flutter json工厂模式

灰太狼 2023-02-23 03:53 86阅读 0赞

### 请求到的JSON： ###

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

### 对JSON进行工厂模式： ###

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;
      }
    	
      //返回完整数据就使用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;
      }
    }

### 使用工厂模式： ###

//1. 将请求到的数据解码（snapshot.data是请求到的数据）
    var data = json.decode(snapshot.data.toString());
    
    //2. 将数据工厂化
    NameModel dataName = NameModel.fromJson(data);
    
    //3. 使用里面需要的数据
    setState(() { 
      b = dataName.b
    })

## [JSON to Dart][] ##

[JSON to Dart]: https://javiercbk.github.io/json_to_dart/