flutter json工廠模式

請求到的JSON：

{
    "a": "aa",
    "b": [
        {
            "ba": "b1111",
            "bb": "b2222"
        },
        {
            "ba": "b3333",
            "bb": "b4444"
        }
    ],
    "c": {
        "ca": "c111",
        "cb": "c222"
    }
}

對JSON進行工廠模式：

class NameModel {
  String a;
  List<B> b;
  C c;

  NameModel({this.a, this.b, this.c});

  NameModel.fromJson(Map<String, dynamic> json) {
    a = json['a'];
    if (json['b'] != null) {
      b = new List<B>();
      json['b'].forEach((v) {
        b.add(new B.fromJson(v));
      });
    }
    c = json['c'] != null ? new C.fromJson(json['c']) : null;
  }
	
  //返回完整數據就使用toJson方法
  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['a'] = this.a;
    if (this.b != null) {
      data['b'] = this.b.map((v) => v.toJson()).toList();
    }
    if (this.c != null) {
      data['c'] = this.c.toJson();
    }
    return data;
  }
}

class B {
  String ba;
  String bb;

  B({this.ba, this.bb});

  B.fromJson(Map<String, dynamic> json) {
    ba = json['ba'];
    bb = json['bb'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['ba'] = this.ba;
    data['bb'] = this.bb;
    return data;
  }
}

class C {
  String ca;
  String cb;

  C({this.ca, this.cb});

  C.fromJson(Map<String, dynamic> json) {
    ca = json['ca'];
    cb = json['cb'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['ca'] = this.ca;
    data['cb'] = this.cb;
    return data;
  }
}

使用工廠模式：

//1. 將請求到的數據解碼（snapshot.data是請求到的數據）
var data = json.decode(snapshot.data.toString());

//2. 將數據工廠化
NameModel dataName = NameModel.fromJson(data);

//3. 使用裏面需要的數據
setState(() {
  b = dataName.b
})