前言

使用Flutter&Dart已经快两个季度了，期间参与了Flutter插件的开发、Flutter Tools开发、Flutter热修复以及内部使用Flutter for Web等的实践。这里简单推荐下一个Flutter的Json和Bean的互转流程。

流程

Json2Dart

比如我们使用一言官网的开放API——语句接口，获取一个JSON。

{
  "id": 841,
  "hitokoto": "不论生死，好坏，对错；只要载入史册那就代表胜利——历史由胜者书写",
  "type": "f",
  "from": "网络",
  "from_who": null,
  "creator": "hitokoto",
  "creator_uid": 1775,
  "reviewer": 0,
  "uuid": "56827477-4c50-4eab-bfdc-e21c0f02a59f",
  "created_at": "1478787580"
}

拿到Json之后，我们可以使用Json_to_Dart这个工具，复制Json到左边的输入框，输入名称OneSentence，点击Generate Dart即可生成我们需要的Bean类。

OneSentence.dart

class OneSentence {
  int id;
  String hitokoto;
  String type;
  String from;
  Null fromWho;
  String creator;
  int creatorUid;
  int reviewer;
  String uuid;
  String createdAt;

  OneSentence(
      {this.id,
      this.hitokoto,
      this.type,
      this.from,
      this.fromWho,
      this.creator,
      this.creatorUid,
      this.reviewer,
      this.uuid,
      this.createdAt});

  OneSentence.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    hitokoto = json['hitokoto'];
    type = json['type'];
    from = json['from'];
    fromWho = json['from_who'];
    creator = json['creator'];
    creatorUid = json['creator_uid'];
    reviewer = json['reviewer'];
    uuid = json['uuid'];
    createdAt = json['created_at'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['id'] = this.id;
    data['hitokoto'] = this.hitokoto;
    data['type'] = this.type;
    data['from'] = this.from;
    data['from_who'] = this.fromWho;
    data['creator'] = this.creator;
    data['creator_uid'] = this.creatorUid;
    data['reviewer'] = this.reviewer;
    data['uuid'] = this.uuid;
    data['created_at'] = this.createdAt;
    return data;
  }
}

• 使用OneSentence.fromJson可以将Map转化为Bean对象。
• 使用oneSentence.toJson可以将Bean类转化Json。

使用OneSentence.fromJson可以将Map转化为Bean对象，那么怎么将Json字符串转化为Map呢？

import 'dart:convert';

Map userMap = json.decode(jsonString);

因此，Json字符串需要先用dart:convert库下的json.decode将字符串转化为Map，之后使用Bean.fromJson(Map)将Json转化为Bean对象；至于Bean转Json则直接调用Bean类的toJson方法即可。

附录

• flutter string 转 字典
• JSON to Dart