apache的httpclient如何访问带两个参数的post接口

 @RequestMapping(value = "/webmail/message", method = RequestMethod.POST, produces = { MediaType.APPLICATION_JSON_VALUE})
    @ResponseBody
    public String sendWebmail(@RequestBody Message message, @RequestBody List<Affix> affixs) throws IOException {}

Message为实体，Affix也是实体
请问这种api接口，用apache的httpclient如何实现呢？

 client = new HttpClient();
            PostMethod method = new PostMethod(url);
            method.setParameter("Message",message);
            method.setParameter("Affix",affix);