试试这个

Scaffold(
      body: SafeArea(
        child: GestureDetector(
          onTap: () => FocusScope.of(context).unfocus(),
          child: Column(
            mainAxisSize: MainAxisSize.max,
            children: [
              Container(
                width: MediaQuery.of(context).size.width,
                height: MediaQuery.of(context).size.height * 0.3,
                decoration: BoxDecoration(),
              ),
              Expanded(
                child: DefaultTabController(
                  length: 3,
                  initialIndex: 0,
                  child: Column(
                    children: [
                      TabBar(
                        tabs: [
                          Tab(
                            text: 'Example 1',
                          ),
                          Tab(
                            text: 'Example 2',
                          ),
                          Tab(
                            text: 'Example 3',
                          ),
                        ],
                      ),
                      Expanded(
                        child: TabBarView(
                          children: [
                            Text(
                              'Tab View 1',
                            
                            ),
                            Text(
                              'Tab View 2',
                              
                            ),
                            Text(
                              'Tab View 3',
                            ),
                          ],
                        ),
                      ),
                    ],
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    );