1. 关键代码

import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';

class FriendsList extends StatefulWidget {
  @override
  _FriendsListState createState() => _FriendsListState();
}
class _FriendsListState extends State<FriendsList>
    with SingleTickerProviderStateMixin {
  TabController _tabController;

  @override
  void initState() {
    super.initState();
    _tabController = TabController(initialIndex: 0, length: 2, vsync: this);
  }

  @override
  void dispose() {
    super.dispose();
    _tabController.dispose();
  }
  
  @override
  Widget build(BuildContext context) {
    return DefaultTabController(
      length: 2,
      child: Scaffold(
        appBar: AppBar(
          title: Container(
              height: ScreenUtil().setHeight(73),
              alignment: Alignment.topLeft,
              child: TabBar(
                tabs: [
                  Tab(text: '好友'),
                  Tab(text: '心动'),
                ],
                controller: _tabController,
                indicatorWeight: 2,
                indicatorPadding: EdgeInsets.only(left: 10, right: 10),
                labelPadding: EdgeInsets.symmetric(horizontal: 10),
                isScrollable: true,
                indicatorColor: Color(0xffFF7E98),
                labelColor: Color(0xffFF7E98),
                labelStyle: TextStyle(
                  fontSize: ScreenUtil().setSp(36),
                  color: Color(0xffFF7E98),
                  fontWeight: FontWeight.w500,
                ),
                unselectedLabelColor: Color(0xffAAAAAA),
                unselectedLabelStyle: TextStyle(
                    fontSize: ScreenUtil().setSp(32), color: Color(0xffAAAAAA)),
                indicatorSize: TabBarIndicatorSize.label,
              )),
          backgroundColor: Colors.white,
          elevation: 0,
        ),
        body: TabBarView(
          children: [
            Container(
              child: Center(
                child: Text("好友页面"),
              ),
            ),
            Container(
              child: Center(
                child: Text("心动页面"),
              ),
            ),
          ],
          controller: _tabController,
        ),
      ),
    );
  }
}

2. 效果图

效果图.gif