在flutter中为小部件设置动画的正确方法是什么

AnimationController controller = AnimationController(
  duration: Duration(seconds: 1),
  vsync: this,
);

Animation<double> animation = Tween<double>(begin: 0, end: 1).animate(controller);

Opacity(
  opacity: animation.value,
  child: Container(
    // 小部件的内容
  ),
),

@override
void initState() {
  super.initState();
  controller.forward();
}

import 'package:flutter/material.dart';

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> with SingleTickerProviderStateMixin {
  AnimationController controller;
  Animation<double> animation;

  @override
  void initState() {
    super.initState();
    controller = AnimationController(
      duration: Duration(seconds: 1),
      vsync: this,
    );
    animation = Tween<double>(begin: 0, end: 1).animate(controller);
    controller.forward();
  }

  @override
  void dispose() {
    controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Opacity(
      opacity: animation.value,
      child: Container(
        // 小部件的内容
      ),
    );
  }
}