Understanding AS3 shared objects

This is the AS3 version of Managing savegames with Flash shared objects.

In this post I’ll explain the basic of shared objects, then later I’ll add the feature to Designing the structure of a Flash game – AS3 version in order to have a game template more complete.

Let’s start with the result: that’s what we are going to create:

As you will see, the counter increases when you reload the page.

Let’s take a look at the script:

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package {
	import flash.display.Sprite;
	import flash.net.SharedObject;
	import flash.text.*;
	public class as3_shared_objects extends Sprite {
		var shared:SharedObject;
		public function as3_shared_objects() {
			shared = SharedObject.getLocal("reloaded");
			if (shared.data.visits==undefined) {
				shared.data.visits = 1;
			}
			else {
				shared.data.visits ++;
			}
			show_text(shared.data.visits);
			shared.close();
		}
		public function show_text(str) {
			var shared_text:TextField = new TextField();
			var format:TextFormat = new TextFormat();
			format.font = "Lucida Console";
			format.color = 0xffff00;
			shared_text.width = 300;
			shared_text.defaultTextFormat = format;
			shared_text.x = 25;
			shared_text.y = 15;
			addChild(shared_text);
			shared_text.appendText("You visited this page "+str+" times");
		}
	}
}

Line 3: importing the class handling shared objects

Line 6: declaring a SharedObject variable called shared

Line 8: getLocal() returns a reference to a locally persistent shared object (in this case reloaded) that is available only to the current client. If the shared object does not already exist, getLocal() creates one.

Lines 9-11: when looking at the visits value inside the shared ojbect, I set it to 1 if it’s undefined (it’s the first time I am executing the script)

Lines 12-14: if visits is not undefined, it’s not the first time I am executing the script, so I have to increment its value

Line 16: closing the shared object. Some docs say you may experience problems if you don’t close it… I tried and I haven’t any… but I am closing it anyway…

Download the source code

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11 Responses

1. Orion says:

   December 28, 2008 at 9:00 pm

   So how to make something like ‘this site has been visited total of x times?

   Reply
2. Jack Hopkins says:

   December 29, 2008 at 7:40 pm

   you could use javascript, there are many scripts on the ‘net
   good tut!

   Reply
3. Pixelero says:

   January 2, 2009 at 1:58 pm

   Somehow if I update this by clicking on the headline ‘Understanding AS3 shared objects’ above, the counter increases by 2 ? – on a normal ‘F5′ browser update works correctly, and adds just 1.

   Reply
4. real reason says:

   January 4, 2009 at 1:02 pm

   To Orion: that isn’t the real reason he did this, it is there to show how u can have an update finished, for example: instead of updating each time u load it, it is updated each time that a level is finished, and it becomes the level number, not to show how many times u visit the page

   Reply
5. Designing the structure of a Flash game - AS3 version - Part 3 : Emanuele Feronato says:

   January 16, 2009 at 12:33 pm

   [...] Moreover, I made some code optimization and now you can only play levels you already completed and the first uncompleted level, thanks to AS3 shared objects. [...]

   Reply
6. Danny says:

   February 16, 2009 at 11:00 am

   Very good, but dude, please change your logo back to the old one.

   I know that you paid money for this one, but you have to take the loss on the chin!

   Great blog though :)

   Reply
7. Tutorial: Sharing shared objects between games/applications « the keg’o'grog blog says:

   June 6, 2009 at 5:47 pm

   [...] youself familiar with Saving and Loading in Flash by reading this tutorial or this tutorial. Thanks to Michael and Emanuele for this. You should also bookmark their blogs, these guys are [...]

   Reply
8. Flash for Thought « Interactive Design II says:

   October 14, 2009 at 5:21 am

   [...] http://www.emanueleferonato.com/2008/12/28/understanding-as3-shared-objects/ [...]

   Reply
9. Oct 22 Week 04 Make Up Class « Flash For Artists says:

   October 22, 2009 at 9:24 pm

   [...] http://www.emanueleferonato.com/2008/12/28/understanding-as3-shared-objects/ [...]

   Reply
10. Broxter says:

    January 14, 2010 at 4:40 pm

    Thanks a lot! Just what I was looking for.

    Reply
11. Complete Flash Sokoban game in less than 2KB - Emanuele Feronato says:

    May 19, 2010 at 3:54 pm

    [...] 10 levels * Tiles of different color and shape * Shared objects to save the games * Eye-candy effects (being only 2KB!!) to show completed levels and current level [...]

    Reply