Serializing File Reference Instances in Adobe AIR
In one of the projects I am working one with the Adobe AIR bus tour, I had a need to serialize instance of File class to the file system. Normally you can do this with File.writeObject(), but as the player serializer / de-serializer does not know about the File class, this would not work for me.
I came up with a simple solution that I wanted to share. Basically, you need to extend the File class and provide the meta data for it to tell the player how to serialize and de-serialize the class. This will then allow it to be serialized to the file system.
Here is the code:
<?xml version="1.0" encoding="utf-8"?>
<mx:WindowedApplication xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
<mx:Script>
<![CDATA[
import flash.filesystem.FileMode;
import flash.filesystem.FileStream;
import flash.filesystem.File;
private function onSerialize():void
{
//file reference to serialize
var f:MyFile = new MyFile("app-resource:/foo.txt");
//file that we will write serialized object to
var ser:File = new File("app-storage:/store.db");
var fs:FileStream = new FileStream();
fs.open(ser, FileMode.WRITE);
fs.writeObject(f);
fs.close();
}
private function onDeSerialize():void
{
var ser:File = new File("app-storage:/store.db");
var fs:FileStream = new FileStream();
fs.open(ser, FileMode.READ);
var f:MyFile = fs.readObject() as MyFile;
fs.close();
}
]]>
</mx:Script>
<mx:Button label="Serialize" left="10" top="10" click="onSerialize()"/>
<mx:Button label="De-Serialize" left="92" top="10" click="onDeSerialize()"/>
</mx:WindowedApplication>
and the MyFile.as class:
package
{
import flash.filesystem.File;
[RemoteClass(alias="MyFile")]
public class MyFile extends File
{
public function MyFile(path:String = null)
{
super(path);
}
}
}
The key line is the [RemoteClass(alias="MyFile")] which tells the player how to serialize the class.
Of course, this technique should work with any other built in class that you need to serialize.
