Selecting and Playing Sound and Video | 347The process of actually playing a video or sound file has been farmed out to classes
that take care of all the details. So the operation that plays the video or audio is
tucked away in another class, and all you need to do in the concrete classes is to
instantiate the respective classes and add the instances to a display list.
At this juncture, you need to be aware of the connection between the two opera-
tions. The order of the algorithm’s operations is still the same; however, both opera-
tions are linked by a common private string variable used to store the name of the
media. Notice that both concrete classes use theselectMedia( )andplayNow( )func-
tions, even though they’re used in different ways.
The Detail Classes
While the Template Method design pattern allows for details to be added to the
operations in the template method itself through the concrete subclasses, both the
video and audio operations are a bit more detailed. So rather than shoehorning them
into concrete classes, each has its own class. Of course, by doing so, you set up
classes that you can very likely use in other applications.
The class built for the video is fairly elaborate, and the one for the sound is quite sim-
ple. Open two new ActionScript files and save the code in Example 9-11 and
Example 9-12 using the caption names as the filenames. Be sure to save them in the
same directory as the others in the application.
Example 9-11. PlayVideo.as
package
{
import flash.display.Sprite;
import flash.media.Video;
import flash.events.NetStatusEvent;
import flash.net.NetConnection;
import flash.net.NetStream;
import flash.text.TextField;
public class PlayVideo extends Sprite
{
private var vidNow:Video;
private var durText:TextField;
public function PlayVideo(vid:String)
{
var nc:NetConnection=new NetConnection( );
nc.connect(null);
var ns:NetStream=new NetStream(nc);
vidNow=new Video( );
vidNow.attachNetStream(ns);
vid+=".flv";
ns.play(vid);
vidNow.x=((550/2)-(vidNow.width/2));
vidNow.y=50;