DecoratedBox控件会在子控件绘制之前或之后绘制一个装饰。

import 'package:flutter/material.dart';
class LayoutDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text('装饰容器'),),body: new DecoratedBox(
        decoration: new BoxDecoration(
          gradient: new LinearGradient(
            begin: const FractionalOffset(0.0,0.0),end: const FractionalOffset(1.0,1.0),colors: <Color>[const Color(0xffff2cc),const Color(0xffff6eb4)],)
        ),child: new Container(
          width: 250.0,height: 250.0,);
  }
}
void main() {
  runApp(
    new MaterialApp(
      title: 'Flutter教程',home: new LayoutDemo(),);
}