Flutter自定义BottomNavigationBar实现图

直接看代码：

BottomNavigationBar(
            selectedFontSize: 12,
            items: <BottomNavigationBarItem>[
              BottomNavigationBarItem(
                icon: Icon(Icons.home),
                title: Text('首页'),
              ),
              new BottomNavigationBarItem(
                  title: new Text('购物车'),
                  icon: new Stack(
                      overflow: Overflow.visible,
                      children: <Widget>[
                        Icon(Icons.shopping_cart),
                        Positioned(  // draw a red marble
                          top: -6.0,
                          right: -10.0,
                          child: Container(
                            padding: EdgeInsets.all(1),
                            decoration: new BoxDecoration(
                              color: Colors.red,
                              borderRadius: BorderRadius.circular(6),
                            ),
                            constraints: BoxConstraints(
                              minWidth: 12,
                              minHeight: 12,
                            ),
                            child: new Text(
                              '101',
                              style: new TextStyle(
                                color: Colors.white,
                                fontSize: 8,
                              ),
                              textAlign: TextAlign.center,
                            ),
                          ),
                        ),
                      ]
                  ),
                  activeIcon:new Stack(
                      overflow: Overflow.visible,
                      children: <Widget>[
                      Icon(Icons.shopping_cart),
                        Positioned(  // draw a red marble
                          top: -6.0,
                          right: -10.0,
                          child: Container(
                            padding: EdgeInsets.all(1),
                            decoration: new BoxDecoration(
                              color: Colors.red,
                              borderRadius: BorderRadius.circular(6),
                            ),
                            constraints: BoxConstraints(
                              minWidth: 12,
                              minHeight: 12,
                            ),
                            child: new Text(
                              '101',
                              style: new TextStyle(
                                color: Colors.white,
                                fontSize: 8,
                              ),
                              textAlign: TextAlign.center,
                            ),
                          ),
                        ),
                      ]
                  )
              ),
              BottomNavigationBarItem(
                icon:Icon(Icons.person),
                title: Text('个人中心'),
              ),
            ],
            currentIndex: 0,
            type:BottomNavigationBarType.fixed,
            selectedItemColor: Color(0xFF1972FF),
            onTap: (index){
            },
          )

运行结果：

图片取代Icon写法：

icon: Image(
                width:20,
                height:20,
                image: AssetImage("images/bottom/person.png"),
              ),