为什么得不到后台传的JSON数据？

求帮助啊
Springmvc

    public void firstP(HttpServletRequest request) {
        List<Picture> pl = (List<Picture>) pageService.getPageList(1, number);
        JSONArray array = JSONArray.fromObject(pl);
        request.setAttribute("pl",array.toString());
        System.out.println(array.toString());
        request.setAttribute("user", "user");
    }

js：

能得到user,

<script>
        var pl = eval('('+"${pl}"+')');
        var u = "${user}";
        document.getElementById("show").innerHTML=pl[0].pid;
    </script>

后台打印的JSON:
[{"category":{"cid":2,"sort":"B"},"pdescribe":"BBB","pid":2,"pres":"333","psize":"bbb","purl":"bbb"},{"category":{"cid":3,"sort":"C"},"pdescribe":"ddd","pid":3,"pres":"333","psize":"ddd","purl":"ddd"},{"category":{"cid":1,"sort":"A"},"pdescribe":"eee","pid":4,"pres":"444","psize":"eee","purl":"eee"},{"category":{"cid":2,"sort":"B"},"pdescribe":"fff","pid":5,"pres":"fff","psize":"fff","purl":"ddd"}]

pl session存储对象序列化为json的字符串，而不是直接对象
http://www.docin.com/p-587238555.html
要不调用默认的toString得到的不是你那个字符串，你自己看客户端源代码就知道了

将${pl}用变量存起来，var pp = "${pl}";var pl = eval('('+pp+')');这样试试

可以看看 前阿泰选择接受的数据类型是什么样的