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
 2     @RequestMapping("/seleteOaOrder")
 3     @ResponseBody
 4     public Object seleteOaOrder(String param){//param = "小明";
 5         System.out.println("+++++++++++++++++param:"+param);
 6         if(param!=null){
 7             RequestEntity request = new RequestEntity();
 8             request.setUserName("0755pss001");
 9             request.setPwd("pss");
10             Map<String,String> map = new HashMap<String, String>();
11             map.put("applicant", param);
12             System.out.println("++++++++++++++++++转json之前的map对象："+map.toString());
13             ObjectMapper json = new ObjectMapper();
14             String params = null;
15             try {
16                 //把map对象转成json格式的String字符串
17                 params = json.writeValueAsString(map);
18                 System.out.println("++++++++++++++++++转成的json格式字符串："+params);
19             } catch (JsonGenerationException e) {
20                 // TODO Auto-generated catch block
21                 e.printStackTrace();
22             } catch (JsonMappingException e) {
23                 // TODO Auto-generated catch block
24                 e.printStackTrace();
25             } catch (IOException e) {
26                 // TODO Auto-generated catch block
27                 e.printStackTrace();
28             }
29             request.setParams(params);
30             ResponseEntity response = buyOrderService.seleteOaOrder(request);
31             return response.getResult();
32         }
33         return null;
34     }    

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。