模态框中执行switch以及其他更新状态不更新的问题

因为模态框等于是重新打开了另一个路由，所以你在AlertDialog这个widget中间更新状态不会实时更改状态

普通模态框

showDialog(
        // barrierDismissible: false, //点击外层不会关闭窗口
        context: context,
        builder: (context) => AlertDialog(
              title: Text('Caution'),
              content: Text('11111111'),
              actions: [
                new FlatButton(
                  child: new Text("Yes"),
                  onPressed: () {},
                ),
              ],
            ));

如果只是单纯的一些提示或者确认操作，这样就可以满足了，但是有时候需要在模态框上实时更新状态，比如switch或者输入框密码回显之类的，就需要这样在AlertDialog外层包一层StatefulBuilder 写法

showDialog(
      context: context,
      barrierDismissible: false,
      builder: (context) {
        return StatefulBuilder(
          builder: (context, state) {//state重新定义一个setState
            return AlertDialog(
              content: SingleChildScrollView(
                scrollDirection: Axis.vertical,
                child: Container(
                    height: val['encrypt'] == "wpa2" ? 320 : 250,
                    child: Flex(
                      direction: Axis.vertical,
                      children: [
                        Container(
                          padding: EdgeInsets.symmetric(vertical: 10),
                          child: Row(
                            mainAxisAlignment: MainAxisAlignment.spaceBetween,
                            children: [
                              Text('Remember'),
                              Container(
                                  child: Switch(
                                value: savedWifi,
                                onChanged: (bool value) {
                                  state(() { //////////setState改成state或者其他你上面定义的
                                    savedWifi = !savedWifi;
                                  });
                                },
                              ))
                            ],
                          ),
                        ),
                      ],
                    )),
              ),
              shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(15.0)),
              actions: [
                FlatButton(
                  child: new Text("Cancel"),
                  onPressed: () {
                    state(() {
                      password.clear();
                      username.clear();
                      _isObscure = false;
                    });
                    Navigator.of(context).pop();
                  },
                ),
                FlatButton(
                  child: new Text("Apply"),
                  onPressed: () {
                    Navigator.of(context).pop();
                    _joinWifi(val, 'join');
                    password.clear();
                    username.clear();
                  },
                ),
              ],
            );
          },
        );
      },
    );