https://blog.csdn.net/qq_43061290/article/details/104577391
```
//把保存數據序列化為json數據
ObjectMapper mapper=new ObjectMapper();
String josn = mapper.writeValueAsString(info);
//設置content-Type
response.setContentType("application/json;charset=utf-8");
//把json寫到前台頁面
response.getWriter().write(josn);
```
直接寫給前端不做任何處理
```
ObjectMapper mapper = new ObjectMapper();
response.setContentType("application/json;charset=utf-8");
mapper.writeValue(response.getOutputStream(),info);
```
寫給前端之前先把數據封裝到session中，一般用於登陸后在前端顯示用戶名