easyUi在后台加载异步树

public List<Dept> tree(String hql, String par) {

        Session session = getHibernateTemplate().getSessionFactory()
                .getCurrentSession();
        List list = new ArrayList();
        if (par.length() == 0) {
            list = session.createQuery(hql).list();
        } else {

            list = session.createQuery(hql).setString(0, par).list();
        }
        return list;
    }

public     List<Dept> tree(Dept dept) {
        String hql = "";
        String par = "";
        if (dept.getId()==null || dept.getId().trim().equals("")) {
            hql ="from Dept d where d.dept is null";
        }else{
            hql = "from Dept d where d.dept.id = ?";
            par = dept.getId();
        }
        
        return deptDao.tree(hql, par);
    }

//添加里面的树
    public String comboxtree() throws Exception {
        List<Dept> findAll = deptService.tree(dept);
        List list = new ArrayList();
        for (Dept dept : findAll) {
            Map map = new HashMap();
            if(dept.getDept() == null){
                map.put("id", dept.getId());
                map.put("text", dept.getName());
                map.put("pid", 0);
                map.put("state", "closed");
                list.add(map);
            }else{
                map.put("id", dept.getId());
                map.put("text", dept.getName());
                map.put("pid", dept.getDept().getId());
                List<Dept> depts = deptService.tree(dept);
                if(depts.size()>0){
                    map.put("state", "closed");
                }
                list.add(map);
                
            }
        }
        System.out.println(JSONArray.fromObject(list).toString());
        System.out.println();
        ServletActionContext.getResponse().getWriter().write(JSONArray.fromObject(list).toString());
        return null;
    }