MACROMEDIA FLASH MX 2004 - ACTIONSCRIPT - Page 180

180 Chapter 10: Working with External Data
Using the LoadVars class
You can use the LoadVars class instead of
loadVariables() to transfer variables between a SWF
file and a server. The LoadVars class lets you send all the variables in an object to a specified URL
and load all the variables at a specified URL into an object. The response from the server triggers
the
LoadVars.onLoad() method and sets variables in the target. You can use LoadVars to obtain
error information and progress indications and to stream the data while it downloads.
The LoadVars class is similar to the XML class; it uses the methods
load(), send(), and
sendAndLoad() to initiate communication with the server. The main difference between the
LoadVars and XML classes is that the LoadVars data is a property of the LoadVars object, rather
than an XML DOM (Document Object Model) tree stored in the XML object.
You must create a LoadVars object to call its methods. This object is a container to hold the
loaded data.
The following procedure shows how to use a LoadVars object to load variables from a text file and
display those variables in a text field.
To load data with the LoadVars object:
1 In a text editor such as Notepad or SimpleText, create a text file and add the following text to
the text file:
day=11&month=July&year=2003
2 Save the file as date.txt.
3 In Flash, create a document.
4 Create a dynamic text field on the Stage and give it the instance name date_txt.
5 Select Frame 1 in the Timeline and open the Actions panel (Window > Development Panels >
Actions) if it isn’t already open.
6 Enter the following code in the Actions panel:
var dateVars = new LoadVars();
dateVars.onLoad = function(ok) {
if (ok) {
date_txt.text = dateVars.day+"/"+dateVars.month+"/"+dateVars.year;
}
};
dateVars.load("date.txt");
This code loads the variables in data.txt (day, month, year), then formats and displays them in
the text field date_txt.
7 Save the document as dateReader.fla to the same directory that contains date.txt (the text file
you saved in step 3).
8 Select Control > Test Movie to test the document.
For more information, see the LoadVars class entry in Chapter 12, “ActionScript Dictionary,”
on page 205.