Dart實體類格式

• 方案一：手寫實體類
• 方案二：生產力工具：網頁自動生成實體類
• 方案三：生產力工具：json_serializable使用技巧
  那個方案適合我？

Dart實體類格式

class CategoryMo {
  String name;
  int count;

  CategoryMo({this.name, this.count});
  //將map轉成mo
  CategoryMo.fromJson(Map<String, dynamic> json) {
    name = json['name'];
    count = json['count'];
  }
  //將mo轉成map，可缺省
  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['name'] = this.name;
    data['count'] = this.count;
    return data;
  }
}

手寫實體類

owner json

{
  "name": "伊零Onezero",
  "face": "http://i2.hdslb.com/bfs/face/1c57a17a7b077ccd19dba58a981a673799b85aef.jpg",
  "fans": 0
}

model轉換與使用

var ownerMap = {
  "name": "伊零Onezero",
  "face":
      "http://i2.hdslb.com/bfs/face/1c57a17a7b077ccd19dba58a981a673799b85aef.jpg",
  "fans": 0
};
Owner owner = Owner.fromJson(ownerMap);
print('name:${owner.name}');
print('fans:${owner.fans}');
print('face:${owner.face}');

網頁自動生成實體類

• 通過：https://www.devio.org/io/tools/json-to-dart/ 在線生成實體類

  {
    "id": "5633",
    "vid": "BV1q4411Y7zY",
    "title": "精神病人采訪實錄.突然覺得他們是那么的正?！?,
    "tname": "影視剪輯",
    "url": "https://o.devio.org/files/video/BV1yt4y1Q7SS.mp4",
    "cover": "http://i1.hdslb.com/bfs/archive/4d628fdc730243c78ad393fe1ab7d6a43ab7d0c7.jpg",
    "pubdate": 1557474141,
    "desc": "剪自《人間世》很棒的紀錄片，沒做好準備千萬別去看。",
    "view": 1333965,
    "duration": 145,
    "owner": {
      "name": "錦書致南辭",
      "face": "http://i0.hdslb.com/bfs/face/3f79d1df624218ab9a7774682fdb1d50a407ff88.jpg",
      "fans": 0
    },
    "reply": 2202,
    "favorite": 15392,
    "like": 36864,
    "coin": 3344,
    "share": 1841,
    "createTime": "2022-11-15 12:53:27",
    "size": 8161
  }

json_serializable使用技巧

• 官方demo：https://github.com/google/json_serializable.dart/tree/master/example

Step1：插件安裝

dependencies:
...
  dio: ^3.0.10
  json_annotation: ^3.1.0


dev_dependencies:
...
  json_serializable: ^3.5.0
  build_runner: ^1.0.0

Step2：配置實體類

對于下面的json使用json_serializable該如何配置呢？

{
    "code": 0,
    "method": "GET",
    "requestPrams": "dd"
}

import 'package:json_annotation/json_annotation.dart';

// result.g.dart 將在我們運行生成命令后自動生成
part 'result.g.dart';

///這個標注是告訴生成器，這個類是需要生成Model類的
@JsonSerializable()
class Result {
  //定義構造方法
  Result(this.code, this.method, this.requestPrams);
  //定義字段
  int code;
  String method;
  String requestPrams;

  //固定格式，不同的類使用不同的mixin即可
  factory Result.fromJson(Map<String, dynamic> json) => _$ResultFromJson(json);
  //固定格式
  Map<String, dynamic> toJson() => _$ResultToJson(this);
}

因為實體類的生成代碼還不存在，所以上代碼會提示一些錯誤是正常現(xiàn)象

Step3：執(zhí)行build生成實體類

flutter packages pub run build_runner build

那個方案適合我？