struts2 ajax的一种实现方式

    /**
     * ajax请求，通过省份id获取学习中心
     */
    public void getSitesByPid() {
        HttpServletResponse response = ServletActionContext.getResponse();
        PrintWriter out = null;
        try {
            out = response.getWriter();
            List<PeSite> sites = presignService.getPeSites(pid);
            JSONArray json = JSONArray.fromObject(sites);
            out.print(json);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            out.flush();
            out.close();
        }
    }