list转json字符串

    @GetMapping("/valueTest")
public String valueTest() { 

List<Map<String,Object>> list = new ArrayList<>();
Map<String,Object> map1 = new HashMap<>();
map1.put("value",3339);
map1.put("name","联盟广告");
Map<String,Object> map2 = new HashMap<>();
map2.put("value",1000);
map2.put("name","test");
Map<String,Object> map3 = new HashMap<>();
map3.put("value",666);
map3.put("name","邮件营销");
list.add(map1);
list.add(map2);
list.add(map3);
Gson gson =new Gson();
String str = gson.toJson(list);
return str;
}

    String json = JSONArray.fromObject(list).toString();