如何在Dart/ flutter中映射和显示嵌套的JSON？

dependencies:
  flutter:
    sdk: flutter
  json_annotation: ^4.0.0

dev_dependencies:
  flutter_test:
    sdk: flutter
  json_serializable: ^4.1.0
  build_runner: ^2.1.0

{
  "name": "John Doe",
  "age": 30,
  "address": {
    "street": "123 Main St",
    "city": "New York"
  }
}

import 'package:json_annotation/json_annotation.dart';

part 'person.g.dart';

@JsonSerializable()
class Person {
  String name;
  int age;
  Address address;

  Person({this.name, this.age, this.address});

  factory Person.fromJson(Map<String, dynamic> json) => _$PersonFromJson(json);
  Map<String, dynamic> toJson() => _$PersonToJson(this);
}

@JsonSerializable()
class Address {
  String street;
  String city;

  Address({this.street, this.city});

  factory Address.fromJson(Map<String, dynamic> json) => _$AddressFromJson(json);
  Map<String, dynamic> toJson() => _$AddressToJson(this);
}

flutter pub run build_runner build

import 'dart:convert';

void main() {
  String jsonStr = '{"name":"John Doe","age":30,"address":{"street":"123 Main St","city":"New York"}}';
  
  Map<String, dynamic> json = jsonDecode(jsonStr);
  Person person = Person.fromJson(json);
  
  print(person.name); // 输出：John Doe
  print(person.address.city); // 输出：New York
  
  Map<String, dynamic> newJson = person.toJson();
  String newJsonStr = jsonEncode(newJson);
  
  print(newJsonStr); // 输出：{"name":"John Doe","age":30,"address":{"street":"123 Main St","city":"New York"}}
}