controller类中使用json返回错误码，实现用户登录

1、后台代码示例

@ResponseBody

@RequestMapping(value="login",method = RequestMethod.POST)

public User login(String username, String password, HttpServletRequest request,HttpServletResponse response) throws Exception{

try {

User user = userService.login(username, password);

if ( user != null) {

return user;

}else{

/*response.setCharacterEncoding("UTF-8"); */

response.setContentType("application/json; charset=utf-8");

response.getWriter().print("{\"code\":\"0\",\"msg\":\"密码错误\"}");

}

} catch (Exception e) {

// TODO: handle exception

}

return null;

}

2、前端ajax获取数据，并弹出错误码
$(".login").click(function(){

$.ajax({

type: "post",

url: "<%=path%>/test/login.do?username=lala&password=4534",

success: function (result) {

alert(result.id);

alert(result.code);

alert(result.msg);

}

});

});