jquery异步请求回到json数据类型

jquery异步请求返回json数据类型
JSP页面：

 $.get("/kcm/common/tree2getChild/",                                {"id":id},                                function(data){                                    var html = makeHtml(data);                                    //回调函数                                },                         "json"); function makeHtml(data) {            var str="";            for(var i=0; i<data.length; i++) {                var html="";                var par=data[i].pId;                var hasChild = data[i].hasChild;                //alert(hasChild);                                html= "<tr id = '" + data[i].id +"'";                //not root                if(par != 0) {                    html = html + " pId='" + par +"'";                }                if (hasChild != 0) {                    html = html + " hasChild='true' ";                }                html = html + "><td></td><td>" + data[i].name +"</td></tr>";                                str += html;            }            //alert(str);            return str;         }

    @Execute(validator = false)    public String index() {        String id = request.getParameter("id");        try {            if (id == null) {                String strJson;                strJson = JSONUtil.fromList(getRootList());                wirteToResponse(response, strJson);            } else {                String strJson = JSONUtil.fromList(getChildList(id));                wirteToResponse(response, strJson);            }        } catch (Throwable e) {            e.printStackTrace();        }        return null;    }    public void wirteToResponse(HttpServletResponse response, String jsonObj) {        PrintWriter out = null;        response.setContentType("text/html;charset=utf-8");        try {            out = response.getWriter();            out.print(jsonObj);            out.flush();        } catch (IOException e) {            e.printStackTrace();        } finally {            out.close();        }    }