flutter - flutter 打印特定值

Question

我有一个非常简单的问题，不知道为什么我在只需要打印特定数据值的地方找不到它
我的密码

  Future<http.Response> _trySubmit() async {
    final isValid = _formKey.currentState.validate();
    FocusScope.of(context).unfocus();

    if (isValid) {
      _formKey.currentState.save();

      print(_userEmail.trim());
      print(_userPassword.trim());

      var map = new Map<String, dynamic>();


      map['grant_type'] = 'password';
      map['username'] = _userEmail.trim();
      map['password'] = _userPassword.trim();


      http.Response res = await http.post(
        'http://sublimeapi.netcodesolution.com/token',
        headers: <String, String>{
          'Content-Type': 'application/x-www-form-urlencoded',
        },
        body: map,
      );
      var data = res.body;
      print(data);
    }
    }

它打印出这样的值(value)

I/flutter ( 5147):{"access_token":"FwYttAQIDDSRpuFFUgzznmMYgMNNfiW4OvQ4","token_type":"bearer","expires_in":86399}

我只需要打印access_token值
像这样的打印(data.access_token)

Answer 1

这里data是Map。因此，如果要从中打印出特定的值，则需要像这样提及相应的键名

print(data['access_token']);