如何将@PathVariable注入到字段中？

@RestController
@RequestMapping("/users")
public class UserController {
    
    @GetMapping("/{id}")
    public User getUserById(@PathVariable("id") Long id) {
        // 根据id查询用户信息
        // ...
    }
}

@RestController
@RequestMapping("/users")
public class UserController {
    
    private Long userId;
    
    @GetMapping("/{id}")
    public User getUserById(@PathVariable("id") Long id) {
        this.userId = id; // 将PathVariable注入到字段中
        // 根据id查询用户信息
        // ...
    }
}