When hasEventListener() is called from a LoaderInfo object, only the listeners that the caller can access are considered.

Parameters:

type

The type of event.

Returns:

A value of true if a listener of the specified type is registered; false otherwise.

removeEventListener (type:String, listener:Dynamic ‑> Void, useCapture:Bool = false):Void

Removes a listener from the EventDispatcher object. If there is no matching listener registered with the EventDispatcher object, a call to this method has no effect.

Parameters:

type

The type of event.

useCapture

Specifies whether the listener was registered for the capture phase or the target and bubbling phases. If the listener was registered for both the capture phase and the target and bubbling phases, two calls to removeEventListener() are required to remove both, one call with useCapture() set to true, and another call with useCapture() set to false.

toString ():String

willTrigger (type:String):Bool

Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type. This method returns true if an event listener is triggered during any phase of the event flow when an event of the specified type is dispatched to this EventDispatcher object or any of its descendants.

The difference between the hasEventListener() and the willTrigger() methods is that hasEventListener() examines only the object to which it belongs, whereas the willTrigger() method examines the entire event flow for the event specified by the type parameter.

When willTrigger() is called from a LoaderInfo object, only the listeners that the caller can access are considered.

Parameters:

type

The type of event.

Returns:

A value of true if a listener of the specified type will be triggered; false otherwise.