JSON parse error: Cannot deserialize instance of `int` out of START_OBJECT token; nested exception is com.fasterxml.jackson.databind.exc

代码程序：

@PostMapping("selectById")
@ResponseBody
public Result selectById(@RequestBody int id) {
Result result =new Result();
List<User> list = userService.selectById(id);
if(list.size()==1){
result.setCode("000");
result.setMsg("success");
result.setData(list);
}else if(list.size()==0){
result.setCode("E01");
result.setMsg("输入的id找不到有效用户");
result.setData(null);
}else {
result.setCode("E02");
result.setMsg("输入的id找到大于1个有效用户");
result.setData(list);
}
return result;
}

请求内容：

POST http://localhost:8080/user/selectById

POST data:
{
"id":300
}

返回信息：

{
: "timestamp":"2019-02-08T14:05:17.430+0000",
: "status":400,
: "error":"Bad Request",
: "message":"JSON parse error: Cannot deserialize instance of `int` out of START_OBJECT token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `int` out of START_OBJECT token\n at [Source: (PushbackInputStream); line: 1, column: 1]",
: "path":"/user/selectById"
}

用的是post的方式，传的入参是int id， 不是一个对象。

需要改成对象，然后获取对象的id

@ApiOperation(value = "根据ID查询用户的信息")
@PostMapping("selectById")
@ResponseBody
public Result selectById(@RequestBody User user) {
Result result =new Result();
List<User> list = userService.selectById(user.getId());
if(list.size()==1){
result.setCode("000");
result.setMsg("success");
result.setData(list);
}else if(list.size()==0){
result.setCode("E01");
result.setMsg("输入的id找不到有效用户");
result.setData(null);
}else {
result.setCode("E02");
result.setMsg("输入的id找到大于1个有效用户");
result.setData(list);
}
return result;
}