Flutter:为容器的边框颜色设置动画

import 'package:flutter/material.dart';

class AnimatedBorderColor extends StatefulWidget {
  @override
  _AnimatedBorderColorState createState() => _AnimatedBorderColorState();
}

class _AnimatedBorderColorState extends State<AnimatedBorderColor> with SingleTickerProviderStateMixin {
  AnimationController _controller;
  Animation<Color> _colorAnimation;

  @override
  void initState() {
    super.initState();
    
    _controller = AnimationController(
      duration: Duration(seconds: 1),
      vsync: this,
    );
    
    _colorAnimation = ColorTween(
      begin: Colors.blue,
      end: Colors.red,
    ).animate(_controller);
    
    _controller.repeat(reverse: true);
  }

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

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _colorAnimation,
      builder: (context, child) {
        return Container(
          width: 200,
          height: 200,
          decoration: BoxDecoration(
            border: Border.all(color: _colorAnimation.value),
          ),
        );
      },
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: Scaffold(
      body: Center(
        child: AnimatedBorderColor(),
      ),
    ),
  ));
}