换种方式实现Ajax的异步传输

 ajax的跨域一直是一个问题，在网络上流行的几种解决方法外我有了自己的解决方法。

基本思路如下：

1，js向flash发请求

2，flash请求服务器端数据（因为flash的跨域只需要在目标服务器的根目录放一个xml，而不需要写代理）

3，flash取得数据后再回调js的方法，这样就完成了一次异步请求

另外在获取服务器端数据的过程中flash可以实时将已读取的字节数通知给js，这是xmlhttprequest做不到的，也就是能实现完美的loading（有个前提，就是服务器端的xml不能是动态生成，要不只能取得已读取的字节，而取不到总字节）；

as代码如下：

package ...{
    import flash.display.Sprite;
    import flash.events.*;
    import flash.net.*;
    import flash.xml.*;
    import flash.system.*;
    import flash.external.ExternalInterface;
    import flash.utils.Dictionary;
    import flash.text.TextField;
    import flash.utils.Timer;
    import flash.text.TextFieldType;
    import flash.text.TextFieldAutoSize;
    import NT.*;
    import flash.utils.*;
    public class AjaxHelper extends Sprite ...{

        private var config_url:Object=...{
        /**//*接口地址1*/
         soufun:...{url:"http://xxx?",handle:xml2Obj4sf},
         /**//*接口地址2*/
         mapabc:...{url:"http://xxx?",handle:xml2Obj4map},
         /**//*接口地址3*/
         ip:"XMLFile.xml"
         };
        private var err:String="";//错误
        public function errorOut():void ...{
            ExternalInterface.call("alert",err);
        }
        private var cstate:Boolean=false;//状态
        public function get cstateOut():Boolean ...{
            return this.cstate;
        }
        var t1:Date;
        var t2:Date;
        private var output:TextField;
        /**//*入口函数*/
        public function AjaxHelper() ...{
            flash.system.System.useCodePage=true;
            t1=new Date();
            initJsInterface();
            //trace(Core.NetConfig)
            
            cstate=true;
            
            /**//*Debug*/
            output = new TextField();
            output.y = 0;
            output.width = 400;
            output.height = 200;
            output.multiline = true;
            output.wordWrap = true;
            output.border = true;
            output.text = "Initializing... ";
            addChild(output);
            //jsInterfaceHandle("sf",null,null);


        }
        /**//*初始化外部接口*/
        private function initJsInterface():void ...{
            var _f:Array=[
              ["nt_AjaxData",jsInterfaceHandle],
              ["nt_ErrOut",errorOut],
              ["nt_GetComAreaStr",jsInterfaceHandle]
              ];
            if (ExternalInterface.available) ...{
                try ...{
                    with (ExternalInterface) ...{
                        for (var i in _f) ...{
                            addCallback(_f[i][0], _f[i][1]);
                        }
                    }
                } catch (error:SecurityError) ...{
                    err+="发生安全错误: " + error.message + " ";
                } catch (error:Error) ...{
                    err+="发生错误: " + error.message + " ";
                }
            } else ...{
                err+="容器不允许接口.";
            }
        }
        /**//*外部接口处理函数*/
        private function jsInterfaceHandle(options:Object) ...{
            
            if (options.type in config_url) ...{
                output.appendText(String(options.type)+"--type---"+options.callback);
                sendHttpRequest(options);
            } else ...{
            }
            //处理待写

        }
        /**//*发送请求*/
        private function sendHttpRequest(options:Object):void ...{
            URLLoader.prototype["options"]=new Object;
            var loader:URLLoader = new URLLoader();
            loader["options"]["type"]=options.type;
            loader["options"]["callback"]=options.callback;
            if(options.progressback)loader["options"]["progressback"]=options.progressback;
            if(options.progressback)loader["options"]["errback"]=options.errback;
            configureListeners(loader);
            var request:URLRequest = new URLRequest(config_url[options.type].url+(options.para?options.para:"")+"&"+new Date().getTime().toString());
            try ...{
                loader.load(request);
            } catch (error:Error) ...{
                err+="无法请求.";
            }
        }
        /**//*设置读取事件委托*/
        private function configureListeners(dispatcher:IEventDispatcher):void ...{
            var _e:Array=[
              [Event.COMPLETE,completeHandler],
              [Event.OPEN,openHandler],
              [ProgressEvent.PROGRESS,progressHandler],
              [SecurityErrorEvent.SECURITY_ERROR,securityErrorHandler],
              [HTTPStatusEvent.HTTP_STATUS,httpStatusHandler],
              [IOErrorEvent.IO_ERROR,ioErrorHandler]
              ];
            with (dispatcher) ...{
                for (var i in _e) ...{
                    addEventListener(_e[i][0], _e[i][1]);
                }
            }
        }
        /**//*数据读取事件委托处理函数*/
        private function completeHandler(event:Event):void ...{/**//*完成*/
            t2=new Date();
            var dd=t2.getTime()-t1.getTime();
            output.appendText(dd);
            trace("时间差："+dd);
            var loader:URLLoader = URLLoader(event.target);
            //trace(loader["options"]["type"]);
            var newxml:XML=new XML();
            try ...{
                newxml=XML(loader.data.toString().replace(""","“").replace("'","‘"));//.replace(/http:///g,"")
            } catch (error:Error) ...{
                newxml=XML(<root>数据格式错误</root>);
            }
            var retobj:String=config_url[loader["options"]["type"]]["handle"](newxml);
            //trace(retobj);
            //output.appendText(retobj.poi[0].x);
            ExternalInterface.call(loader["options"]["callback"].toString(),retobj);//回调
        }
        private function openHandler(event:Event):void ...{/**//*开始*/
            //output.appendText("openHandler: " + event);
        }

        private function progressHandler(event:ProgressEvent):void ...{/**//*过程*/
            var loader:URLLoader = URLLoader(event.target);
            if(loader["options"]["progressback"])
            ExternalInterface.call(loader["options"]["progressback"].toString(),event.bytesLoaded+"/"+event.bytesTotal);
        }

        private function securityErrorHandler(event:SecurityErrorEvent):void ...{/**//*安全错误*/
            err+="securityErrorHandler: " + event;
            var loader:URLLoader = URLLoader(event.target);
            if(loader["options"]["errback"])
            ExternalInterface.call(loader["options"]["errback"].toString(),err);
        }

        private function httpStatusHandler(event:HTTPStatusEvent):void ...{/**//*HTTP状态*/
            err+="httpStatusHandler: " + event;
        }

        private function ioErrorHandler(event:IOErrorEvent):void ...{/**//*IO错误*/
            err+="ioErrorHandler: " + event;
            var loader:URLLoader = URLLoader(event.target);
            if(loader["options"]["errback"])
            ExternalInterface.call(loader["options"]["errback"].toString(),err);
        }
        /**//*xml转换为Json*/
        protected function xml2Obj4sf(xml:XML):Object ...{/**//*sf*/
            var _str:String="{hit:[";
            for each (var element:XML in xml.hit) ...{
                _str+="{";
                var _t:String="";
                for each (var j in element.child("*")) ...{
                    _t+='"'+j.name()+'":"'+j+'",';
                }
                _t=_t.slice(0,_t.length-1);
                _str+=_t+"},";
            }
            if(xml.hit.length>0)
            _str=_str.slice(0,_str.length-1);
            _str+="]}";
            return _str;
        }
        protected function xml2Obj4map(xml:XML):Object ...{/**//*MAPABC*/
            var _str:String="{poi:[";
            for each (var element:XML in xml.list.poi) ...{
                _str+="{";
                var _t:String="";
                for each (var j in element.child("*")) ...{
                    _t+='"'+j.name()+'":"'+j+'",';
                }
                _t=_t.slice(0,_t.length-1);
                _str+=_t+"},";
            }
            if(xml.list.poi.length>0)
            _str=_str.slice(0,_str.length-1);
            _str+="]}";
            return _str;

        }
    }
}

使用as3写的，初步功能已经实现，具体效率还是有待实现

html的代码如下

 

<html>
 <head>
 <meta http-equiv="Content-Type" content="text/html; charset=gbk" />
 <title>AjaxHelper</title>
 <script language="JavaScript">...
    
     
     function thisMovie(movieName) ...{
         if (navigator.appName.indexOf("Microsoft") != -1) ...{
             return window[movieName];
         } else ...{
             return document[movieName];
         }
     }
     function sendToActionScript(value) ...{
        var _v=new Object();
        
        
         thisMovie("AjaxHelper").nt_AjaxData(_v);
     }
     function ascallback (jsonStr) ...{
        var kk=eval("("+jsonStr.toString()+")");
        thisMovie("AjaxHelper").nt_ErrOut();

        alert(kk.hit[0].title);
     } 

 </script>
 </head>
 <body>
 
     <object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000"
             id="AjaxHelper" width="400" height="200"
             codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab">
         <param name="movie" value="AjaxHelper.swf" />
         <param name="quality" value="high" />
         <param name="bgcolor" value="#869ca7" />
         <param name="allowScriptAccess" value="sameDomain" />
         <embed src="AjaxHelper.swf" quality="high" bgcolor="#869ca7"
             width="400" height="200" name="AjaxHelper" align="middle"
             play="true" loop="false" quality="high" allowScriptAccess="sameDomain"
             type="application/x-shockwave-flash"
             pluginspage="http://www.macromedia.com/go/getflashplayer">
         </embed>
     </object>
    <div id="outit"></div>
     <form name="form1" onsubmit="return false;">
         <input type="text" name="input" value="" />
         <input id="qq" type="button" value="Send" onclick="sendToActionScript(this.form.input.value);" /><br />
         
     </form>
 
 </body>
 </html>