how can build a txt document and write in flex application?

how can build a txt document and write in flex appl开发者_JAVA技巧ication ?

// in an init type method
var fileRef:FileReference = new FileReference();
var text:String = "Some text I want to save";
// continue building the text String variable as desired

// in some method that responds to a user event (NOT a system event):
fileRef.save(text, "defaultFileName.txt");

This may require that the user has Flash Player 10.