封装过的EXT的connection

function EucitaClient()
...{
    this._conn= new Ext.data.Connection();
    this.blocked=false;
    this.queue=new Array();
    var single=this;
    
    this.setCon=function(con)
    ...{
        if (con)
            this._conn=con;
    }
    
    this.commit=function(req)
    ...{
        if(single.blocked)
        ...{
            single.queue.push(req);
        }
        this.blocked=true;
        var reqWrapper=new Object();
        reqWrapper.callback=function(oElement, bSuccess, oResponse)
        ...{
            req.callback(oElement, bSuccess, oResponse);
            single.blocked=false;
            req=single.queue.pop();
            if(req)
                single.commit(req);
        }
        reqWrapper.url=req.url;
        reqWrapper.params=req.params;
        this._conn.request(reqWrapper);
    }
}
_conn=new EucitaClient();