Flutter有无状态类与State及生命周期详细介绍

class LessComponent extends StatelessWidget {
  const LessComponent({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Container();
  }
}

class FulComponent extends StatefulWidget {
  const FulComponent({Key? key}) : super(key: key);
  @override
  _FulComponentState createState() => _FulComponentState();
}
class _FulComponentState extends State<FulComponent> {
  @override
  Widget build(BuildContext context) {
    return Container();
  }
}

class FulComponent extends StatefulWidget {
  const FulComponent({Key? key}) : super(key: key);
  @override
  _FulComponentState createState() => _FulComponentState();
}
class _FulComponentState extends State<FulComponent> {
  int count = 0;
  static const sum = 10;
  final nowDate = new DateTime.now();
  @override
  Widget build(BuildContext context) {
    return Container(
      child: Column(
        children: [
          Text('${sum}'),
          ElevatedButton.icon(
              onPressed: () {
                setState(() {
                  count++;
                });
              },
              icon: Icon(Icons.add), 
              label: Text('添加')
          )
        ],
      ),
    );
  }
}

class FulComponent extends StatefulWidget {
  const FulComponent({Key? key}) : super(key: key);
  @override
  _FulComponentState createState() => _FulComponentState();
}
class _FulComponentState extends State<FulComponent> {
  int count = 0;
  static const sum = 10;
  final nowDate = new DateTime.now();
  @override
  void initState() { // 初始化生命周期钩子
    super.initState();
    //初始化操作 在这里做
  }
  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    // 依赖发生变更时 执行
  }
  @override
  void reassemble() {
    super.reassemble();
    // 重新安装时执行，一般在调试的时候用，在发正式版本时 不会执行
  }
  @override
  void didUpdateWidget(covariant FulComponent oldWidget) {
    super.didUpdateWidget(oldWidget);
    // 组件发生变更时调用，当父组件有变动，子组件也会执行此方法
  }
  @override
  void deactivate() {
    super.deactivate();
    // 停用
  }
  @override
  void dispose() {
    super.dispose();
    // 销毁
  }
  @override
  Widget build(BuildContext context) {
    return Container(
      child: Column(
        children: [
          Text('${sum}'),
          ElevatedButton.icon(
              onPressed: () {
                setState(() {
                  count++;
                });
              },
              icon: Icon(Icons.add),
              label: Text('添加')
          )
        ],
      ),
    );
  }
}