function buildAxis(){
    var ary=[];
    ary.push("00:00");
    var start = Date.UTC(2017,1,1,-8,0,0);
    for(var i=0;i<288;i++){
        start += 1000*60*5;//(5分钟的毫秒数)
        var _date=new Date(start);
        var  Hours=cal(_date.getHours());
        var Minutes=cal(_date.getMinutes());
        ary.push(Hours+":"+Minutes);
    }
    ary.pop();
    return ary;
}
function cal(o){
    if(o<10&&String(o).length==1){
        return "0"+o;
    }else{
        return o;
    }
}