Map对象转换成Json格式的String字符串

---

 1     //action处理页面发来的String，put到map转换成Json格式的String字符串
    @RequestMapping("/seleteOaOrder")
    @ResponseBody
    public Object seleteOaOrder(String param){//param = "小明";
        System.out.println("+++++++++++++++++param:"+param);
        if(param!=null){
            RequestEntity request = new RequestEntity();
            request.setUserName("0755pss001");
            request.setPwd("pss");
            Map<String,String> map = new HashMap<String, String>();
            map.put("applicant", param);
            System.out.println("++++++++++++++++++转json之前的map对象："+map.toString());
            ObjectMapper json = new ObjectMapper();
            String params = null;
            try {
                //把map对象转成json格式的String字符串
                params = json.writeValueAsString(map);
                System.out.println("++++++++++++++++++转成的json格式字符串："+params);
            } catch (JsonGenerationException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (JsonMappingException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            request.setParams(params);
            ResponseEntity response = buyOrderService.seleteOaOrder(request);
            return response.getResult();
        }
        return null;
    }    

---

后台打印的结果：
转json之前的map对象：{applicant:小明}
转成的json格式字符串：{"applicant":"小明"};
在new Map对象的时候可以写成Map<String,Integer> map = new HashMap<String, Integer>();
这里param是一个int，等于2，
转json之前的map对象：{applicant:2}
转成的json格式字符串：{"applicant":2};这里param不会有双引号。
主要是用ObjectMapper（
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;）
对map对象写成JSON格式的字符串。