Flutter MVVMFlutter 的 Model-View-ViewModel 实现

一个 Flutter 的 MVVM(Model-View-ViewModel) 实现， 它使用基于属性 (property) 的数据绑定在视图模型 (ViewModel) 与视图 (View) 之间建立关联，并通过视图模型 (ViewModel) 驱动视图 (View) 变化。以此简化 Flutter 开发过程中繁重的状态管理与 widget 树控制。

import 'package:flutter/widgets.dart';
import 'package:mvvm/mvvm.dart';
import 'dart:async';

// define ViewModel
class Demo1ViewModel extends ViewModel {
  Demo1ViewModel() {
    // define bindable property
    property<String>("time", initial: "");
    // timer
    start();
  }

  start() {
      Timer.periodic(const Duration(seconds: 1), (_) {
        var now = DateTime.now();
        // call setValue
        setValue<String>("time", "${now.hour}:${now.minute}:${now.second}");
      });
  }
}

// define View
class Demo1 extends View<Demo1ViewModel> {
  Demo1() : super(Demo1ViewModel());

  @override
  Widget buildCore(BuildContext context) {
    return Container(
        margin: EdgeInsets.symmetric(vertical: 100),
        padding: EdgeInsets.all(40),

        // binding
        child: $.watchFor("time", 
            builder: $.builder1((t) => 
              Text("$t", textDirection: TextDirection.ltr))));
  }
}

// run
void main() => runApp(Demo1());