PHP 防止或检测页面被刷新 post重复提交问题

在解决post重复提交问题时,经过测试.没办法通过php检测是否被刷新.一般是通过js还判断

<script type="text/javascript">if (performance.navigation.type == 1){
alert(1);
window.location.href='?s=/Home/Index/user_order.html';
}else{
alert(0);
}
</script>

但都没法禁止post页面被重复提交
其实最好的办法是用ajax来提交表单,这样的话,只有点击提交按钮,表单才会提交.也就没必要检测刷新问题了.
比如在用户填写收货人的页面,就收集用户的post信息,通过ajax在后台提交订单.代码演示

按钮

<form action="" method="post" id="tijiao">
              <input type="hidden" name="cid" id="cid" value="{$cid}">
              <input type="hidden" name="num" id="num" value="{$num}">
              ......
              </form>
<div class="qr-btn1" onclick="jiao()">提交订单</div>

ajax代码

      function jiao(){
		   var s_xingming = $("[name='s_xingming']").val();
            var s_address = $("[name='s_address']").val();
            var s_email = $("[name='s_email']").val();
            var s_tel = $("[name='s_tel']").val();
			var zid = $('#zid').val();
            var wid = $('#wid').val();
            var cid = $("[name='cid']").val();
            var num = $("[name='num']").val();
		   var beizhu = $("[name='beizhu']").val();
            if("{$_SESSION['dluser']['s_xingming']}"==''){
              alert('请设置收货人姓名！');
              return;
            }
            if("{$_SESSION['dluser']['s_email']}"==''){
              alert('请设置收货人邮箱！');
              return;
            }
           if("{$_SESSION['dluser']['s_address']}"==''){
              alert('请设置收货人详细地址！');
              return;}
           if("{$_SESSION['dluser']['s_tel']}"==''){
              alert('请设置收货人手机！');
              return;
            }
            if($('#zid').val()==''){
              alert('请选择支付方式！');
              return;
            }
            if($('#wid').val()==''){
              alert('请选择配送方式！');
              return;
            }
            var lis="{$list[0]['cid']}";
            if(lis==''){
              alert('无商品！');
              return;
            }
     $.ajax({
              url:'/?a=user_buy_ajax',
              type:"post",
              data:"s_xingming="+s_xingming+"&s_address="+s_address+"&s_email="+s_email+"&s_tel="+s_tel+"&num="+num+"&zid="+zid+"&wid="+wid+"&cid="+cid+"&beizhu="+beizhu,
              success:function(re){
                if(re=="2"){
                  alert('失败');
                }else if(re=="3"){
                  alert('请先登录');
				  window.location.href='?a=dl';
                }else{
                 window.location.href='?a=user_buyc&id='+re;//ID传到付款二维码页面
                }
              }
            })
            //$('#tijiao').submit();
          }

PHP代码

	//ajax
	    function user_buy_ajax(){
		  if($_SESSION['dluser']['name']==''){
           echo 3;exit;
        }
        $uid=$_SESSION['dluser']['id'];
        $_POST['ctime']=time();
        $_POST['uid']=$uid;
	//	print_r( $_POST);exit;
        $id=M('order')->add($_POST);
	
	
        //添加商品
        $arr['uid']=$uid;
        $arr['oid']=$id;
        if(I('cid')){
            $arr['cid']=I('cid');
            $arr['num']=I('num');
            $map['allprice']=getzd(I('cid'),'contlist','price')*I('num');
            M('order_list')->add($arr);
        }else{
            $list=M('cart')->where('uid='.$uid)->select();
            $allprice=0;
            foreach ($list as $k => $v) {
                $arr['cid']=$v['cid'];
                $arr['guige']=$v['guige'];
                $arr['num']=$v['num'];
                $map['allprice']+=getzd($v['cid'],'contlist','price')*$v['num'];
                M('order_list')->add($arr);
            }
            M('cart')->where('uid='.$uid)->delete();
        }
        $code=$_POST['ctime'].$id;
        $map['code']=$code;
        $is2=M('order')->where('id='.$id)->save($map);
		if($is2){
           echo $id;exit;
        }else{
			echo 2;
		}
    }