Jackson -展开嵌套属性

public class User {
    private String name;
    private Address address;

    // Getter and Setter methods

    public static class Address {
        private String city;
        private String country;

        // Getter and Setter methods
    }
}

public class Main {
    public static void main(String[] args) throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();

        User.Address address = new User.Address();
        address.setCity("Beijing");
        address.setCountry("China");

        User user = new User();
        user.setName("John Doe");
        user.setAddress(address);

        String json = objectMapper.writeValueAsString(user);
        System.out.println(json);
    }
}

{
  "name" : "John Doe",
  "city" : "Beijing",
  "country" : "China"
}