json，之前只是了解了下，没太在意。今天，面试被人问到json。就再温习一遍。为什么要用，有哪些好处。这里就不说了。

json由{},[],””,：加字符串组成。基本格式是{“字符串”：”字符串”}，也可以像数组一样嵌套。

用到json主要有他的两个方法：decode 和 encode。decode是从服务器取得json，encode是从本地（也就是flash自身）发送给服务器。前者可以理解为解码，后者可以理解为编码。

贴出 AS:

package 
{
    import flash.display.Sprite;
    import flash.display.StageScaleMode;
    import flash.display.StageAlign;
    import flash.events.Event;
    import flash.net.URLLoader;
    import flash.net.URLRequest;
    import flash.net.URLRequestMethod;
    import flash.net.URLVariables;
    import flash.system.System;

    import flash.events.MouseEvent;
    import json.JSON;

    public class Main extends Sprite
    {
        private var sdSp:Sprite;
        private var jsUrl:String = "http://localhost:8080/study/json/json.php";
        private var bugua:Boolean = true;
        private var jsArr:Array = [];
        public function Main():void
        {
            stage.scaleMode = StageScaleMode.NO_BORDER;
            stage.align = StageAlign.TOP_LEFT;
            System.useCodePage = true;

            sdSp=new Sprite();
            sdSp.graphics.beginFill(0x0000ff,0.3);
            sdSp.graphics.drawRect(0,0,100,36);
            sdSp.graphics.endFill();
            sdSp.x = stage.stageWidth / 2 - sdSp.width / 2;
            sdSp.y = stage.stageHeight / 2 - sdSp.height / 2;
            addChild(sdSp);

            sdSp.buttonMode = true;
            sdSp.addEventListener(MouseEvent.CLICK,clickHandler);
        }

        private function clickHandler(e:MouseEvent)
        {
            if (bugua)
            {
                loadJson(jsUrl);
            }
            else
            {
                trace("你给我的全部");
                jsArr = [];
                jsArr = [{"date":"2012-11-17","sound":[{"name":"预谋","url":"01.mp3","path":"/mp3/"},{"name":"你Hold住了吗","url":"02.mp3","path":"/mp3/"}]}];
                sendJson(jsArr);
            }
            bugua = ! bugua;
        }


        private function loadJson(url:String)
        {
            var myLoader:URLLoader=new URLLoader();
            var myRequest:URLRequest=new URLRequest();
            myRequest.url = url;
            myLoader.addEventListener(Event.COMPLETE,getCompleteHandler);
            myLoader.load(myRequest);
        }

        private function getCompleteHandler(e:Event)
        {
            var jsonObj:Object = {};
            jsonObj = JSON.decode(URLLoader(e.target).data);
            for (var i in jsonObj)
            {
                trace(i+"_"+json[i]);
                for (var j in jsonObj[i])
                {
                    trace(i+"_"+j+"_"+jsonObj[i][j]);
                }
            }
        }

        private function sendJson(array:Array):void
        {
            var jsonString:String = JSON.encode(jsArr);
            var myLoader:URLLoader=new URLLoader();
            var myVariables:URLVariables=new URLVariables();
            myVariables.json = jsonString;
            var myRequest:URLRequest=new URLRequest();
            myRequest.data = myVariables;
            myRequest.method = URLRequestMethod.POST;
            myRequest.url = jsUrl;
            myLoader.addEventListener(Event.COMPLETE,sendCompleteHandler);
            myLoader.load(myRequest);
        }
        private function sendCompleteHandler(e:Event)
        {
            trace(e.target.data);
        }
    }

}