如何在flutter应用中进行相关布局

Column(
  children: <Widget>[
    Text('子组件1'),
    Text('子组件2'),
    Text('子组件3'),
  ],
)

Row(
  children: <Widget>[
    Text('子组件1'),
    Text('子组件2'),
    Text('子组件3'),
  ],
)

Stack(
  children: <Widget>[
    Container(
      width: 200,
      height: 200,
      color: Colors.red,
    ),
    Container(
      width: 150,
      height: 150,
      color: Colors.green,
    ),
    Container(
      width: 100,
      height: 100,
      color: Colors.blue,
    ),
  ],
)

Flex(
  direction: Axis.horizontal,
  children: <Widget>[
    Expanded(
      flex: 1,
      child: Container(
        height: 50,
        color: Colors.red,
      ),
    ),
    Expanded(
      flex: 2,
      child: Container(
        height: 50,
        color: Colors.green,
      ),
    ),
    Expanded(
      flex: 1,
      child: Container(
        height: 50,
        color: Colors.blue,
      ),
    ),
  ],
)