Column(
  children: <Widget>[
    FirstWidget(),
    Spacer(),
    SecondWidget(),
  ]
)

Spacer创建一个可插入到[flexible]小部件的灵活空间。(像一列)

你可以试试这个:

import 'package:flutter/material.dart';

class CustomColumn extends Column {
  CustomColumn({
    Key? key,
    MainAxisAlignment mainAxisAlignment = MainAxisAlignment.start,
    MainAxisSize mainAxisSize = MainAxisSize.max,
    CrossAxisAlignment crossAxisAlignment = CrossAxisAlignment.center,
    TextDirection? textDirection,
    VerticalDirection verticalDirection = VerticalDirection.down,
    TextBaseline? textBaseline,
    List children = const [],
    EdgeInsetsGeometry? rowPadding,
  }) : super(
          children: children.map((e) => Padding(padding : rowPadding ?? EdgeInsets.only(bottom:12), child : e)).toList(),
          key: key,
          mainAxisAlignment: mainAxisAlignment,
          mainAxisSize: mainAxisSize,
          crossAxisAlignment: crossAxisAlignment,
          textDirection: textDirection,
          verticalDirection: verticalDirection,
          textBaseline: textBaseline,
        );
}

并调用

CustomColumn(children: [
                    item1,
                    item2,
                    item3,
                  ])

受https://stackoverflow.com/a/70993832/14298786的启发，在List<Widget>上使用扩展来添加sizebox:

extension on List<Widget> {
  List<Widget> insertBetweenAll(Widget widget) {
    var result = List<Widget>.empty(growable: true);
    for (int i = 0; i < length; i++) {
      result.add(this[i]);
      if (i != length - 1) {
        result.add(widget);
      }
    }
    return result;
  }
}

像这样使用:

Column(children: [
  Widget1(),
  Widget2(),
  Widget3(),
].insertBetweenAll(SizedBox(height: 20)))

这是另一个涉及for循环的选项。

Column(
  children: <Widget>[
    for (var i = 0; i < widgets.length; i++)
      Column(
        children: [
          widgets[i], // The widget you want to create or place goes here.
          SizedBox(height: 10) // Any kind of padding or other widgets you want to put.
        ])
  ],
),

Column(children: <Widget>[
   Container(margin: EdgeInsets.only(top:12, child: yourWidget)),
   Container(margin: EdgeInsets.only(top:12, child: yourWidget))
]);

与上面为了代码可读性而使用sizebox的方式相同，您可以以相同的方式使用Padding小部件，而不必使其成为Column的任何子部件的父小部件

Column(
  children: <Widget>[
    FirstWidget(),
    Padding(padding: EdgeInsets.only(top: 40.0)),
    SecondWidget(),
  ]
)